Micro CoGen.

Some of you may be following our discussion on this forum about mod'ing an ST head for 48 volt battery charging.  ( http://www.microcogen.info/index.php?topic=460.60 )   The discussion is centered on separating the 4 coils of the ST into 60 volts each, and feeding into a charge controller.

Since I'd like to retain the ST head 240/120 volt output for emergency use and keep it as versatile as possible, I am looking into other options.  I'll summarize below:

My equipment:
    ** JKson 6/1 Listeroid, propane canister muffler, no heat recovery yet.   I have a 120 volt heat rope a la Jens for heating WMO on the injector line.
    ** Powersolutions 7.5 kw ST head w/ doghouse already removed (price same as 5 kw from Joel Koch at purchase time, so I upsized)
    ** Outback 3600 watt inverters x 2, in stacked config for 240 VAC
    ** 48 Volt 5600 AH battery bank, 16 x L16 type batteries (actually currently 8 of them, because the house isn't built yet, but it will be upsized to 16 in a few months)
    ** Outback MX80 charge controller with input from 18 x 190 watt panels (3000+ watts solar total)
    ** Grundfos SQ series 240 V well pump located 320 ft deep and 800 feet from powerhouse and homesite (reason for 240 V).

With a listeroid 6/1 as the limiting factor, sizing for 2400-3000 watt charging input is appropriate.   In the current situation, when the generator is running, the system charges via the charging circuits on the Outback inverters (basically running in reverse) and the power output to the house site, powerhouse, and everywhere else is just dirty listeroid power.   We're all familiar with a listeroid's lax governor.  If I start a saw or air compressor, the frequency drops and the fluorescent tube lights flicker terribly. 

*** Here's the proposal: ***
1.  Take the 240 volt output from the ST head, transform it down to a reasonable level.  This step is skipped if you don't need 240 somewhere in your system.
2.  Rectify with appropriate sized bridge rectifier.
3.  Filter out ripple with inductive filter (choke) and large capacitor
4.  Feed into the solar charge controller.

Many people on this forum already have a solar charge controller, and the limiting factor in this case is the rated open circuit voltage (Voc) of your charge controller.   If you can breaker and keep the inputs from the generator (120 V rectified DC) and DC in from the solar arrays separate (diode protected from backfeed), you can use the same charge controller.   When it's dark, charge using generator.  When the sun is shining, charge via solar.   It could even have an automatic transfer switch, but not necessary considering the manual start of the 'roid anyway and diode protection.   And there could still be regular 120 V AC plugs next to the 'roid for emergency use.   I like....  :)

BruceM and Mobile_bob have given great ideas.
Toroidal transformers would be the most efficient at >90%.
Here's BruceM's schematic for 120 V DC into MX80 charge controller with overvoltage protection:

http://www.microcogen.info/index.php?action=dlattach;topic=460.0;attach=1032

Midnite Solar is going to come out with a new "Classic" charge controller that can handle high voltage input, but it will cost ~$700.   The transformers above are more cost effective.  The Morningstar Tristar-60 is a good price, $200, and can handle up to 150 V DC input and 60 Amps output @ 48 volts.

>  ** Outback 3600 watt inverters x 2, in stacked config for 240 VAC

Dang.  If you didn't have those on hand, the Xantrex XW6048 could take your genset 240V and charge with that.

Oh, the Outback inverters do take the 240 genset voltage, one hot lead to each inverter, and charge with it.   But you still get the 'roid power to everything when charging instead of clean inverter power.   Therein lies the problem.    Don't get me wrong:  I have 200 hours on the 'roid so far and I'm very happy with it, except no electric start (my wife can't start it).    But it would be nice to eliminate the 'roid's fluctuating AC power except for unusual use and have it supply constant amps for charging instead.

Thanks for starting the new thread Marcus, and you did a great job on the summary.

Pity your existing AC charge capability insists on routing AC through.  I'd contact Outback and see if there is a possible mod to change this.  An AVR and governor fix might also be in order. The AVR solves most of the problem, it will keep voltage up even though frequency varies.

Re: starters-  I wonder if there are enough guys interested that Dave (XYZ'er) might consider making a batch of 12V friction starter kits?  His design looks like winner, and except for outside sets (rain, frost) friction starters are simple and reliable.  

One error in your summary, which was mine, caught by Mike: The PWM Tristar-60 by Morningstar is the $200 unit, it can only handle 125VDC max voltage input.  Their MPPT units are also called Tristar-60, but these are over $500.  They can handle 150VDC input.  

The Outback MX-60 and MX-80 are rated for 145VDC max input, for operational use.

There will be more toroidal transformers up on ebay, we can find something else for your filter choke, but I'd snatch the other two right away if you're going this route.    If we find something else suitable for the step down transformer, then we can use them for chokes, still, that gives us some flexibility.  

i agree with Bruce, you better grab those toroids while you can,
to buy new ones is pretty cost prohibitive in my opinion, last ones i checked on
were priced as if they were made of unobtanium by tesla himself and stolen from a museum somewhere.

ok, maybe not that bad, but pretty high cost for good ones

bob g

OK, I bought all 3 of the 1200 watt $50 ones.   Having a duplicate for a spare seems prudent.   Let me know if you recommend another purchase!   thanks

Marcus

Ok, Marcus.  Good call on the spare, I'd have done the same.

You can order toroidal transformers from several US suppliers, custom to your spec or from standard designs, but they are a bit pricey.  Antec is a good supplier for smaller ones, his test specifications have always been accurate.  He sells on ebay.  I have at times just bought bargains for the cores, which I then rewind the stripped cores by hand for chokes, or rewind secondaries to get what I need as a transformer.

Ebay item 360217315683  (x 3), with all six of the dual secondaries in parallel, would do the job for the filter choke. This one is $39 plus $10 shipping.  Good deal for a 1000 watt core.

Quotethe Outback inverters do take the 240 genset voltage, one hot lead to each inverter, and charge with it.   But you still get the 'roid power to everything when charging instead of clean inverter power.

That's the problem I have with the Xantrex SW+5548's, not only do they pass the power through, they don't charge evenly so sometimes one inverter will draw 20A from one side and none from the other which even with the SR2 causes voltage issues and flickering.

Jedon, that sounds a lot like a hookup (neutral)  problem between the two units, rather than a Xantrex design problem.  I'd  check the hookup compared to the manufacturer's diagram for this configuration very carefully.

I studied the hookup instructions for quite a while and think I have it set up right, it doesn't always draw unevenly, only after it finishes the first bulk charging state, so when I first turn it on the SR2 gives 25A evenly to each inverter, then when the inverters don't need the whole 50A anymore the primary inverter takes over the charging. The hookup is pretty simple, the inverters are grounded, the neutrals are bridged and one hot to each inverter.

one inverter charger after the first bulk charge is slow to sample the battery voltage,
this allows the faster to pick up the voltage because it is charging, and the second being slower
to sample see's the batteries at the higher voltage and thinks they are charged, so it drops back to
float.

thats my theory  :)

there maybe a setup to where you can program a specific timed bulk, timed absorption and then drop to float
instead of allowing the units to sample and decide for themselves what the batteries needs are.

having never studied the inverter/charger theory of operation, because i don't plan on incorporating this type
of dual purpose component, i can only imagine this is the problem, and it is likely there are ways to correct for this
issue.

you might want to double check the manuals and see if they need to be programmed differently when connected in tandem
than they are programmed for singular use.

there might also be a programmable delay from sample to begin charging, if so you might want to extend the time to mid range
so that both units have time to sample and then wait to initiate startup. that way it wouldn't make any difference which could sample
faster, because it would have to wait several seconds to initiate startup, giving the other added time to catch up.

i might be wrong, but i bet there is something along these lines that is at the bottom of the problem
bob g

One thing I have noticed is I'm pretty sure one of the units has a busted battery temp sensor, perhaps then one is sensing the battery voltage "actual" ( higher voltage right now since it's cold ) and one is sensing compensated voltage ( lower right now ).

Link to diagram on how to hook two up:
http://www.xantrex.com/web/id/1075/docserve.aspx

Even if this is solved it will still flicker with the listeroid of course.

I think you've solved your own problem, Jedon.  One unit thinks the battery is done first because of the broken temperature probe.

I looked at the diagram, and it does look like there's no way to have an AC battery charging source without it also feeding the AC.  That screws the  Xantrex inverter/charger combo benefits for non-3600 rpm gensets.  Their designers must not leave the lab much.     

It's actually heartening to hear someone else have the same problem, jedon.   My setup is wired similar to yours.   Here is Outback's wiring diagram which is precisely how my setup is wired:
http://www.outbackpower.com/pdf/wiring_diagrams/4-7-2kw-120-240vac.pdf

And mine also has problems charging to completion:  this afternoon, when I got to my land, the TriMetric read 80% battery charge.   Combo raining & snowing.  Turned on the 6/1, started charging through the Outback inverters and ran a halogen shop light to have some lumens while making a counter.   Must have been pulling 3000+ watts:  2000 W charging and 1200 W halogen light.   Frequency initially dropping to 53 Hz.   When we left this evening after running about 3 hours, I check the TriMetric again and it read 85% charged, no current going to the batteries, and voltage of 52+ V.   (Should have higher charged voltage.)

Marcus

That's gotta be pretty annoying when you have paid for "first class" gear like Outback or Xantrex, and then find that very basic operational stuff (like charging and operating with non-3600 rpm generators) doesn't work right! 

I just assumed you could just unbox and hook up these higher end systems and all would work well.  Apparently, NOT.

Marcus's "backdoor AC-DC charge via solar charge controller" fix is going to be popular, I think; it fixes the non-3600 rpm generator problem, and also the crappy charger issue.

I guess it makes me feel a little bit better about not being able to tolerate being around the commercial gear (EMI and my shot to hell brain) but it sure is a PITA to have to design and build everything from scratch.

QuotePity your existing AC charge capability insists on routing AC through.  I'd contact Outback and see if there is a possible mod to change this.  An AVR and governor fix might also be in order. The AVR solves most of the problem, it will keep voltage up even though frequency varies.

So, I've looked carefully through the Outback wiring diagrams, and technical documents on their website.   There doesn't seem to be any mod.   Seems reasonable, though, if an inverter is just a transformer, rectifier, and a bunch of fancy proprietary electronics:  you can't put electricity through a transformer in both directions at once.  When it's charging, there's no possible way to get clean power through the inverter, unless they put another transformer or set of transformers in the box.

QuoteRe: starters-  I wonder if there are enough guys interested that Dave (XYZ'er) might consider making a batch of 12V friction starter kits?  His design looks like winner, and except for outside sets (rain, frost) friction starters are simple and reliable. 

I like his friction starter mod.  and I'd be interested.   I've also thought of another starter mod --> has anyone bolted a ring gear onto the ST or alternator pully and then mounted a starter to that?

Marcus

Yes, Marcus, I do think I've seen generator mounted starters on the LEF forum.  That makes for a more manageable sized starter ring.

Member Jens did gen head mounted "Flex plate" (because they were designed to be a flexible coupler!) ring gear starter set up.
Ask him.
JTodd on the LEF also had an earlier type remotly mounted belt drive ringgear/diesel starter set up. He changes to direct drive due to the niose of the faster spinning ring gear on the indirect.
Ask them.

Regards
SteveU.

shipchief who is also a member here, was the first to remote mount a chevy flex plate to the st head
to make a starter for his 25/2

i have seen it operated and it works well, even on a rather large application like the big twin, it should spin
the ass off of a 6/1

bob g

Quoteyou can't put electricity through a transformer in both directions at once.  When it's charging, there's no possible way to get clean power through the inverter, unless they put another transformer or set of transformers in the box.

The Xantrex manual states that in the case where more watts are needed than the generator alone can provide, that it can supplement it from the batteries.

Jedon, That might mean the Xantrex could be modified... I'd write to Xantrex, tell them your model number and what you'd like to do.  Who knows, they might actually have tech support.  ::)

I'll give it a shot, not expecting much though since they can't even keep spam out of their forum and it took them a month to reply to my request for a generator start module that I was just SOL.

QuoteThe Xantrex manual states that in the case where more watts are needed than the generator alone can provide, that it can supplement it from the batteries.

Jedon,  I think they are taking the generator power and sync'ing the inverter to it, then combining power from the generator and batteries.   Still power is only going one direction through the inverter at a time.  With a listeroid, this would cause lots of trouble, with RPM's going up and down.   I just envision a disconnect by the inverter because the 'roid can't keep up, causing an overload situation on the 'roid, tripping breakers.   On the positive side, when running on generator power you aren't limited to the ~3000 watts output of a 6/1.

Thank you all.  Very encouraging about the ring-gear on an ST head.   Deserves a bit more research.   Hey, SteveU. good to hear from you!

The inverter is a bit fancier than that, you can set max passthough amps so just set it low enough not to cause the listeroid to stall. The inverter does kick stop taking power from the listeroid whenever any part of the power falls out of spec but it happens in ms so it's not noticeable. Hey maybe I can set the passthrough amps to 0?! Why didn't I think of that before. I'll give that a try today.

I figured I'd continue my "Smoothing Capacitor" thread here since Marcus and I are attempting to do the same thing in a somewhat different way. Any objections?

At this point I'm not smoothing the dc and as long as the Flexmax stays happy that's what I'll continue to do.

The stud mount diodes came in the other day and I mounted them to the heat sink and hooked everything up. It's been running about 6 hours today and everything's working well. The Outback puts out between 27 and 32 amps and is set at 31. The Listeroid is putting out 2000-2300 watts and there are some loads in the engine room which are not on the Outback. I'm not getting any significant heat from the UPS, batteries, rectifier heat sink, transformer or the Outback. The Outback fan does kick on for less than a minute every 5-10 minutes but is only warm to the touch. My basement where everything is located is about 50°F.

I did a load of laundry to increase the engine load above what the Listeroid would normally see. During this test the water pressure booster pump and the sump pump came on intermittently. The engine load remained constant and the needed amps were pulled off the battery bank. After the test was over the batteries came back up to voltage quickly but never went below 50vdc.

Even with this inefficient UPS and under normal winter house loads I still need to keep a 600watt space heater running in the back room to keep a good load on the engine. That's nice to see.

One funny thing. I was out in the gen shed and noticed a very low load on the engine (600 watts) by the time I got back to the basement the Outback was charging normally. The manual says it recalibrates VOC from time to time and maybe that was it.

If anyone buys stud mount diodes try to find ones with long studs. I couldn't double nut mine and I didn't even have enough room for a washer.

Listeroid/ST5/120vac---->120 to 70vac transformer---->Bridge rectifier feeds 98vdc to---->Outback Flexmax60---->48v Battery bank---->Inverter---->120vac to main panel.

Thanks, Geno

Hey Geno,  good to have some more input.   I've been following your smoothing capacitor thread, too.   Welcome over here.   Looks like you don't have any electrical inspections coming up -- nothing in conduit (!), but easier for us to see what you did.   So you're not smoothing the rectified DC at all now?

I will certainly be cleaning up and addressing the safety issues once I'm sure everything is good to go. I do understand the power in those dc lines.

No smoothing at all, straight from the rectifier into the Outback. So far so good. I've been monitoring everything very closely all day. It's nice to be able to run an extra 1000+ watts for a little while without turning anything else off. I can't overload the engine either. It cost me a good bit but I saved a lot doing it myself and finding the right deal.

Thanks, Geno

Thats great Geno! Nice full load testing. 

Keep an eye on the Flexmax "no load" times;  it's possible the Flexmax is getting confused by your "lumpy" DC, if it's doing it too frequently.  If not too frequent, hooray, you saved some bucks on  filtering.

Reminder to others trying this-  Geno did some very smart, careful testing (short runs) at low charge rates to make sure the Flexmax was functioning OK (operating normally and no excessive heating) with unfiltered (just rectified) DC.

The whole project is an impressive piece of first class DIY systems engineering with largely surplus gear.

Congratulations, Geno.

Geno:

you get a solid 10 for persistence and a working solution to the problem, hats off to you for that.

now we need to take the next step and see how we increase the efficiency?
which may or may not be important to you or others?

good work

:)

bob g

Yes, very impressive Geno.   I wouldn't have had the cahones to pump that unfiltered power into the Flexmax.

Quoteit's possible the Flexmax is getting confused by your "lumpy" DC, if it's doing it too frequently.

Keep us updated, because if this works I may not have to put in a choke and capacitor.

Thanks for the kind words gentlemen. As you probably know this stuff is what's fun to me. The usual, mindless distractions which keep so many people fat, dumb and happy don't exist in my life. I know it makes me different and I couldn't care less. The road less traveled is far more interesting.

During my earlier, low power testing I *think* I saw "finding new VOC" or something similar on the screen with 0 amps going to the batteries. I should have it running all day today and will keep an eye on it. My engine occasionally burps on what I assume is a vapor bubble reducing output for a few seconds. It's quite rare in the winter though.

Flexmax Manual:
"Re-Cal" There are certain abnormal conditions that can confuse the current measuring method in the Charge Controller. When and if one happens, the Charge Controller will temporarily stop and re-calibrate. This may happen because of negative current, i.e., current flowing from the battery, or a tripped PV breaker. A new VOC is also acquired during a Re-Cal."

At this point increasing efficiency means a new 48v inverter. It's gonna be a while before I take that step. I'd probably want another 8 batteries first and I'd want them sooner rather than later.

Outback measures temps using 1-255. 1=210C and 255= -68C. Very confusing. The only chart I could find on their website was a graphics file. This file was for their battery temp sensor and I'm assuming it's valid for internal Flexmax temps as well(edit, incorrect). With some OCR and a little Excel work I came up with this file. It's free to download, modify and distribute to anyone.
Outback Temperature Chart (http://genedevera.com/temp/rts.xls)

Thanks, Geno

you can go into the menu of the FM 60 and set the input voltage unsure of what it is called it was UPick on the MX60. this works really well if you have a steady input like the lister unlike PV panels that change voltage all day the lister doesn't so no need to let the outback work to find the MPPT voltage just watch it for a while and program it for what it has picked. A side note Midnite solar will be releasing the Classic charge controller and it has a lot higher operational voltage so you could take out the step down transformer. This is what I plan on doing.

"you can go into the menu of the FM 60 and set the input voltage unsure of what it is called it was UPick on the MX60. this works really well if you have a steady input like the lister unlike PV panels that change voltage all day the lister doesn't so no need to let the outback work to find the MPPT voltage just watch it for a while and program it for what it has picked."

That's a great tip, Halfcrazy! 

I saw the U-Pick options for hydro and fuel cell apps. and realized they may help. Things are up and running now. I looked through the menus and manual and haven't yet found how to display the MPPT voltage or % of VOC. I can see what's coming in and going out. In U-Pick I can set the units MPP to a fixed % of VOC.
A little later........
I set the unit to U-Pick and adjusted the MPP % to the highest wattage output. That was around 55-60% of VOC which is close to ½  When switching between these modes the unit does a restart and output goes to 0 for around 10 seconds.

In this pic if min is set to ½ MPP is not tracked below 50%VOC. If set to full MPP is tracked close to battery voltage. I wonder if MPP goes below 50% VOC when set to ½ the unit does a restart. This could be the cause of my anomaly. For the moment I'm setting it to full and leaving it in auto track mode.

(http://genedevera.com/temp/range-limit.jpg)

Thanks, Geno

Manual:
The Charge Controller searches for the MPP voltage by tracking the input voltage up to one half  (default) of the Voc, which is based on values appropriate for a solar array. Micro-hydro and fuel cell systems can require a broader range, normally on the lower end. Adjusting the lower limit, expressed as 1/2 on the display screen, for FULL allows the Charge Controller to track the input voltage close to the battery voltage instead of 1/2 (or 50%) of the Voc.
This adjustment only affects the initial tracking at the beginning of the day and any subsequent trackings
caused by Auto-Restart or any forced restart of the Charge Controller.

U-Pick % (Voc) MPPT mode operates the PV voltage at a user-selected percentage of the VOC which is displayed in the Park Mpp % Voc screen. Press the <NEXT> soft key to view the Mpp Range Limit % screen. The Mpp Range Limit % Voc adjusts the upper Mpp limit of the VOC. The default Charge Controller MPP voltage limit is set at 90% of the VOC and is normally left alone for an array. Setting min to 1/2 reduces the initial tracking time on a high input voltage array and also tracks one-half the VOC voltage.
The MPP adjustable Charge Controller limits are 80%, 85%, 90%, and 99% of the VOC. The min range limit setting may be set to FULL if something other than a PV array is connected to the input of the Charge Controller, such as a micro-hydro generator (see page 58), but the VOC cannot exceed 150 VDC at any time. Press the <min> or <max> soft key to adjust the MPP range limit.

Auto Track MPPT Mode (the default and preferred mode) automatically tracks the PV upon wakeup and then tracks the MPP of the array. If the Auto Restart is set to 1 or 2, the Charge Controller awakes every 1.5 hours and does an initial tracking. U-Pick % (Voc) MPPT mode operates the PV voltage at a user-selected percentage of the Voc. This percentage is displayed in the Park Mpp % Voc screen along with the current output wattage. The wattage value changes as the user adjusts the Voc percentage, allowing the user to lock-in the most advantageous percentage value. U-Pick % acquires a new VOC value every 1.5 hours if Auto Restart is set to 1 or 2.

Geno, I think it might be worth trying the "full" range setting, as mentioned in the manual for wind or non-PV sources.

It's hell reading other engineer's explanations (manual), I can only imagine how hard it must be to sort out my drivel.

Are you going to be feeding PV into the Flexmax, too?

Best Wishes,
Bruce

I have to read portions of the manual more than once to get a grasp of what's going on.

I put it on full yesterday morning and didn't notice any events where output went to 0. I ran the engine about 9 hours also. On 2 occasions the display went to garbage characters but I'm pretty sure it was still functioning. A power cycle fixed it. I'll clean and reseat the connections this week. There are several issues like that reported in the Outbackpower.com forum.

There wont be any PV here for the foreseeable future. $ is one reason, the NE isn't the best place for it and my many trees provide a lot of shade for the house in the summer.

Thanks, Geno

Now that you mention it, Geno, I don't recall a lot of long sunny winter days in Watertown, NY either! (My home town.)

But I can't think of a more beautiful place to live than where you are.

I spent 4 years at SUNY Oswego.  I made parole with my BS in technology education in '91.  I couldn't get away from the overcast windy days on lake Ontario fast enough.

My family had an 1828 vintage stone farmhouse up on the Tug Hill Plateau outside Watertown, overlooking Lake Ontario and Toronto.  Much of the winter we had 50mph winds at night, coming off the lake.  The house's name was Windswept for a good reason.  About 2 weeks in January with below -27F temps (the magic number for school closing).  The stone part of the house had no insulation in the double stone walls,  with a hollow cavity between large enough allow convection chilling of the inside wall. Heating was $600 in oil and $600 in electric per month (in the early 1970's!).

This might be part of why I moved by myself to Arizona at 18 and stayed.

I'm a good bit east of there near Lk. George and pretty close to the Vt. border. I've been to the Tug Hill plateau several times. Pretty country. Bruce, you lived on the plateau through the winter???? The lake effect snow there is mind boggling. In early winter you hear reports of 2-3' in a single day. If you live there in winter you need a bulldozer, not a plow truck.


http://www.tughill.org/region.html
According to data from Northeast Regional Climate Center Department of Earth & Atmospheric Sciences at Cornell University the highest recorded monthly snowfall for the Boonville area was 156.4 inches in January of 1978. The highest recorded yearly snowfall for that area was 346.1 inches in 1976-1977. The highest recorded monthly snowfall for the Montague area was 182 inches in January of 1978, the highest recorded yearly snowfall for Montague was 466.9 inches in the winter of 1976-1977.

Thanks, Geno

Wow, that's a beautiful piece of land, Geno, and lots of it!  When I was a kid our family skied at Paleface Mtn. and Whiteface Mtn. almost every winter.  How far are you from Whiteface?  The upper mountain at Whiteface has some uber-vertical, uber-icy runs!  (Olympics held there once.)

After we got about 4 foot of snow on the ground, covering the barb wire farm fences,  you could go anywhere via snowmobile.  There were farm fields, a pond and 500 acres of woodlot with creek behind us, and I could snowmobile about 4 miles to the top of the local ski area.  First run was free!  Dairy farming and beef raising, many of my rural central high school mates were hard working farm kids.  

They have an amazing fleet of monster snow plows around Watertown, for obvious reasons.  The problem for us on the Tug Hill Plateau was drifts from the winds at night.  Often with banks over 8 foot tall on both sides of the road, it would fill in 5-6 foot deep overnight.  We learned to "toboggan"; with a VW bug (light in front and no radiator/fan/belts in front to ruin) you could get a running start and toboggan across a drift that covered 30 foot of road.  You had to compensate for slope before you hit the drift- no steering till you hit the road again.

Lots of fun for youngsters, if it was -28F in the morning and school was closed, we'd cheer and put on our leather face masks and go snowmobiling.  There was a flat "shelf" cut into the top of the snowbanks along the roads, from the upper wing of the snowplow.  You could really fly up there, about 8 foot or so above the road,  but you had to watch for driveways!  Wind chill hadn't been invented yet, or we would have died of frostbite.   ;)

I'm about 1.5 hrs from Whiteface or Killington but I haven't skied in years. My property is only about 10 miles from Gore Mt. Yes, the top of Iceface (local lingo) requires sharp edges and a stout heart. The VW toboggan sounds like fun. Never heard of it before but it makes sense. I believe they have a flat belly so there would be little drag.

I partially took apart the Flexmax last night but I wasn't comfortable going any further without some docs. I was able to get a tweaker in there and reseat the display cable without completely taking it off. I also reseated the board on the other end of the cable. We'll see what happens next time I put it in service. Outback has a doc explaining how to change the fan which should explain how to further disassemble the unit.

Thanks, Geno

That is a nice area you live. I skied all three Mt's. your right about Iceface. :o I fell once and continued bouncing and sliding that seemed for ever. You better have razor sharp edges when tackeling certain trails.

That whole area was my get away from the stress of life. Great boating ,camping and hiking.

I miss it.

Henry

What a great location, Geno.  A small sailboat and a kayak and you're all set...oh yeah, you need a cabin!

Good luck with the Flexmax, I hope it was just the display cable/connectors.

My Flexmax display went to garbage last night sometime after I pushed it to 33 amps. I checked the battery voltage before I shut it down and it was good so I know the unit was still charging. I'd say it's time to look into some smoothing. Ya can't say I didn't try and the smoke is still where it's supposed to be.

Thanks, Geno

It sounds like an  EMI problem-  and diode noise might be a big part of it.  Diode noise will get worse as current increases.  I'd try putting 0.1 uF metal film cap around each diode on the bridge. Pick the cap max voltage rating of at least double the transformer AC output voltage.  (1.4 times AC for peak DC plus some head-room.)

Is the negative leg of the DC supply connected to your system ground?  That might also be helpful.
(But check the documentation carefully first- this may already be done in the charge controller).

A valiant effort, Geno!   Well, my toroidal transformers should be here soon.   Then I can discuss w/ BruceM some more on buying the next components in my filtering setup....

Quote from: BruceM on January 19, 2010, 10:16:01 AM
It sounds like an  EMI problem-  and diode noise might be a big part of it.  Diode noise will get worse as current increases.  I'd try putting 0.1 uF metal film cap around each diode on the bridge. Pick the cap max voltage rating of at least double the transformer AC output voltage.  (1.4 times AC for peak DC plus some head-room.)

Is the negative leg of the DC supply connected to your system ground?  That might also be helpful.
(But check the documentation carefully first- this may already be done in the charge controller).

Radio Shack has the caps for $1.49. I assume you mean they need to be hooked up from the top to the bottom of each diode?

I'll check ground on the Flexmax tonight. I did ground the case.

My losses with this setup are very bad. My UPS says its putting out 12 amps and my Killawatt in the engine room says 20. Yikes.

Thanks, Geno

20 amps input and 12 amps output, hmmm 60%?

my earlier guess wasn't far off, but

it does work, and now you can work to see what can be done to improve the efficiency

gotta start somewhere!

:)

good job, thanks for the update

bob g

Just make sure the caps are metal film types, Geno.
Yes, one cap leg goes to each end of each diode in the bridge.

Thanks for starting such a great thread Marcus and to everyone else for their insights. I'm new to posting on the forum but I've been lurking for a while.

I was happy to trip over it because I'm going to be in a very similar position. I haven't purchased any of the kit yet but I'm strongly leaning towards Outback. However, it is clear from the Outback forum that the FX inverter series charger has poor power factor (especially under light loads) and this causes people all sorts of grief getting things to work with a generator. This seems to range from not working at all through to low charge rates and poor AC delivered via the transfer switch in charge mode.

For these and other reasons I had pretty much decided to feed the house from inverter output full time and charge the batteries directly. I was also planning to use an Outback charge controller to do this. I don't have a solar array yet but I might add one.

My initial though was to transform and rectify output from my gen. set (Changfa 195/ST7) and feed the output into the charge controller. I was expecting to have to do some filtering but really not sure how much I would need. I did query Outback on this approach and they seemed initially supportive but a subsequent question about acceptable AC ripple on the charge controller input met with silence.

I see that Geno has tried this approach (without the filtering) with some success which is great. However, it looks like the efficiency was not so good. I don't know what sort of power factor this setup is presenting to the head but it might be a consideration. I'm really not sure how well ST heads handle poor power factors ...

I'm currently exploring an alternative that I thought I'd throw out for comment. Folk on the Outback forum  pointed me at this: http://www.weirdstuff.com/cgi-bin/item/22081# Pretty cheap for a 3kw switch mode power supply. Better still it is power factor corrected and should present a nice regulated DC input to the charge controller without further filtering. Efficiency is listed at 90% for 230V in. Not bad. It might be possible to beat this with a good toroidal transformer/rectifier/filter setup but I'm guessing it would be close. And I doubt you could beat the price unless you had the parts just sitting around  :)

Looks interesting but I can't open the specifications.  Oddly listed as a rectifier module instead of DC supply, also.

Could be a simple, cheap way to get your DC for charging!

weirdstuff.com/cgi-bin/item/22081# was a hot swap rectifer pack.   Not sure what the specs were.

I've heard the outback gear is very "twitchy" about the power quality, it's expecting Grid.

iota chargers are reported to work down to DC, so maybe throttling back till the output sags, is a way to find the slow speed.   As the battery charges up, it will pull less amps.

Quote from: BruceM on February 09, 2010, 11:46:24 AM
Looks interesting but I can't open the specifications.  Oddly listed as a rectifier module instead of DC supply, also.

Could be a simple, cheap way to get your DC for charging!

I found the specs here: http://cherokeepwr.com/ds/CAR3000.pdf

The ad. quotes the model as CAR3010L1NH which seems to fit.

Simon.

and this:  http://www.datasheetarchive.com/datasheet-pdf/022/DSA00383318.html

Awesome find, but its output is 48V DC which is only nominal battery bank voltage.   Not high enough charging.  :)   Correct me if I'm wrong.   I got all excited....

QuoteI see that Geno has tried this approach (without the filtering) with some success which is great. However, it looks like the efficiency was not so good.

If you're talking about the efficiency of 60% quoted a few posts back, he's referring to the efficiency of the UPS he's using instead of an inverter, not the separate charging circuit.

Marcus

Quote from: mike90045 on February 09, 2010, 12:06:07 PM
weirdstuff.com/cgi-bin/item/22081# was a hot swap rectifer pack.   Not sure what the specs were.

I've heard the outback gear is very "twitchy" about the power quality, it's expecting Grid.

iota chargers are reported to work down to DC, so maybe throttling back till the output sags, is a way to find the slow speed.   As the battery charges up, it will pull less amps.

The grid-tie Outback inverters are indeed quite picky about the AC input and Outback does not recommend them for off-grid/generator use.

The off grid FX/VFX series have specs more appropriate to generator input. However, I know people have trouble with the charger as it is not properly power factor corrected. Probably plays hell with those big box store 3-5kw sets. I'm hoping the ST will be able to keep it in line should I ever need it.

Interesting to hear about the IOTAs. I have the impression that most switch mode power supplies will work down to DC (someone please correct me if I'm wrong) and as far as I can tell the IOTAs are just a SMPS with battery charging smarts.

I am quite keen to spin my Changfa down to maybe 1400 rpm or lower when battery charging. Much quieter and I don't need full power. 3kw would be plenty. But thats pushing the AC input frequency limit on this 'weirdstuff' power supply (listed as 47-63Hz). If I can hold the voltage up (probably using some sort of AVR) does anyone know what might happen if I supply the unit with 47-40Hz AC?

Simon.

Quote from: mbryner on February 09, 2010, 12:23:15 PM
Awesome find, but its output is 48V DC which is only nominal battery bank voltage.   Not high enough charging.  :)   Correct me if I'm wrong.   I got all excited....

The output can be adjusted up to 52.8V. I'm planning a 24V battery bank so it won't matter for me. Maybe 52.8V is enough to charge (and more importantly I suspect) equalize a 48V bank through the charge controller ...

that is not high enough, it takes 57.6 volts dc for a flooded lead acid battery to be fully charge at room temp
and a bit over 60vdc to do an equalization of a 48 volt bank of flooded lead acid batteries.

most charge controllers such as the mppt units have buck converters, but i am not aware of any that use boost converters
or a combination of both, so they are not a good way of boosting the voltage in my opinion.

bob g

Has anyone looked at the Newmar stuff.

Lloyd

http://www.newmartelecom.com/Power-Modules/Power-Module.html (http://www.newmartelecom.com/Power-Modules/Power-Module.html)
These Versatile Rectifier Modules function as either power supplies or battery chargers for 12, 24 or 48 volt systems; positive, negative or floating ground. They may be employed singly or in combination, enabling the installer to scale the system anywhere from 500 to 10,000 watts per rack. Units may be paralleled for N + 1 redundancy and alarm contacts allow local or remote monitoring. An optional DC quick connect wiring kit allows easy replacement of modules without system shutdown.

Power Modules may be used separately as a power source, or they may be integrated with the Power Function Manager to greatly expand the system capability with other functions such as digital output monitoring, powering multiple loads via circuit breaker distribution and low voltage battery disconnect.

Could these $99 48v power supplies be directly hooked up to a 48v grid tie inverter such as an outback, xantrex etc.?

When I read some specs on MPPT solar charge controllers, I believe I read something about boosting panel voltage on cloudy days...if they have a boost converter, then you might be in luck for 48V.

Bruce:

you may be right, i don't know for sure because i haven't followed the technology for a couple years

generally speaking though an mppt is best used with a higher voltage panel set and in buck mode,
when the cloud cover is such that the voltage drops to below the charge level there generally is not much power
available to cover the losses of conversion of a boost converter.

but they may not always be the case?

bob g

There is a switching DC_DC design which can do both buck and boost, and I think that's what the newer MPPT units are doing.  There is no penalty for boosting vs bucking with that topology.  I just can't remember which unit did the boost conversion...

It doesn't look like the Flexmax or MX series does any boosting.

From the Flexmax manual

Nominal Battery Voltage Nominal Array Voltage (recommended)
12V 24V (or higher)*
24V 36V (or higher)*
36V 48V (or higher)*
48V 60 V (or higher)*
60V 60V (low temp is less than 5°F) or
72V (low temp is greater than 5°

* When sizing an array to charge controller with a distance of 70 feet or greater, OutBack recommends the nominal array voltage be slightly higher than the recommended nominal array voltage. Example: A 36VDC nominal array recharging a 12V nominal battery with an array to charge controller distance of about 70 feet or greater. Sizing the nominal array voltage higher than the nominal battery voltage ensures that the Maximum Power Point is always above the battery voltage. The Maximum Power Point will  decrease as the panels warm up, thus lowering the output of the array. The Charge Controller Charge Controller will not be able to boost the output if the Maximum Power Point of the array is at or lower than the battery voltage.

The MX60 is a buck type converter and cannot boost the output current when the PV array peak power point voltage is at or below the battery voltage as may happen on hot days in 24 VDC PV and a 24 VDC battery system or a 48 VDC PV and a 48 VDC battery system.

FLEXmax 80
The Charge Controller is a buck type converter with the following properties:
•80 amp DC output current limit (default setting)
•Listed to operate continuously at 80 amps (40°C/104° F)
With an 80 amp Charge Controller output current limit and PV array output higher than 80 amps offers little, if any, current boosting or Maximum Power Point Tracking advantage; in effect, any excess power beyond 80 amps is lost.


Thanks, Geno

Just to ask again (cos it probably got lost in my original post). Does anyone have any idea how a switch mode power supply like this will behave if I feed it 40Hz AC? I'm hoping to spin my head and engine at lower rpm while charging batteries ...

Sounds like the IOTAs might go down to DC but the specs show the same AC range (47-63 Hz)?

Simon.

Thank you,  Geno.  Looks like it's buck or nothing.  My memory/imagination is wrong again.
Dandy for a 24V system, I guess.

Yellowhead-  I wouldn't go below 50Hz myself unless someone gave me some free Iotas to experiment with/smoke for fun.  Many switchers will do 120V 50/60Hz or 150-180 VDC input, but much below 50Hz the input storage caps aren't going to be big enough in most designs.

Quote from: BruceM on February 09, 2010, 09:06:13 PM
Thank you,  Geno.  Looks like it's buck or nothing.  My memory/imagination is wrong again.
Dandy for a 24V system, I guess.

I thought I'd seen a charge controller that did buck/boost as well. I think this was it (although its still not available):

The MidNite Solar Classic MPPT controller is destined to be the type of product that will truly change our industry. With a very aggressive list of features, the Classic from MidNite Solar is once again raising the bar in performance. The Classic has three separate modes (recipes) to choose from: Solar, Wind & Hydro. Each mode has key settings making setup a snap. Custom changes are also easy with the easy to navigate menu structure. The Classic also widens the battery bank size by allowing 12, 24, 26, 48, 60 & 72 Volt Nominal Battery Bank sizes. With maximum output at 60A, the controller keeps cool with an oversized variable speed ball-bearing fan. The design of the cooling fins on the chassis prevents the fan from running most of time, but the fan is easy to change if the controller lives in extremely harsh environments.

An industry first: Boost Mode. All other MPPT controllers on the market have Buck Mode, meaning they down-convert the higher array voltage to match the lower battery voltage. The Classic has Boost Mode allowing it to charge a 48Vdc Battery Bank from only a 24 volt source, for example. The Classic can Boost up to 60A of input voltage converting it to charge a higher voltage battery bank. Another first is the ability to parallel the inputs and outputs of multiple controllers allowing them to act as one larger controller. The Express-Bus communication network allows the Classic to synchronize with each and the MidNite Solar Equinox Communication Controller.

Quote from: BruceM on February 09, 2010, 09:06:13 PM

Yellowhead-  I wouldn't go below 50Hz myself unless someone gave me some free Iotas to experiment with/smoke for fun.  Many switchers will do 120V 50/60Hz or 150-180 VDC input, but much below 50Hz the input storage caps aren't going to be big enough in most designs.

Thanks for the warning Bruce. I wouldn't try it on an IOTA  :) I might push the limit on one of those $99 power supplies though to see what happens. I need to go and review SMPS theory a bit to understand why the input caps are the limiting factor. 47Hz would be 1400rpm on my set (more or less) which might work out just fine ...

Yellowhead,  Thanks for posting the Midnight Solar info; I guess that's where I saw the boost converting MPPT mentioned.

One possible snag on Midnight's future product is that the combined buck/boost converter designs I've seen aren't quite as efficient as a straight buck (down) converter, which is the highest efficiency (and simplest) topology for DC-DC converters.

I don't think you'd have trouble at 47Hz. 

If a schematic was available, the output voltage of the cheap 48V switcher might be raised. 

Hey guys I am a Beta tester for Midnite solar's Classic I have 3 running here. I can assure you they are as efficient as anything else out there while operating in buck mode. They have some great features and more to come the first great feature is the ability to just upload software to them vie usb or ethernet. They assure me they sill be as efficient in boost mode but we have yet to get that far in testing. They have 24 units going out in a week and then they will build a production run shortly after that. I believe the first of may they will be available.

Switcher on DC  - it's not the caps - it's the AC input rectifier bridge, instead of 4 diodes timesharing the AC input, it's only 2 on DC, and if they are near their design limit - poof!

I was not referring to the caps regarding 40Hz operation, not DC.  Actually, all bets are off on this unit under spec'd frequency range  as it's power factor correcting. 

Unless you're ready for smoke, I wouldn't try operating a switching supply on DC that isn't rated for DC input.  There are a variety of things in the control circuitry which might be relying on an AC source.

I did not know the iota's were PFC'd.  I sure missed that one.

I was referring to the 3000 watt, 48V power supply on sale surplus for $99 when I mentioned power factor correction.  It's on the first page of the specs with link posted above.

I don't know anything about the IOTA chargers.

Yellowhead sent me a note questioning my comment on power factor correcting circuitry.  I did some research on PFC chips and applications this morning and I think he is right-  a PFC front end on a switcher should be helpful for low frequency operation (bulk storage cap is less affected), and is not inherently problematic as I thought.

I had assumed most implementations of PFC would be AC zero cross and time based, but I was wrong. Of the three most common schemes, none would seem to care about AC frequency.

Thanks, Yellowhead, for your message and for forcing me to get a better understanding of PFC circuitry.

I finally got around to putting the metal film caps on my rectifier that Bruce recommended. I also put the negative battery connection all the way to earth. I've been putting 33-36 amps @ 54 vdc into the batteries for the past 4 hours with no display issues. I need more time on things for sure but this is a very good indication that Bruce's fix is going to work.

Bruce: There is no way I would have ever known about these caps and what they could do. Thank you very much for your help here and everywhere else on the forum. You truly deserve all the thanks I can give.

Thanks, Geno

That's good news!  ~2000 watts is a good charging load for a Listeroid.   Now can you write a simple wiring schematic of what you did, and post it for posterity and to sum-up your config?   Thanks.

Marcus

You're most welcome, Geno.  I really enjoy your creative projects and respect your contributions here greatly.  You are all signal and no noise, and that sure is a pleasure!

A cheap AM radio is a dandy tool when troubleshooting EMI problems.  You tune it between stations, and then it will squeal if a strong (primarily magnetic field) source swamps the receiver. A really nasty source will show up at high, medium and low positions on the AM tuner, even a foot or more away from the source.  The readings do actually correlate fairly well to spectrum analyzer measurements, often. For much troubleshooting and quick and dirty fixes, the $15 tool in the right hands is faster and  more effective than the $15K tool.

Radio Shack presently carries a model 12-586 ($15 online)  that has been tested by a friend at Los Alamos to be quite sensitive to a wide range of frequencies.  Some AM radios are lousy for this purpose.  The former Radio Shack 12-467 was also pretty good as a "near field sniffer".

The use of 0.1uf metal film caps around the bridge diodes is a cheap fix and dramatically effective in reducing that EMI.

I hope that your setup will continue to be a solid performer, and I'm glad my EMI guess seems to have done the trick.

Best Wishes,
Bruce

Thanks for the AM radio trick. I'd guess it would make a lot of noise near that old UPS. With its pathetic efficiency #s it will probably be out of there soon anyway. I'm losing ~10% (edit: It's more but I don't know how much yet) with the transformer, rectifier and charge controller. The other ~30% losses are all in the UPS. A few dozen more hours and I'll pretty much have proven the concept reliable though.

Thanks, Geno

Thanks for providing the diagram Geno! 

just so i am clear with what this schematic is for...

i assume it is for the st head?

is it for the excitation supply?

or is it for rectification of the output, so that it can be fed to an mx60 or flexmax80?

do the caps smooth the waveform? or do they clean up some harmonic crap superimposed onto the dc current?

maybe a short writeup where the problem is clearly defined, the solution presented, schematic posted
and the results... all in a nice "white paper"
it doesn't need to be very long, but would be nice to have it somewhere, where it won't get buried and is easier to find
later?

bob g

My ST head supplies 120 vac to a transformer which steps it down to 70 vac which feeds a rectifier which in turn feeds my Flexmax 60. At charge rates above 30 amps the display on the Flexmax went to garbage characters but the unit was still charging. Bruce suggested the caps in the pic be added and that I put battery ground to earth to reduce probable emi. The Flexmax is open between battery negative and ground for unknown reasons. (any ideas why?) Several hours of testing last night at 33-36 amps with no display problems. I'm about to fire it up again right now for a little longer test.

I'll put it in a white paper write up after a few dozen more hours run time.

Thanks, Geno

Quoteall in a nice "white paper"
it doesn't need to be very long, but would be nice to have it somewhere, where it won't get buried and is easier to find
later?

Yes, exactly, with a link to to the white pages section would be great.   Thanks for the schematic.  Helped me visualize much better.   I assumed it was for cleaner rectification of the output before entering the charge controller.

Also, BruceM, the 3 toroidal transformers arrived.   No doc's with them.   Just what the e-bay listing had:  "dual primary for both 100 -120 VAC or 200 - 240 VAC 50/60 Hz operation.  The secondary is 40 VAC center tapped at 30 ampere current rating.  It comes with two rubber pads, a top mounting plate and mounting hardware."   The transformer has a simple label:

I/P:  AC 110 V x 2 (GRN --- BLK)
O/P:  19.9 V (RED) -- 0 V (BLK) -- 19.9 V (RED)

You recall I was going to transform down 240 VAC from the ST head before a rectifier setup like Geno, then a choke.   Assuming I treat each green wire as one hot AC leg of 240 V and bond the 2 blacks to neutral?   How do I get up to 80 V?   Can't just stack transformers.   Do I put 120 V in one primary on one transformer and the other 120 V leg on the other transformer, and put the red leads in series since they would be out of phase?   That would seem correct.   Of course if I get the red leads backwards, there will be smoke, or hopefully just the breaker will do it's job.

Marcus

Thanks, Geno.   You posted while I was replying.

i don't see why you couldn't put the two transformer primaries seperately across each leg of the st head
or put them both in parallel connection 240volt windings across the 240 output of the st head
and then take the secondaries and connect them in series for 80vac

if you have the secondaries out of phase, the resultant voltage will be near zero, instead of 80vac
simple enough to check for and no chance of smoke as long as the the output legs are not connected together
which they should not be in any case anyway.

bob g

Geno-

It's a nice feature that the Flexmax has ground and negative isolated- that lets the system designer decide how grounding should be done. (Normally only in one place.)  In some systems, the positive rail is grounded.

I wanted you to do the grounding as I assumed that any input filtering on the Flexmax (small ceramic caps) would be to ground, so without the system grounding done, those filters would be ineffective.  I've also found that most digital systems are less EMI susceptible when not floating relative to ground.   I suspected the bridge as a problem EMI source because the spike or transcient type partial failure of the digital electronics happened only at higher currents- and bridge diode noise also increases with higher current.  I also expected that there was little input filtering on the Flexmax, since it would normally be connected to a PV array.  The designer was not expecting a "noisy" source.

Marcus-  I'll draw you a wiring diagram and will post it later tonight or tomorrow AM.  I'd wire the two transformers each for 240V (primaries in series), and then all the secondaries (4) will be put in series to get you to 80VAC.  As Bob notes, you will have to check the phase of the secondaries before connecting them. All red wasn't a big help, but you can manage anyway, and the price was great.

Marcus- Here's my wiring diagram from the wiring info you gave me.

Make sure to test the phase of the primaries and secondaries before connecting them. If you need help doing that, I'll be glad to try and help.  I'm afraid my writing skills suck.

Thanks both mobile_bob and BruceM.   Sounds like you both are saying the same thing.   The wiring schematic is especially useful -- I have a much easier time with a schematic than a description.   I tried hooking up 120 V to one primary this afternoon and got about 44 VAC across the 2 red leads, which gives 88 VAC in series. You are correct on your diagram about the input to each primary as 1 black and 1 green wire.   I tested it with an ohmmeter and have no resistence btwn the appropriate black and green wires forming a coil.   Pardon my ignorance, but how do I know which green/black pair to connect together?   Maybe the order they exit from the transformer is the same as the schematic (blk-grn-blk-grn).    And also, on the secondaries side, how do I check phase with just a simple multitester?   Thanks.  Oh, and I found a huge old transformer to use as a choke.   The guy said I could have it for free, but it must be 100lbs+.

Marcus

the secondary side is easy,  connect the two in series and check the voltage output on the two open end wires
if you have ~88 volts ac, you are in phase, if you have something very close to zero you are out of phase.

series connecting outputs are the easiest kind, they result in no possibility of smoke and sparks, provided you leave
the two output leads open for testing

paralleling outputs is where you can get into trouble, in which case you connect one of each coil set together and then measure the
voltage on the two remaining, if there is anything other than nearly zero, you will get smoke if you connect them, because they
are out of phase with one another, if the voltage is near zero they are then safe to connect together and use.

if you ever have any doubts use a small fuse holder and a 5amp fuse to connect with, a blown fuse makes a little flash, might spook you a bit
but won't fry anything other than very small transformers (much smaller than what we are working with here)

the transformers i am working with are all polarized color coded leads, the secondary has red and black 8 guage leads, the primary has a black and a white pair of 14 guage leads and another pair of 14 guage leads that were used to some sort of trigger or feedback to the inverter they came out of, in my application they are unneeded and will simply be taped off.

bob g

bob g

Thanks Bob, that makes the secondaries easy.   I'm not connecting in parallel, so nothing to worry about.  I'll just put a wire nut over the black lead on the secondary, and connect in series.   If zero volts then switch leads.   Simple.    What about the primaries?

if you have primary coils that are two pairs of green and black wires
and you are wanting to feed the transformer with 220-240vac

check for continuity and match up one green with a black to identify each 110-120 coil
then take a green from one coil and connect it to a black of the other coil

this will leave one extra green and one extra black wire hanging loose, those  two wires will now
be connected to the 220-230vac line.

to verify that you have it right before you connect to power,

while you are sorting out the two coil groups with your ohmmeter,
write down the resistance of each coil, you don't need highly accurate number here
you will find it to be X ohms

after you connect the green of one coil group to the black of the other coil group for series connection
remeasure the resistance of both groups as connected by measuring between the remaining green and remaining
black wires, you should have a reading of very close to 2X ohms.

if you have no continuity or infinity ohms, you have something wrong, go back and recheck
if you have X ohms, you have something wrong as well, go back and recheck

its late, and i think i have this right, i am sure Bruce will step up and correct me if i am wrong.


bob g

Bob's wiring diagram for the primaries is wrong, he has the two 240V configured transformers in series. 

For no load wiring testing, a 2 amp fast blow would be less exciting. 
Here's my abbreviated attempt at directions:

1.Wire and confirm each transformer primaries with 240V input, checking output for 40V. If not 40V, rewire.
 
2. Connect both transformer primaries to 240V (parallel)
Wire secondaries in series.  Confirm 80V, if not, rewire.

3. Carefully mark the leads so you can rewire this easily later.

Now you're ready to find a bridge and heatsink.

The 100lb transformer might make a hell of a choke.
I'd love to measure it on my Inductance meter.

Bruce:

please take another look at my diagram
the primaries of the two transformers are connected as series/parallel

T-1 has two primary windings and they are connect in series so that they can accept 220-240vac
T-2 is the same...

T1 and T2 as connected seperately are then connected in parallel so that they can both share
the 220-240vac line voltage

so what is wrong with the diagram?

it is not drawn incorrectly as far as i can see.

T-1 and T2 are connected in parallel as shown, not in series as you stated.

bob g

ps. i should have also stated that the use of a small rated fuse as Bruce mentions is always a good idea when
reconnecting any transformer, you never know when and if something gets mismarked or connected incorrectly
and a large flash results that scare the crap out of you... a small fuse makes a small flash and a relatively uneventful
and non damaging event should you get something wrong.

the input side of the transformer set should be fused anyway, so just use a small fuse at first to get the wiring sorted properly
is the best approach, after you get it right you can then replace the fuse with one of appropriate size.

i do this 220/440 dual primary and often dual secondary transformer thing with some regularity with control transformers
in large 3phase equipment, control transformers are generally always single phase taking power off of one leg to neutral of a three
phase system that might be 440, 460, 480 3phase or 208, 230 or 240 3phase. the transformers are made with dual primaries so that
a single transformer can be used in any of the 3phase systems at either high voltage (series connected) or low voltage (parallel connected)
with the same on the secondary side to get what is generally 24vac control voltage for the system. this allows a reduced inventory for the suppliers
basically a one size fits all sort of thing.

My apologies and thanks Bob.  I'm having a rough time with vision and trying to read my computer display this week.  Your diagram is perfect.

Thanks gentlemen!   I'll try it tomorrow.   What you really did is reassure me that I cant do anything too bad.   And I'm actually hooking it up to output from the batteries/inverters which has breakers.   The breakers are 20 amp though, so I'll try to put a fuse inline first.   BTW, your last diagram, bob, is excellent!

I almost had withdrawals after being away from the forum for 2 days.   We went camping at our land for the night.   

So, I didn't blow anything up, and the transformers are hooked up correctly, it would seem.   Output 88 volts AC total.   First time around I got 0 volts, so the red leads were crossed.   Fixed 'em and labeled correctly.    Now, we just need a bridge rectifier and heat sink.

Thanks,  Marcus

That's good news. You're getting close. My flexmax display issues seem to be gone but my UPS doesn't like surge loads when it's all warmed up. I've popped the breaker 3-4 times now.

If you build your own rectifier try to find diodes with longer studs than the ones I used, or a thinner heat sink. The insulated diode mount kit is mouser part # 526-NTE439. I looked for a long time and Bruce finally got me the #. Their web site is rather daunting for the inexperienced.

Thanks, Geno

Marcus, I would also suggest that since these solar charge controller's aren't expecting a "noisy" source of DC, that you go ahead and add the 0.1 uF noise suppression capacitors to your bridge diodes, also.  I can help find those parts at Digikey if you are going that way for the diode bridge parts as well.

Thanks Geno, maybe I don't need a big inductive choke.   Keep us updated on the long term stability.

QuoteI can help find those parts at Digikey if you are going that way for the diode bridge parts as well.

Yes, please, Bruce.  Any suggestions are welcome.  Geno's noise filtration is easy enough, also.   Do you have any rec's regarding a simple auto transfer switch for shutting off input from the solar panels when running the Listeroid.   Or do you see a big problem with both on the same charge controller?   I would guess it would be better to isolate the two.

Thanks, Marcus

Most PV setups will already have a night-time current blocking diode before the solar charge controller.

This is sufficient isolation, I don't see any problems with paralleling your rectified and filtered DC with the PV output after the diode. 

OK, Digikey is a daunting website!

Here's a metal film capacitor that is appropriate and cheap.
Digikey # P10730-ND

Their parametric search is sometimes a study in frustration. The catalog is about 4" thick, all fine print!

I think your bridge has to carry about 30 amps maximum...I'll look for that now.

Lloyd, yes.   That why we used the toroid transformers to drop the ST head voltage down to 80 VAC before the bridge rectifier.

Quote from: mbryner on February 16, 2010, 11:49:04 AM
Lloyd, yes.   That why we used the toroid transformers to drop the ST head voltage down to 80 VAC before the bridge rectifier.

Sorry Marcus, I deleted the post, on accident. What if the PV is at full ouput at the same time as the gen, wouldn't the charge controller see over-voltage and exceed the amp?

If that is the case I know you can stack 2 controllers.

Lloyd

Someone with a greater electronics background will be able to give a better answer than I can, but if I'm putting the generator charging circuit in parallel with the PV panel, how would it sense overvoltage?   (The PV panel max is <100 VDC, while the generator will output slightly higher rectified VDC.)   How it affects the MMPT circuit in the charge controller is beyond me.   Current should be limited by electronics in the MX80.   And I'm planning on running the generator when the sun isn't shining enough (rain, too little sun in winter, etc.).

Here's a bridge rectifier module:  digikey # CC1656-ND  

It's rated double your max current, but that's not bad in my book.  

You can save some money with post type diodes as Geno did, but then you must find the mica isolators, and a suitable heat sink.  The brick type module would save you a bunch of time.

Now you just need a big heat sink to mount it on, and use some thermal grease.  

Do an ebay search for big heat sink.  There's one guy selling new heavy aluminum finned heatsinks, in various sizes and widths.  I've used his stuff- it's nice quality.

Llyod- the AC charger voltage is limited, and the two voltages aren't additive.  

Hi Bruce,

I must be missing something.

I thought Marcus was, rectifying the ac from the gen to dc to feed the charge controller to then charge the bat.

Now it would seem that if the PV is feeding it's max voltage at the same time as the gen is feeding the same charge controller it's rectified dc voltage, then the controller is going to exceed it's rated voltage.

What am I missing? I better go back and re-read this topic.

Lloyd

Quote
What if the PV is at full ouput at the same time as the gen, wouldn't the charge controller see over-voltage and exceed the amp?

Charge controller is about 130 - 140VDC max, but don't let your AC ripple trigger the 150V warrenty void flag.

The controller will limit it's output current to a safe range, the Outbacks usually thermal limit before you reach the amps limit.

i'm not sure what the PV's will do with "lumpy" DC comeing, if the peaks will try to back drive them or what, maybe a blocking diode on the feed from the PV so the DC does not screw with them, or use 2 seperate charge controllers, or genset at night, early AM, and PV only when daylight.

Yes, you have the config correct, but think parallel not series input to charge controller.

Thank you very much Bruce, you're awesome!

mike90045, see few posts back same thread about blocking diodes in PV panels, something I had forgot about.   Two separate charge controllers would be too easy, and too expensive.

Marcus- here's a used bridge module for a good price on ebay
180468944390

Marcus is going to inductively filter his DC, so volts are going to be 80VDC with little ripple. The inductive filter also gives him a good PF.

Llyod- imagine a 24 and 12 volt supply,  with a common ground.  Put a diode on the 12V so it can't back feed. Now if you hook the positives together, after the diode, what would an applied load see?  Still just 24V. 

Arrgh.   Just thought of something else.  The toroid transformers limit will be 2400 watts.   The charge controller is set up to take the full 3400 watts from the PV panels in full sunlight.   Will I have to throttle back the gen input to the charge controller somehow?

Thanks, Marcus

If there is no current draw limiter on the solar charge controller, we'll have to limit the current draw externally.  Let me go look at the MX60 spec.

Quote from: mbryner on February 16, 2010, 12:46:05 PM
  Will I have to throttle back the gen input to the charge controller somehow?

Nope, throw all the amps at the charge controller, nearly all MPPT designs limit the output to within the safe margins (amps or thermal)

Mike, it's not the MX80 charge controller I'm worry about.   It's the risk of overdrawing the toroid transformers btwn the ST head and MX80, which are only going to give me 2400 watts.   If I had a 4th transformer, the problem would be solved, because the charge controller could do the current limiting.   But, alas, I have only 3 transformers.

Yep, Marcus, that's a problem. I forgot that you were planning such a big PV array.  The toroids will typically do 20% over rated on 60Hz without getting too hot.  But that's still not up to the capability of your PV array.

I checked the MX80 manual-  there are no tricks available there- just a fixed programmable max current out.  Manually reprogramming the max current out would have to be done every time you wanted to run the AC charger.

So if you can't live with an output that limits your input to the capability of the charger, then we either have to add current limiting to your charger's output or you'll have to get one of the $200 charge controllers just for the charger.  I'll have to think about the current limiting;  it may be more than $200 worth of work.  

PS-
What is the maximum AC load your Listeroid can sustain continuously?

Marcus, I don't know how familiar you are with the Flexmax control panel but it only takes a few seconds to change the charge amps. Just put a little chart on the wall with what you need from each source....and don't forget. I have a whole regime for starting and stopping the "system". Valves, pumps, breakers, etc.

Thanks, Geno

Quote from: mbryner on February 16, 2010, 12:46:05 PM
The toroid transformers limit will be 2400 watts.

Throttle back the genset ?  Different pulley ratio ?

Quotewith the Flexmax control panel but it only takes a few seconds to change the charge amps. Just put a little chart on the wall with what you need from each source....

That would work fine for me, but how would my wife remember to do all that.   As it is, she can't start the Listeroid alone consistently, which is why I'm building an electric start.   It's going to be hard enough for her to remember to oil it!  :)   Don't you guys have problems like this, too?!  :)

P.S. Bruce, I've never loaded my 6/1 more than about 3500-4000 watts.   A 2nd charge controller wouldn't break the bank, if that's what it takes.  Just don't tell me to get another MX80!   I mean, a little cheaper would be nice...

Morningstar TriStar 45 Amp MPPT $412 http://store.solar-electric.com/motr45ampmps.html

Morningstar TriStar 60 Amp MPPT $520 http://store.solar-electric.com/motr60ampmps.html

Xantrex XW MPPT 60 Amp  $530 http://store.solar-electric.com/xaxwmp60amps.html

Outback Power FM60 MPPT 60 $598  http://store.solar-electric.com/ouchco.html


This is where I got my TriStar 60 Amp MPPT, should be hooked up by the end of this week, if the rain allows the trenches to be dug. 

I'll think about it some more, Marcus.  Earlier in this monstrous thread or another, we found a non-MPPT charge controller that was $200.  It's a Tristar60 also, but not MPPT, which doesn't matter for this application. 

Here's the $200 Tristar 60 unit:  http://www.wholesalesolar.com/products.folder/controller-folder/tristar-60.html

Let me sleep on your current limit issue and see if I can think of another solution.

Non MPPT chargers (PWM - Pulse Width Modulation) work by directly connecting the input (PV or generator) to the battery terminal.  The lower the battery voltage, the more time the terminals are connected [ by a FET ]. Max source current will flow till the FET or FUSE burns out.  The fet also works as the nighttime blocking diode. 

Are the transformers really rated in max watts or do they have a max current? my logic is here you will be doing half the amps at the toroid's that you will be doing going into a 48 volt bank. Also for an interesting project like this we at MidNite solar may put you on a short list of First run pre production units for a reduced cost. Shoot me a quick pm with a few highlights of the project and I will see it gets to the rite people. This program was designed for industry professionals but we intend to open it for a few interesting cases to help us make a better mouse trap.

I should also state there will be 3 voltage limits a 150vdc a 200vdc and a 250vdc here is a little primer on the Classic's progress.  http://www.midnitesolar.com/pdfs/officialMidNiteSolarClassicwatch.pdf

From the ebay listing:  "It has a dual primary for both 100 -120 VAC or 200 - 240 VAC 50/60 Hz operation.  The secondary is 40 VAC center tapped at 30 ampere current rating."   Doesn't say any more on the label on the transformer itself either.   I'll PM you halfcrazy.

Mike's post made me check the Tristar 45 and 60 to see if they had charge current limiting on the bulk charge phase.  It looks like they do not, unless that is one of the PC RS-232 software programming options, which seems unlikely. They only do PWM after bulk charging is complete.  So the Tristar PWM controllers would not be useful for this application.  Thanks Mike.

PWM IS used for current limiting, Mike, it's just that these units have no bulk charge max current limiting, they are only doing the fixed voltage charging phases by PWM. 

I'll think some more about other means of current limiting.

Quote from: BruceM on February 16, 2010, 08:09:18 PM
Mike's post made me check the Tristar 45 and 60 to see if they had charge current limiting on the bulk charge phase.  It looks like they do not, unless that is one of the PC RS-232 software programming options, which seems unlikely. They only do PWM after bulk charging is complete.  So the Tristar PWM controllers would not be useful for this application.  Thanks Mike.
WM IS used for current limiting, Mike, it's just that these units have no bulk charge max current limiting, they are only doing the fixed voltage charging phases by PWM. 
I'll think some more about other means of current limiting.

PWM does not limit current. It limits the TIME the current is applied. 
The FET is turned Full On or Full Off, it can't be set to 82% on. It can give the effect of being throttled to 82%, but it's full power for only 82% of the time. 

Looking at the MS 45 & 60 MPPT controller, they output full array power in bulk.

If you use the 45MPPT - it will self limit in Bulk, to 45A   Which may meet your transformer power spec.

Mike, PWM is used for current limiting in virtually every SMPS out there, including the DC supplies in the PC you're using.  An inductor is used to limit the instantaneous current (current averaging); it can be on either input or output.  So current is really being regulated- the load or source, depending on the design, does NOT see high current pulses.  I hope this make sense to you now.

In our case, we will have a huge inductor on the input to Marcus's MX80. The AC supply won't see current pulses at all.

For high frequency switchers, the inductors get to be very small, thus the ever increasing speeds of switch mode converters and supplies.

I'll have to dig into my Trace C-12 again, I don't think there is an inductor in it.  Just the FETs, at a high fq switch rate at absorb and float.

What is SMPS - switch mode pwr sup?  Yes, those are full of chokes and transformers, and that's how the MPPT chargers work, in buck mode.  The upcoming Midnight Classic will have buck & boost modes, for even more charging options.

Yes, SMPS is switch mode power supply.  Without an inductor to do current averaging, a PWM PV charge controller would blow out radio reception in the whole neighborhood-  square wave power switching on a long unshielded wire (like a PV lead in)  is a no-no.  

Marcus, One approach to current limiting the AC charger input is to add an adjustable dropping resistor in series to your harmonic setup, so that you can have the extra resistor shorted by a switch or NC relay for AC operation, and open when charging batteries, so that your load is kept to the max wattage of your transformers.  This would not work with the boost type MPPT regulators, but would for the buck types like your MX80; as voltage drops to nearer battery voltage, current will be limited.

Another approach would be to have a mechanical switch or lever which would adjust the governor speed down to accomplish the same thing (only if harmonic regulator).

With an AVR, the 120V voltage sense circuit would have to be modified to allow regulation at a lower voltage.  A resistor switched in to the adjustment trim pot circuit would suffice. 

The other alternate would be a current limiting switching regulator on either the 240VAC side or DC side.  Not an option for your project, I think.

Thanks Bruce.   Those are good suggestions.      The resistor approach would involve a pretty big, hot resistor.    Why is the switching regulator not an option?  Cost?

One thing I hadn't mentioned because I don't have enough info on it yet:  I ran across a electrical engineer friend from the hospital in Lowe's on Sunday.   (We don't see each other enough, and like to speak Swiss German together.)   We got to talking and I mentioned this part of my project.   He says he has a "large" variac sitting at his house, but doesn't remember exactly how many amps or volts its specs are.   He'll be bringing it out to my land next Sunday and we are going to look at it.   It might be just the ticket?   If it has high enough amp rating and I can dial down the voltage, I may not need those toroids or a current regulator because I could just use the max current input the MX80 is set at (i.e. the 3400 watts of my PV array), correct?

A dropping resistor in the harmonic circuit is not that big and if sized properly, not that hot.   You only need a small voltage drop, and excitation current isn't that high.  Many of us already have a dropping resistor for harmonic operation.  About 10 ohms, 100 watt adjustable wire wound unit is my WAG.

A variac is an autotransformer- so there is no secondary winding and no transformer isolation.  This would be problematic for a 240V source setup as you must have one leg tied to your battery ground.  If your setup was 120V, the variac was 120V and neutral was already tied to the battery bank ground, then you could use a variac. 

The problem with a switching current regulator is that it would have to be custom built, I don't think it'sl likely find an off the shelf one.  You don't want to pay for custom engineering/fabrication work, it would make a second charge controller or a 240VAC-48V charger look like peanuts. 

Got it.

Re: a dropping resistor in the harmonic circuit: that's why I was commenting in another thread earlier:
http://www.microcogen.info/index.php?topic=614.msg7191#msg7191
Except I didn't know what size resistor to use, so I suggested using a dimmer and you replied recommending a variac.    If you think a 10 ohm 100 watt resistor is appropriate, I'll try it.

Re: a variac in the output:  IIRC, the battery bank negative is tied to bldg ground, which is also tied to PV ground and neutral in the breaker panel.    If it's a high voltage variac, that opens up another option.

Whew, this thread is ponderous, but lots of good info here, at least for me...

Remind me, please, what's the faceplate volts and amps on your ST-5.  I'd like to do a calculation before you order a dropping resistor.

I oversized and went with a ST 7.5, just to make it more complicated!   I'll look at it next time I'm out there, but stuck at work in hosp for next few days.

That's oversized, all right!  What I'll need is the rating on the field coil. 

OK, here are the numbers from faceplate on my ST 7.5:

120/240 Volts
62.5/31.3 Amps
60 Hz, 1 phase
Excite V = 61 V
Excite current = 2.7 A


But, I think I scored an even better find than those e-bay toroid transformers.   A great big autotransformer from an engineer friend, gratis.   Check this bad boy out:

(http://www.docbryner.com/4images177/data/media/174/1002-055.jpg)
(http://www.docbryner.com/4images177/data/media/174/1002-054.jpg)
(http://www.docbryner.com/4images177/data/media/174/1002-056.jpg)

It's built for 3 phase, but couldn't I just disconnect the transformers from each other and gang the secondaries together in parallel?   Then current limited by the charge controller, no?

Faceplate says:
Input volts:    480
Output volts: 0-560
Amps:    10
kVA:       9.7
Phase:    3

Since I don't know enough about these, why does it list 10 amps but 9.7 kVA?   560 x 10 = 5600.    Of course 240 x 10 = 2400 watts.   Or am I limited to the amperage coming out of the secondary?   Can I multiply by 3 for parallel connection, or is the faceplate referring to all 3 transformers in the existing setup, thereby limiting to 10 Amps total?   Showing my ignorance of 3 phase equipment and variacs in general.   I mean, I do get the concept of common lead, non-electrically isolated like a normal transformer, etc.

because it is 3 phase

5600 watts x 1.73= 9688 watts or 9.7kwatt


560volts per phase x 10 amps gets you the 5600watts

the power therefore in a three phase circuit is 1.73 times that amount

the forumla is

volts averge per phase x amps average per phase x pf (see note) x 1.73 = total power

*note*  pf= power factor, which is assumed to be at unity for the sake of rating, if the load is not unity the
kva will derate accordingly

bob g

There are two issues with variacs/adjustable transformers/autotransformers.

The first is that there is no transfomer isolation, so you don't get a floating AC output which you can reference to something else, like your battery ground.  With 240V input, this makes using these near impossible.  You'd have to apply not just 240V but also your neutral, to a balanced set of windings, appropriate to 240VAC (near half of the winding).   Then you'd have to use the neutral as your battery ground, and the ouput at your desired voltage from the neutral.  You may have to modify the unit to achieve this- you can check the various taps resistance to see how the windings have been divided.

Second, you will only get 10 amps out of each transformer, since this is an autotransformer, and there is no secondary winding to do a power conversion.  So if rewired for parallel, you will be limited to 30 amps total, regardless of voltage, or 2400 watts at 80 volts. 

It would avoid a dropping resistor in the field coil, or a mechanical governor speed reducing lever, if the first issue can be addressed successfully.

OK, guys.   Thanks.   I got all excited for nothing!  :)   30 Amps is what we have already with the toroids.  Now I have a big variac getting in the way.   Anyone want it?

So I guess we can continue with dropping a resistor in the field coil...

Two things about the variac- no excitation change, and you can use the toroid secondaries in parallel for a choke filter.  But whether you can get the windings sorted without modification is another issue.

My guess is that a 5 ohm resistor is about right, but I guess you can buy a 10 ohm adjustable and find out how far off I am.  You can buy some cheap 25watt values for testing...

I really like the approach of slowing down the engine (governor); that would solve the problem and give you a bit more fuel efficiency.  I'm not sure how to best do it mechanically...you need a simple lever type speed selector for the wife.

http://cgi.ebay.com/Large-Toroidal-Transformer-39-0-39-v-new-heavy_W0QQitemZ170397140538QQcmdZViewItemQQptZLH_DefaultDomain_2?hash=item27ac76063a

This seems like it might be a match for your existing toroid transformers, assuming it has dual primaries so it can do 240V in;go to  4 total  and then only your Lister is the limit to how much power you pump into your batteries. 

Marcus

if you end up not using the 3phase powerstat unit, and want to sell it let me know.

i could use it in testing of my modified alternators.

having that setup would be really handy in working out ratio's for transformers and for testing
different parameters.

thanks
bob g

OK, Bob, but how would I get it to you.  It weighs a ton.  >50 lbs.  You coming down through Oregon on I-5 anytime?

Bruce, I e-mailed the e-bay seller to ask if that toroid has dual primaries.   A 4th transformer would simplify the whole situation.  The charge controller would limit the Listeroid charging current to what it is set at the 3400 W of the solar panels.

sorry not coming to oregon anytime soon,

do you have a ups store? if so just take it to them and they will package and ship it.

let me know how much you need and i will get you the money however you want it,

the more i think about it, the more i think having it would provide a level of matching needed
to greatly simplify my testing.

bob g

Perhaps you should be watching ebay for a while to see if we can come up with a 3400 watt transformer solution, one way or another.  Just remember we can do series or parallel on the various windings.  Then use your existing toroids for the filter choke.

Something like this?

http://cgi.ebay.com/GE-Transformer-9T21B1008G02-480-Pri-120-240-Sec-7-5KVA_W0QQitemZ330407964497QQcmdZViewItemQQptZBI_Circuit_Breakers_Transformers?hash=item4cedd96f51 (http://cgi.ebay.com/GE-Transformer-9T21B1008G02-480-Pri-120-240-Sec-7-5KVA_W0QQitemZ330407964497QQcmdZViewItemQQptZBI_Circuit_Breakers_Transformers?hash=item4cedd96f51)

Yes, in 3KW plus sizes, a conventional transformer is pretty efficient.  you need a 240V primary, with 80 to 100V secondary. 

So, correct my math if I'm wrong before I buy it.

It has 480, 456, 432 VAC input (H4, H3, H2) and 240 or 120 VAC on secondary.  
432/120  = 3.6 ratio.  
So if I input at 240 VAC through H2 (432 volt input), it should output 66.7 VAC.  Perfect for rectification.
Would be limited to 7500 watts / 120 vac = 62.5 amps,
Or 66.7 x 62.5 = 4170 watts when charging via listeroid.  Just about right.

All correct?

P.S.  Bob, I'll look into sending the autotransformer by UPS.   Had thought of using it for stepdown transformer for high voltage hydro (eventually), but not having isolation sort of scares me.   Can't think of anything else to do with it...

Forget everything on the last post about the 7.5kw transformer:  Shipping to Oregon from Ohio is estimated at $355 !!!!!

what specifically are you looking for in a transformer?

what voltage input, and what voltage output? and of course what kva capacity

maybe we can find something a bit more local

bob g

Well, it has not changed since the beginning of this extended thread.   To recap:  I want to take 240 VAC from a 6/1 Listeroid w/ an oversized ST (7.5 kw), transform down to 60-80 VAC, rectify, filter and feed into Outback MX80 MPPT charge controller for 48 V battery bank charging when there is inadequate solar insolation.   I have 3400 watts of solar array, which is what the max current the charge controller is set to (should be at least).

I don't want to run the ST head at 120 VAC because I want to have it available at 240 V to bypass the batteries and inverters to run the house and well pump if anything goes wrong w/ electronics in the inverters, etc.

A good portion of this thread discusses using toroid transformers from e-bay.   Now there's the problem of nothing to limit the current:  the toroids that I bought would be max out at 2400 watts.

Don't want to have to flip a lot of switches.   Trying to keep it simple for the wife.

Looks like Bruce's idea of putting a resister in the excitation circuit may be best.

Thanks, Marcus

sorry to put you through memory lane, its just that this thread has got pretty long and sometimes the specifics
change from one end to the other.

so a 6/1 driving an st7.5, the limit of the 6/1 is about, what?  3.5kwatt?

would a 3kva transformer be big enough, or do you need 5kva (the next step up in size generally)?

what i am thinking is maybe we can find a 480/240 to 240/120 transformer in a 3kva or if need be a 5kva
and feed the primary 480v winding with 240 from your genhead, you would then have 60vac off the 120secondaries

if that sounds reasonable, i will keep my eyes open for such up here in the seattle tacoma area for ya.

bob g

3 kva and 5 kva are too small, unless my calcs are wrong.  ???

3 kva at 120 Vac is 25 amps rating, correct?
25 amps x 60 volts is 1500 watts, worse than where we are now.

5 kva at 120 Vac is 42 amps.
42 amps x 60 volts = 2500 watts, about the same as using the toroids I have already.

Both above calcs are using 4:1 windings ratio, i.e. the 480:120 v configuration to go 240:60.

That's how I came up with a 7.5 kva transformer.   If you find one, it would be appreciated.

Marcus's MX80 is NOT a boosting charge controller, so it would be better to have 80-100 volts, not 60. You won't be able to finish a charge with 60 volts, unless adding capacitance to the filtering, which screws your PF, and then the Listeroid won't be able to match the PV current.

A set of smaller transformers would also get you to 3400 watts, so watching ebay for a while might pay off.  The current set of toroids can be the choke filter, secondaries in parallel.

Nothing wrong with the relay or switch for dropping the ST voltage, either.

I don't know about operating a 440V primary on 240V, I haven't ever tried that. It seems unlikely to work at even half the rated wattage.

Bruce:

i am going to ask because i don't know for sure

what happens to the 60vac when you rectify it with a full wave rectifier?

does it not end up being 60 x 1.414 = 84.84vdc?

or does that fall off nearer to 60 vdc in a single phase system under load?

or after filtration?

bob g

Since I've been running through similar calculations for my system I thought I'd jump in.

Assuming the MX80 delivers the full rated 80A into a 48V nominal battery bank being bulk charged at 57.6V thats a maximum input power of ~4600W isn't it? So it might work with a 5kva transformer although I'd probably be inclined to bump up to 7.5kva as well; I hate running things at their limit (although you could argue the same for the MX80 in this case  :)

But if I understand all this correctly, the Lister will be blowing smoke long before the MX80 gets to pulling 4600W off the charger. So I guess we need a way to get the MX80 to back off before this happens. Assuming that dropping the current limit for the MX80 to say 60A isn't acceptable (and it would be less than ideal if you forgot to reset it and then limited the charging from the solar array) I'm thinking we need a way to start reducing the input voltage to the charge controller when the current reaches some defined limit. That way the MPPT tracking smarts can hopefully be persuaded to back off the charging current in an attempt to restore 'maximum power' to the batteries.

For the ST/rectifier/filter approach your are planning reducing the field current on the ST might be a way to persuade the head to start dropping the output voltage. For the switch mode power supply approach I am hoping to use it looks like I can drive a control input to achieve much the same effect ...

Or maybe I'm just confused  ;D

"I don't know about operating a 440V primary on 240V,"

I have a bit of experiance on this subject. The Plant's I work at (There is 2 on the same Road) have different Voltage services (#1 is 240 vac 3 Phase) and (#2 is 480 vac 3 Phase) at both plants we have
many machines of different voltages. We frequently swap transformers from shop to shop and often
use secondaries as primaries and vice versa. as well as use primary voltages lower and higher than
tagged.

We have never had a problem and even have been advised by the one of the transformer companies
that this is a common practice...

Rob

Thanks very much Rob, on the transformer info.  I've done secondaries as primaries before- but not primary at half rated voltage.  That will make finding a 3400 watt output unit much easier for Marcus.

Bob- With full wave rectification and a large choke as filter, AC volts out are equal to DC volts out. Some capacitance before the choke can be used to raise the voltage, but since Marcus is trying to get the max output of the Lister (3400 watts) then I wouldn't, as this lowers your PF.  In a pinch it will do the trick for a modest voltage increase; you have to use motor run caps, though, as nothing else can take the massive ripple current.

I use the method of switching in (dynamically) capacitors for regulating the output my 120VDC battery bank charger, but I'm only putting out 1824 watts (12A at 152V), so can afford the PF loss.
(I have multiple transformer taps that are controlled dynamically, also.) 

Marcus-  I forgot to mention, you were wrong on the transformer requirement and output calculation of the MX80.  The PWM buck regulation process gives you an inductive conversion of power, so that like a transformer, you will get close to watts in equals watts out. So a 5KW unit would be plenty. 

Yellowhead-  The MX80 has a programmable charge current limiting feature, which you can set to whatever you want.  Marcus would like to get his AC charger to match his PV system output of 3400 watts, so that the MX80 will handle it with no changing it at the keypad; his concern is for simplicity of operation for his wife.  This also has the advantage of reducing charging time and getting the best fuel efficiency out of the Listeroid. 

Quote from: BruceM on February 24, 2010, 04:36:43 PM

Yellowhead-  The MX80 has a programmable charge current limiting feature, which you can set to whatever you want.  Marcus would like to get his AC charger to match his PV system output of 3400 watts, so that the MX80 will handle it with no changing it at the keypad; his concern is for simplicity of operation for his wife.  This also has the advantage of reducing charging time and getting the best fuel efficiency out of the Listeroid. 

Apologies. I thought the solar array was bigger than the potential capacity of the charger. I just checked back to the start of the thread and I see that this isn't the case ...

FWIW, I've PM'ed the guy who was using that 48V power supply I mentioned a while back. He claims to be able to use it just fine for bulk charging a 48V battery bank so he must have been able to push the output to 57.6V (spec. sheet notwithstanding). Obviously not enough for equalizing though. I've opted to go with a 48V battery bank after all so I'll give this a go at some point in the next couple of months. If I get no luck (or smoke) I'll be chasing down the same path as Marcus ...

Yellowhead- For somewhat cold wet lead acid batteries (45F?), the cyclic charge voltage is about 15.2 volts. This gets to 60.8V for a 48V nominal battery.  So for winter charging, you'd want to start with at least 65 volts.  Unless you have one of the new fancy boosting charge controllers by Midnight Solar.

Here's just he 5KW transformer that's needed, 240V in 80V out.
http://cgi.ebay.com/Step-Up-Down-Transformer-5KVA-5-Kva-Output-80v-160v-GUR_W0QQitemZ360237030941QQcmdZViewItemQQptZBI_Circuit_Breakers_Transformers?hash=item53dfccde1d

that looks to me to be about the best solution yet, and where the heck would a guy find another like it?

and it is in california so shipping to Marcus should not be too bad?

i don't think i have ever seen one like that.

bob g

It's in Los Angeles.  I know it's not a super bargain, but it is exactly what is needed. 

after talking to Mark today,  about this project he reminded me that we have some SD5 generators

the sd5 is a dual use generator, looks like an st5 but produces 240 vac and up to 160amps of welding current

i don't know for sure what the open circuit voltage is but i bet it might be sufficient to charge a 48volt bank
and provide a bunch of amperage, certainly 60-80 or even 100amps would not be a problem.

i have never worked with one of these yet, we have 3 such heads and would part with one for a very good price
should anyone want to experiment with one of these for battery charging.

fwiw

bob g

Bob, That SD5 might be a real sweet setup for someone's off grid system. 

Bob what would you be looking to get? I may be interested in experimenting although I did hook 120 vac to my rectifiers and fed that into my 250 volt classic charge controller and it seemed to work fine I didn't push it past 40 amps output yet I wanted to get some software updated to give me a U pick mode first I was running in standard solar tracking mode.

What make and model is your "classic" charge controller, Halfcrazy?  That's pretty sweet that it can take straight rectified 120V.  Even if starting with 240V, it's easy to find 240 to 120 step down transformers.

as for cost of one of the sd5 heads,, let me check with my biz partner
he has one, and i have two

seeing how he was the one that suggested their use for battery charging, i want to allow him the first right
of refusal to sell, and get a price should he decide to sell.

if he tells me that he does not want to sell, i will then price one for sale.

what i would really like to have is an st5 or st7.5core, and would make a nice swap deal that would be fair.

i am thinking of rewinding an st5 or 7.5 for 12poles and replace the rotor with a custom clawpole lundell type
for ~400hz 3phase, , basically an oversized version of a truck alternator.

i think i could get 15-20kwatts pretty easy, although i really have no use for that much power, i do have the inverter
capacity to take that kind of power at 48volts nominal and put out very pure sine wave and rock steady no flicker power.

and i think i could get the alternator efficiency up to 85% plus without a huge effort.

or have the ability to run it at 600rpm for 60hz output, which might be useful for listeroid folks?

because of my physical limitations i am thinking of moving more into component development as opposed to complete systems
which i am now thinking may be of no use to me.

just trying to think ahead a bit
and look at my future from a realistic view

bob g

Hi everyone,

We were camping on our land for the past 2 days, away from the forum.    Poured the last lift on the concrete block (filled all the cells) today.   Big day.  Lot of fun, except for the rain.

Bob, your SD5 gen may be just the ticket for me.   I could be interested in a swap.   Do you have any more info on that SD5?

Marcus

i don't think i have anything on the sd5, but from memory it max's out at 160 amps, but at what voltage
i am not sure. i suspect it is probably around 30volts at full 160 amp load.

will have to look around this weekend and see if i can find any doc's with one of the heads, it all depends on how deeply they are stacked away.

bob g

Bruce I have all three models of the Classic controller from MidNite Solar. these 3 beta units are beta units I have been testing for MidNite for over a year. The units will be available to the public around may 2010. I was quite impressed that I got no display garbling or anything from the straight rectified ac. to be fair the ac was from the power co not a generator but I don't know how much difference that will make? I do intend to experiment with ac from my generator soon I should have updated software next week that will allow me to pick the target voltage I did not want the classic to do a sweep like it would on PV so I had to be careful. This is another nice feature software can be updated via usb cable or even over the home network or internet.

I'll be interested to see how you set the U-pick option and how it works. I tried it on my flexmax for a while and went back to sweep for some reason. Exact reasons escape me but I think varying voltage coming out of the rectifier had something to do with it.

Thanks, Geno

Thanks, Halfcrazy.  I should have remembered you are the Midnite beta tester.

Another interesting issue would be what is the PF of the Midnite unit (or any other PV charge controller) attempting to charge from straight rectified AC.  There would be no PF correcting in a design for a PV power source.

Halfcrazy and/or Geno - can you measure your generator AC power out and then your charge controller DC output? (Maybe Geno already did this and I forgot.) If not very close, that would indicate that the PF issue is significant, and the need for an inductive filter remains for these units.

Bruce, I haven't measured power the way you suggest but it would certainly be a good idea. I think I'll start discharging the batteries right now and do a test later.

Thanks, Geno

Thanks, Geno! 
Bruce

Listeroid 6/1 ST5
Killawatt on a current transformer.

There is a 75' run of 10 gauge cable to a step down transformer. It then goes into the rectifier which feeds the flexmax.

Killawatt readings
1470 watts
14.9 amps
117.6 volts
61.3 hz
Power factor .84

Flexmax readings in bulk charge mode
1250 watts
73 volts in
17.5 amps in
23 amps out
Battery voltage 52.8

I don't think the losses are to bad but if I could reduce them I wouldn't complain.

Thanks, Geno

looks like your overall efficiency is actually quite good in my opinion

the flexmax i figure maybe 94%
that leaves about 88% for the transformer and transmission line

for an overall of 82.6%

not bad at all in my opinion for the distance involved, the transformer and the flexmax

the st head is about 80% so

80% x 82.6% = 66%

don't know how you can significantly improve on that, using all those components,

what is a very good 120 or 240vac charger for 48volts nominal these days in efficiency?

i guess if it is much better than 82.6%, maybe it would pay out over time?

probably take a very long time in light of how pricey they can be

thanks for the numbers

bob g

Thanks so much for the lovely data set, Geno.  I know how much time it takes for this sort of thing and I know others, too, will also appreciate your efforts to share your pioneering work and data with us.

Your 75' cable loss should be negligible at 117V with only 14.9 amps on 10 gauge wire.

The PF (0.84) seen at the ST5 isn't bad.  The transformer inductance is helping here, I think. A choke filter would lower this, but how much of a difference in fuel consumption that would make is still not clear to me, since some say that those VA lost to power factor won't show up in fuel use.  Apparently I'm not alone in being dubious about that theory and Bill Rogers doesn't buy that yet either.

The transformer efficiency looks like 87%, which is what my textbooks predict for a good non-toroidal transformer of that size.  (Larger transformers are more efficient.) The transformer loss is made up for in part by it's positive contribution to PF.

The Flexmax efficiency is impressive- 95 or 97%.  There seems to be a typo on the input to the Flexmax (after transformer) data; I calculate 1277VA, you wrote 1250.  Either way, the Flexmax as a DC-DC converter is VERY impressive in efficiency.

So depending on whether you think VA's generated for PF losses are real ones, fuel wise, the total efficiency (1752VA or 1470 watts with .84% PF) is either 69.4% or 82.5%.

The PF could be raised with a choke filter, and the transformer efficiency could be improved 8% by going toroid, but it's pretty darned good as is.  Each  would only affect the total efficiency be a few percent. Without some proof on the PF-fuel issue, I wouldn't blow the dough for increased efficiency.

I do hope someday, some pioneer will nail down the PF-fuel use issue for us all.  One generator run (with measured fuel consumption for a fixed period of time) with a lousy PF and X watts load, one run with same X load but only resistive loading.

Thanks again, Geno, for your help on this.
Best Wishes,
Bruce M

as it relates to pf for our sytems

where lower pf shows up as costing you in fuel is when you push the circuit to capacity with kwatts (real, that are doing work) and then add the reactive component, this starts to heat the conductors in the generator, the transmission line and in this case the transformer,, when this happens
you will note some increase in fuel consumption. if the pf is for instance .9 in a situation as describe, moving it up to .95 is likely only going to show up
as a decrease in fuel of about a half a percentage point and not the full 5% as one might expect

even going from .8 up to .95 seldom returns 1% in fuel savings in most cases, and

if the kwatts real power, plus the reactive component is below that of the total capacity of the generator, the lines and in this case the transformer
there will be virtually no added heating, and therefore the added fuel burned due to lower pf will be very hard to measure.

this from my reading, and what i have been able to observe directly through experimentation.

typically capacitance is added to improve pf, not inductance, at least from what i have read, but
i don't know for sure that inductance can't be used, however

one is well warned not to start to add capacitance to any circuit feeding inverters, or converters in meaningful amounts, the results are damaged
electronics from what i read.. whether this is always the case i don't know , but probably something one ought to have the oem engineers involved
in the design and use of.

also the pf of Geno's transformer will improve to near unity the more load he applies to it, a lightly loaded transformer or motor exhibit very poor
powerfactor that improves with added loading and will peak with peak load.

my transformers i am am using in the 3 phase testing start out at about .4 pf at no load and get all the way up to .98pf at full load.

the problem with altering pf for a transformer is its dynamic nature, as the batteries come closer to charge the load will reduce and the powerfactor
will get worse, dynamic powerfactor correction would be the way to go, but

it is unclear to me as well whether the increase in pf would result in a meaningful reduction in fuel consumption.

my thinking is if you are using a 5kva transformer with a 5kw st head, driven by a 6/1 there probably is no combination of factors that would result
in peak kwatts of real work plus reactive component that would equal more than what the generator, transmission line and in this case the transformer could handle without significant increase in heating.

might well be a different story if the prime mover was a 12/1 driving the st5 and a 5kva transformer on the same 10gage wire, with a
load that was near 5watts and a pf of .84, then i would expect some heating (and probably a damaged st head) and extra fuel being consumed
to cover this extra heating.

my favorite subject, power factor and its correction

:)

bob g

Thanks Bob.   I did some more web research and reading on the subject tonight and now I'm convinced that PF correction isn't going to do much for generator fuel consumption.  For Geno's setup that means that for affecting his fuel economy, there is no need to add an inductor for DC filtering.

When I wrote about inductors helping PF correction, that is for primary filtering of a linear (non switching) DC supply only...for inductive loads like motors, inductance after the generator would  only make the problem worse.  When capacitors alone are used for linear DC supply filtering, a lousy PF results;  the same problem as with too much capacitance added for inductive motor PF correction.

Bruce,

thanks, that makes sense!

i really never gave much thought to power factor issues with switch mode stuff, mainly was more interested in motor loads
and that sort of thing.

it doesn't appear as though pf makes a significant difference in fuel economy in most applications, i guess it is something one
should be aware of, and if it is economically relatively inexpensive to keep the power factor up and the engine is required to run
long hours everyday,, maybe then it would save some fuel over the long run?

there are probably other reasons why having  a good pf is beneficial, if not for saving fuel.

probably the biggest argument for keeping the power factor high is you get more work down with the installed capacity.

if the 6/1 can only make 3.5kwatts, i would suspect getting as near 3.5 kwatts of work done with the power has a certain
attraction.

bob g

Hi Bruce, and the rest of the gang.

Bruce you may like this site, Bob I'm sure you will...and for everyone else looking for transformers.

http://www.toroid.com/custom_transformers/dc_filter_chokes.htm (http://www.toroid.com/custom_transformers/dc_filter_chokes.htm)
Toroid Corporation has developed a new concept for low frequency chokes based on its in-depth knowledge of toroidal design. Our chokes are smaller in size, have less weight, run quieter, and have smaller losses than ordinary chokes. The low strayfield also permits mounting of our chokes flush to the chassis.

I was just reading on another site about using torids for chokes as to capacitor, and that torids provide a smother/less ripple for dc rectification.

This is a great "Technical Bulletin No.1" Application Notes on Rectifier Transformers http://www.toroid.com/custom_transformers/technical_bulletin_1.htm (http://www.toroid.com/custom_transformers/technical_bulletin_1.htm)

Bruce, you may be a good one to decided if it's all corporate hype..but their price seem reasonable.

Lloyd

The #s on the Killawatt and Flexmax bounce up and down a bit with MPPT doing its thing so I look at them for a minute and guesstimate. I'll do a longer test today and record more data. Total kwh from the Flexmax and KAW should be useful. I don't have an easy way to measure fuel consumption. I'll think about that one.
My transformer is a 5 kva, 208-120/240 volt unit.
Flexmax efficiency graph. By sheer luck I was right at the peak.

Thanks, Geno

Llyod, No, it's not hype, toroids do perform better, and I have used this company's products myself and specified them for other projects for the last 18 years.  For non-custom transformers, Antek, who sells on ebay is reputable and their full load/no load voltage data has proven to be very accurate. For smaller toroids, Digikey carries a couple different vendors products.  For the smallest ones, I like Talema brand, which are made in India.

The only problem with toroidal transformers and chokes is the price; otherwise you'd see them used a lot more.  Because my epilepsy is affected badly by low frequency magnetic fields, I use toroidal magnetic products exclusively; the stray magnetic fields are dramatically lower than E-I cores.  You will rarely see toroidal transformers over 1000 watts; around that size is commonly the largest core.  

I'm sure your transformer stays nice and cool, Geno.  You sure have more capacity there as well as with the Flexmax, right?   Did you limit the charge rate via the Flexmax setting for max battery charge current?

It was nice that your setup came out right at the Flexmax maximum efficiency point!

Thanks again, Geno!  You've shown that Flexmax user's can get away without filtering the DC input, at least at moderate power levels, and with decent PF, too.  When I look at the prices for high current AC chargers this looks like a very good solution, and one that takes good care of the batteries, with the battery temperature compensation probe and 3 phase charging.

PS- the new Midnite Solar "Classic" looks very good for this use too,  and even the Tristar PWM units (the cheapest option) look like they could do a decent job.  Lets hope Midnight will add a feature like an external input to select a secondary charge current limit- that would make their "Classic" a real classic for this application, in addition to their wide input voltage options and voltage boost capability.

Geno:

i have a question about the numbers and the flexmate if i may

the input volts and amps,
and the output volts and amps

are they presented on the screen?
or did you measure these independent of the flexmate using other meters?

thanks
bob g

All my FM #s come off the screen. I can test the voltage's independently with my meter but not DC power. I do have a clamp on amp meter and will do some comparative AC testing with it today to see how close it is to the KAW. I suppose I could test the low voltage side of the transformer as well. I won't be starting the test till this afternoon. If there's anything else I should test for let me know and I'll add it to the spreadsheet.

Thanks, Geno

Quote from: BruceM on February 28, 2010, 04:17:29 AM
I'm sure your transformer stays nice and cool, Geno.  You sure have more capacity there as well as with the Flexmax, right?   Did you limit the charge rate via the Flexmax setting for max battery charge current?

I think the FM is set at 20A which gives me 1200-1300 watts into the batteries. I have 8, T105s and if I figured it out correctly I don't want to put much more than 150 watts into each one.

Thanks, Geno

Geno:

if you could test the input voltage and output voltage
as well as the input and output amperage on the transformer with your clampon meter
so we can compare to the killawatt meter that would be helpful

by most accounts the killawatt is pretty accurate in measuring amps, volts, hz and calculating watts, pf and kva

i just wish we had the same for the lower voltage DC side of things

the wattsup meter and the turnigy meter are the dc equivalents of the killawatt, but both are limited to 60vdc
a threshold that is very close to the 57.6volts that i test at.  personally i wish they had a limit of maybe 80-90volts
so we could get more useful testing done with one of them.

thanks for going to the trouble Geno, it is appreciated

bob g

No testing today. I had everything setup and ready. I shut the engine down to hook up a fuel tank with .5 gallon markings on it and the ST quit on me. I flashed it, scraped the brushes, cleaned the slip rings and replaced the rectifier. I don't have time to t-shoot further. I have to get ready to be away for a few days. It's probably time I take it into the shop for a full cleaning and rewire things to get rid of the doghouse anyway. What a bitch. I hope it's nothing too bad.

Thanks, Geno

Geno, that really sucks.  Murphy sure knows how to time breakdowns.  I hope it's something simple and easy to fix. 

if one of you guys ever get ahold of ole murphy, you hang on tight and i will grab a board and beat
the summabeech senseless..

sorry to hear about the st giving you fits, if it isn't one thing it seems like it is another.

bob g

I have a good 3000 hours on it and as long as it's something cheap I won't complain. I will complain and go find that Murphy guy if we get an ice storm in the next couple weeks. Moving that ST head the first few feet will a pain, it's in there pretty tight and things have gotten dirty.
I'm now off to Lk. Placid NY for a few nights on business. New computers at a client I've known for a long time. Good people. It should be fun. The resort I stay at is right next to down town.

Thanks, Geno

I remember Lake Placid, Geno.  A very beautiful part of the world.  Hope your job there is productive and fun.

Well, I only spent one night in Lk. Placid and Mondays are pretty quiet but it was still better than most places.

It appears my gen head problem was caused by a field cable from the rec to the brushes that was rubbing on something. It was worn just to the point where the wires were exposed. I didn't find it until reassembly. There was a fine coating of black greasy stuff all over the internals. I need to vent the engine breather asap, the old sock aint good enough. The doghouse is gone. It was quite time consuming to get it all clean, dried, moved, and mostly rewired. It's a heavy SOB. The only testing I'm doing tonight is some fuel consumption (it was all set up when the gen head quit) and some taste testing on a rack of ribs and some beer that's been buried in a snow bank for a while.

Thanks, Geno

Geno- glad it was something readily fixable!

Quote from: Geno on March 07, 2010, 04:51:36 PM
some taste testing on a rack of ribs and some beer that's been buried in a snow bank for a while.

I suggest heating the ribs before testing.

Quote from: mike90045 on March 08, 2010, 10:49:35 AM
I suggest heating the ribs before testing.

They were heated just fine thank you. Based on your avatar you'd know, those ribs must be scorched ashes by now. ;)

Thanks, Geno

I got to do a charge efficiency test today. The results are in the attachment.

Thanks, Geno

Hi Geno, Wery impressive.  Looks especially impressive for the lower wattage absorption phase, which is more KWH. Your transformers seem to be slightly overtaxed a bit at higher currents- I can't explain the greater efficiency at lower power levels otherwise.  I'll have to study the hardcopy of your data a bit more.  A toroidal choke might buy you some improvement at higher currents, as it would reduce the peak current demand on the transformer.  But I'm not sure it's worth the bother.




 

I'll do some more tests as time permits. As you know, repeatable results are what counts.

Thanks, Geno

Geno, I tried to find it in the back pages (!) of this thread but can't locate your transformer specs. I'm just trying to get a better understanding of why your efficiency is reduced somewhat at higher loads. I would have expected it to be the other way around. 

What specs do you have for your transformer?

Thanks for your data, time and for helping us all learn from your very successful ST to Flexmax charger project!

Best Wishes,
Bruce

Quote from: BruceM on March 13, 2010, 09:29:04 PM
Geno, I tried to find it in the back pages (!) of this thread but can't locate your transformer specs. I'm just trying to get a better understanding of why your efficiency is reduced somewhat at higher loads. I would have expected it to be the other way around.

Best Wishes,
Bruce

I agree but I'd like to get a few more runs in before I draw any conclusions.

I don't think I ever posted the xformer specs.

Input on H1/H4 Output on X1/X4 with X2/X3 shorted. Mistake
X1/X3 and X2/X4 shorted and their the outputs.

Thanks, Geno

Hi Geno, What is the VA rating, or current rating of this transformer?

Driving H1, H2 with your 120V nom. output will give you about 64% of the rated VA output.

The transformer does see the full VA load, so this is one place where PF does factor in.

So I'm wondering if at around 18 amps output if the transformer is overtaxed; if it is rated less than 2200VA, then that is likely the problem.  If not, then watching via oscilloscope a shunt resistor(0.01 ohm)  in the post rectifier(DC) line to the Flexmax might tell us something about what the real time Flexmax current draw looks like. 

Oops, didn't notice that was missing.
5 KVA

Thanks, Geno

Thanks Geno. With that much headroom, we don't have to worry about the transformer. 

Given the lumpy DC, perhaps the Flexmax is a just bit off on it's calculations. 

Quote from: BruceM on February 11, 2010, 10:17:28 AM
Yellowhead sent me a note questioning my comment on power factor correcting circuitry.  I did some research on PFC chips and applications this morning and I think he is right-  a PFC front end on a switcher should be helpful for low frequency operation (bulk storage cap is less affected), and is not inherently problematic as I thought.

I had assumed most implementations of PFC would be AC zero cross and time based, but I was wrong. Of the three most common schemes, none would seem to care about AC frequency.

Thanks, Yellowhead, for your message and for forcing me to get a better understanding of PFC circuitry.

I have this in service as of this morning. I eventually went for a 48V system so I bought 2 of the PFC corrected power supplies and wired the outputs in series to get 96V into the charge controller. This seems to work just fine and I can throttle my set back to about 1400rpm which subdues the Changfa roar a bit :) Below this the power supplies drop the AC input. I still need to figure if this is because the AC frequency is below spec. (47Hz) or because the voltage from the head has dropped too much. It gets down to 160-170 at 1400 rpm which is also below spec.

I'm going to add AVR to the head to see if I can hold the output voltage up at lower rpm. If this works I'll try dropping towards 1200 rpm and see if everything still hangs together. I can't see going any lower as I'll be running out of hp and I'm worried about the thumping on the coupler and the reduced cooling in the head. Still I only need ~3kw in bulk charge so I might be lucky ...

FWIW the reason I want to do this is that my set is (for better or worse) direct drive and at 1800 rpm it simply makes too much power for battery charging without a substantial diversion load.

Either way it looks like the use of 2 of these power supplies connected in series is a viable alternative to a passive approach using transformers/rectifiers/chokes etc.

Simon.

Quote from: Geno on March 13, 2010, 04:36:34 PM
I'll do some more tests as time permits. As you know, repeatable results are what counts.

Thanks, Geno

Is the setup you have capable of using more of the available watts that the genset can produce?  Or do you have it limited in the flexmax due to the size of the battery bank? 

Quote from: Geno on February 28, 2010, 04:51:23 AM

Quote from: BruceM on February 28, 2010, 04:17:29 AM
I'm sure your transformer stays nice and cool, Geno.  You sure have more capacity there as well as with the Flexmax, right?   Did you limit the charge rate via the Flexmax setting for max battery charge current?

I think the FM is set at 20A which gives me 1200-1300 watts into the batteries. I have 8, T105s and if I figured it out correctly I don't want to put much more than 150 watts into each one.

Thanks, Geno

:-[I found the answer.  I didnt read back far enuf...

Quote from: mbryner on February 16, 2010, 02:18:58 PM

Quotewith the Flexmax control panel but it only takes a few seconds to change the charge amps. Just put a little chart on the wall with what you need from each source....

That would work fine for me, but how would my wife remember to do all that.   As it is, she can't start the Listeroid alone consistently, which is why I'm building an electric start.   It's going to be hard enough for her to remember to oil it!  :)   Don't you guys have problems like this, too?!  :)

I do!!!!!!!

I think my wife would just let the batteries go flat before she'd even consider starting the listeroid. I've tried giving lessons, however we didn't get to far.

Quote from: Tom on June 15, 2010, 07:07:16 PM
I think my wife would just let the batteries go flat before she'd even consider starting the listeroid. I've tried giving lessons, however we didn't get to far.

we may have the same wife  :o ... or maybe they are sisters  ;D

Hello Gentlemen,

Since I started this thread, here's an update.   I've only been on the forum occasionally in the past 6 months and I've missed it.  

Our house construction is nearing completion and hopefully we'll move in in the next few weeks!  :)    The construction crew wouldn't even know they were off-grid if they didn't see the solar panels.  I didn't have time to think about this thread until recently...

The power system functioned flawlessly until about 2 weeks ago when we had our first early autumn rain.  The tile guys had 500 W halogen bulbs burning brightly all day, etc.   The solar panels couldn't keep up in the cloudy weather of course.   So I had to start the Listeroid 6/1  when the batteries got down to about 60-70%.   It charged the batteries at max charge rate back through the Outback inverters.   But, whenever the guys would try to start a big saw, etc., their equipment would kick-off because of too low voltage.    Now I'm getting leery of living in my house, having low batteries because of rain, and not being able to run, say, the vacuum because the generator is running.

So, I'm going back to my original plan of faking out a charge controller into thinking it's getting DC from panels when it's actually getting rectified current from the generator.    I'm installing a few breakers at the generator to select between 230 VAC and 120 VAC output.   Then I'll take the 120 VAC output to a high current bridge rectifier, then through an inductor/choke filter.    V DC should be close to 120 V, correct?   (i.e. Should be close to the RMS AC Voltage after going through the choke.)   To get even lower voltage, I'm adding a tiny key-ring loop to the governor spring on the Listeroid, effectively decreasing spring tension which would decrease RPMs, but would be simple to change back to normal voltage.   A rheostat on the field winding would work too if I find the right one.    I ordered the rectifier and it should be here in a few days.

Never did find a transformer (see a few pages back): the shipping was always the deal killer.

Still don't know about limiting the charge current, but what harm can I do by hooking it up?   If the Outback MX80 draws too much current, the Listeroid will bog down, voltage will drop and the charge controller will eventually disconnect.   Of course, if no one is watching to turn it off, it would try to reconnect and would cycle like that continuously.   Using a 2nd charge controller would be another option, but the PWM controllers won't work because they only limit current to a certain point, then disconnect.   From the TriStar-45 manual:

"If the solar input exceeds 100% of the controller's current rating, the controller will reduce the average current below the TriStar's rating. The controller is capable of managing up to 130% of the rated solar input. When 130% rated current is exceeded, the solar will be disconnected and a fault will be indicated. The input FET switches will remain open for 10 seconds. Then the switches are closed again and charging resumes. These cycles can continue without limit."

Updates will be posted in the next few weeks as I experiment again.

I know, you guys are saying, "he didn't fix the dumb thing already 6 mos ago?!?   :)

If you want to see pictures of the house (from about a month ago):
http://www.docbryner.com/4images177/details.php?image_id=8390

Thanks,

Marcus

P.S.  mobile_bob, I still have that big Variac.   Thought I'd use it for something, but never did.   You still interested?

That is going to be a lot of ripple rectifying single phase 120VAC to DC.  I will be curious to see how it works out feeding your inverter.

Don't the outback inverters have chargers in them ?  What model inverter ?

Marcus:
nice to see you back, alive and kicking!

trying to remember the variac, was it the three phase unit?

bob g

Hi MarcusB.
Your house pictures are looking great. A very Swiss-American home! Just had to get the tractor in there too, eh?
The kids are sure getting bigger too.
Looking forward to seeing pictures of your mass hearth wood heater.

Regards
Steve Unruh

Marcus,

Welcome to my world. We've got a 3.4 kw solar array on the roof and s listeroid 6/1 too. Ours was used without the solar panels for 99% of the construction because we mounted the array on the roof. The system is currently setup to charge through the out back vfx3648 inverters that are wired out of phase to feed a standard utility panel. The only real problem we encounter is that if the micro wave or jet pump turn while the generator is running it will lower the voltage enough to cause the inverters to drop out of charge mode and then in a minute they will reconnect. I had expected the inverters to come with "Generator Support" however although the menu item is there it is not functional. Had the generator support  been functional when the load exceeded the max amp set point the inverters should have synced to the generator and switched to inverter mode until the load dropped and the inverters would return to charger mode.

I have contacted Outback about this without reply and am quite disappointed in how they have handled this. I've even wrote a correction to Home Power magazine about their article stating that the Outback inverters will do generator support and no reply from them either.

So assuming you have outback inverters you are stuck as am I. Please keep us informed as I am thinking of doing something similar to you with our system.

Hi Tom,

hee hee, we have exactly the same setup.   What kind of charge controller are you using?   Can it handle high voltage V(oc)?   I just drove through Hopland a few weeks ago.

I can't be out at the house jobsite every day, so having the solar panels working was a necessity.   My contractor doesn't know much about electricity (funny, huh?), so he couldn't be starting the Listeroid every day and throwing switches.   Yes, if only the inverters would drop charging mode and go back into inverting mode when you turn on a heavy load, but my guess is they can't sync fast enough.   Here's my current plan:

So, this long thread started because I wanted to get away without making a ST head mod,   but it looks like a system of 2 breakers  will be necessary to convert between 120 and 240 V operation because transformers are expensive.  One breaker can jumper U3/U4.   The other breaker has to be a double pole breaker: one pole to connect U1/U4 and the other pole for U3/U2.   Make sure you *never* have both breakers switched on at the same time.    In both cases either U3 *or* U4 can be neutral, and don't bond neutral to ground except at the main panel.

The 120 V option completely bypasses the inverters, with output going to the high-current bridge rectifier.   Here's the one I bought (1000 Volt, 100 Amp):  
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=170546493063    
It's 3 phase but will work fine for single phase also.   I have a giant old transformer for a filter choke to smooth out the ripple that ronmar was alluding to.    Geno a few pages back confirmed that the Outback charge controllers can handle rectified DC.    The whole thing is a couple more switches/breakers than I wanted but it is cheap to implement.

The 240 V option is for emergency feed to the main panel and back into the Outback inverters (i.e. the current setup).

Marcus

p.s. mobile_bob:  yes, 3 phase 9.7 kva autotransformer    See page 10 of this thread or:  http://www.microcogen.info/index.php?topic=500.msg8470#msg8470
Come pick it up!

Marcus,
Your house looks great!
I want to charge from my 6/1 through my ST-5 to a TS-60 to my batteries to supplement my PV and hydro when needed so I'm glad you guys are figuring it all out for me!
-Jedon

Quote from: mbryner on October 05, 2010, 01:23:23 AM
Hi Tom,

hee hee, we have exactly the same setup.   What kind of charge controller are you using?   Can it handle high voltage V(oc)?   I just drove through Hopland a few weeks ago.

I have a MX60 and it can handle 140vdc max. Which is just a smidgen short of what is needed, it sometimes blows the 60 amp breaker on a cool bright day when the batts are low. I'm still trying to decide what is the best way to charge the batteries given the equipment I have.

Our houses are very similar too. During construction of our house the st5 was wired for 120 vac with a 4 plug receptacle for power. I trained the contractors to fuel and run the genny. They picked it no problem. Are you in Hopland often? I work at home so let me know if we can meet.

Hello gang,

So, I finally have some real data for you to peruse.  I've slowed down the Listeroid to about 550 (?) rpm using a tiny key-ring in the governor mech (just lengthens the spring) for when it is in "120 volt DC charging mode."  (See my last post above.)  This makes the output voltage about 80 V DC after going through the bridge rectifier.   The large choke was essential.   Without it, the charge controller seems to "hunt".   It would load down the Listeroid with up to about 1500 watts, then drop the load immediately, and repeat.   With the filter choke, the MX80 charge controller pulls about a 1600 watt load and holds it well.  1600 seems to be the max because the voltage drops as the engine is loaded and rpms drop.   Every little while the charge controller lets off the load and (I assume) checks the battery status.   Perfect.   When it is drawing a load, the engine rpm's drop to about 480.   I'm just counting the exhausts puffs per min and multiplying by 2.   You'll notice I gave up recording the Hobbs meter, because at the lower rpms/voltage, it runs slower, too!

The engine seems to be quite efficient at this slow speed and load.  (Anyone know what the rated HP is at this speed? Are there any downsides to running the Listeroid this slow?)  The fuel efficiency compares very favorably to other published results on Utterpower.  Overall, I am very pleased!    Pictures will follow when I have a chance later tonight.

		Total Run	Fuel tank	Kwh	Total kwh		Hobbs
Start	0955		10 gal				201.3
	1925	9.5 hr	8 gal	16 kwh	16 kwh		209.0
End	2215	12.3 hr			19.8 kwh		211.1

		Total Run	Fuel tank	Kwh	Total kwh		Hobbs
Start	0755
	1505	19.47 hr	6 gal	11.3 kwh	31.1 kwh
End	2230	26.88 hr	~4.5 gal	11.6 kwh	42.7 kwh

Results at 6 gal mark (more precise):

Average charge rate:	31.1 kwh/19.47 hr =	1.60 kw
Average rpm: ~480
Fuel efficiency:	19.47 hrs/4 gal =	4.87 hrs/gal
		or 0.205 gal/hr
	31.1 kwh/4 gal =	7.76 kwh/gal
		or 0.129 gal/kwh

Results overall:

Average charge rate:	42.7 kwh/26.88 hr =	1.59 kw
Average rpm: ~480
Fuel efficiency:	26.88 hrs/5.5 gals =	4.89 hrs/gal
		or 0.205 gal/hrs
	42.7 kwh/5.5 gals =	7.76 kwh/gal
		or 0.129 gal/kwh

All measurements at ~1780 ft above sea level,
performed 10/24/2010 + 10/25/2010

That's very encouraging! Now that generator season has started for us I'm thinking real hard about converting my ST5 to DC also. I'm planning to pull wires for each pole and rectify the 60vac and feed that straight into a MX 60. Done this way I shouldn't need the choke and also should be able to get full rated power out of the engine. I'm thinking things could be switched between dc & ac with a 4 pole transfer switched although I haven't worked out the schematics yet.

The occasional shutdowns you are getting is when the charge controller re-sweeps the "Panels". You can set this value to a real high number to stop that as it is really not needed as the MPPT is always the same. My MX60 will also do a restart about every 30 min and that setting can be changed too. Do you feel that the MPPT function is correctly/effectively limiting the amps pulled from your system?

Hey guys, sounds like fun.
I would try the Outback's MPPT 'U-Pick VOC% mode' and change the percentage of VOC to find a setting that will load the generator to where you want. Since you are using a choke input filter you do have some source resistance but not quite like a solar panels more constant current output.

Maybe you could contact Midnight Solar about their new Classic controller. They have a high voltage model that might work well with rectified generator output. They say it will do everything else (even talk to you) ;) I think the controllers are almost out of vaporware!!!

Greg

Greg: Yes, the Midnight Solar charge controller would work great for this application, but it's expensive and I already have the MX80 for 3400 watts of solar.

Tom: 

1. You can't really adjust the sweep interval to a very high value if you are using the controller for solar panels, too. 
2.  In this very long thread we discussed using a 2:1 step down transformer to for taking 120 VAC to 60 VAC and rectifying, but the resultant voltage won't be adequate for equalization charging and you'll need a hefty transformer.
3.  I tried without the choke first, but the high ripple seemed to confuse it.   With the choke it works great.   
4.  You can make a simple breaker setup of 2 double pole breakers to switch between 120 VAC and 240 V AC modes.   I can post here the wiring schematic I figured out.
5.  I don't think the setup is limiting the amps pulled from the generator:  I'd need to find a power curve for a 6/1 but as the rpm's drop the HP drops pretty steeply IIRC.   3+ HP at 480 rpm is probably reasonable, so 1600 watts is appropriate.   Just guessing.   Overall, I'm overjoyed!   8)

Marcus

in my humble opinion, you likely have it optimized to about 95% of whatever outcome one could get
if he had an unlimited budget, basically getting the last 5% is going to progressively more expensive.

you are coming in right at about 8kw/hrs per gallon, which is very good considering most get right at that
amount out of a 6/1 at full output AC, considering the conversion steps you have added, it is apparent to me
that you have done very well indeed.

there are losses from the rectifiers , losses in the mx80 which together likely net a bit over 90%

so the engine bsfc factoring in those efficiencies, works out to be what?  .127 gal/kw/hr x 90% = .114 gal/kw/hr     

thats probably about right for a 6/1 driving a st head at that level of output and engine speed

actually thinking about it, the setup is likely doing much better than that, considering  a 6/1 will come no where
near .125gal/kw/hr with a load of 1600watts AC, it will likely come closer to .160 gal/kw/hr or more, i would have to check my
notes to see what the baseline is.

i do know the first kwatt generated is the most costly in fuel consumption, the second is better and the third kwatt is the cheapest.

so overall i would be well pleased too if i were you

bob g

bob g:  Thank you very much.  Your opinion is highly respected.

And here are the promised pics:

The bridge rectifier (100 Amp 100 V) and 120/240 ST head mode selector box:
(disregard the "left/right" written on the box, it was cannabalized from our temporary house construction power pole)

(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4189&g2_serialNumber=2)
(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4188&g2_serialNumber=1)



Old transformer (must be at least 75 lbs) used as inductor.   "+" DC with ripple from rectifier in one side of primary and "+" DC cleaner output to charge controller from other side of primary.
(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4191&g2_serialNumber=2) (http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4190&g2_serialNumber=1)



Opened up DC side of Outback panel and temporary placement of choke on the floor below.  Charge controller is on the right.   The plywood box is the battery box.
(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4193&g2_serialNumber=2) (http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4192&g2_serialNumber=1)



The day's data on the MX80 display:
(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4195&g2_serialNumber=2) (http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4194&g2_serialNumber=1)



Yes, I need to clean up the wiring at the ST head now that it's proven to work.
(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4197&g2_serialNumber=2) (http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4196&g2_serialNumber=1)



And my unique rpm limiter: a tiny key-ring from a Swiss Army knife was just the right size and makes switch over back to 650 rpm a trivial task.
(http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4199&g2_serialNumber=2) (http://listerenginegallery.com/main.php?g2_view=core.DownloadItem&g2_itemId=4198&g2_serialNumber=1)

There, a short tutorial on how to make a Outback MX80 or MX60 charge controller get DC current from a standard ST generator head....

Marcus
I'm glad to hear it's all working out. It's easy to see you've been a very busy man. The house and its location are incredible.

My setup has been working as well.
Recap
(ST5/120v-->240v to 208v transformer-->rectifier-->MX60-->48v battery bank)

The Metal Film Caps on the rectifier seem to have eliminated the MX60 display problems but I haven't been running it at high amperage either. I bought a 2500 watt inverter and power a few loads with it. The old UPS was just too inefficient.

Thanks, Geno

Awesome setup!!!!  Is the charge controller necessary, or could it be bypassed in favor of just connecting the outback (for a grid tie setup)?

Hi Geno,

I wondered how your's turned out.   You gave me the nerve to hook up rectified DC to the MX80 with your positive report (except the garbled display!).  So, your transformer takes the 120 v down to 104 V, making it safer for your MX60.   Good setup too.

Hey Brett,

You were the inspiration for this whole thing, when you separated the 4 poles of the generator into 60 V each.   Are you still using it?

Is the charge controller necessary for grid tie setup?   Don't know.   How would the inverters react to dirty DC?  Good question.   Anybody have a Sunnyboy inverter they want to use for this application?   Seems like very expensive backfeed to the grid, though, unless you get the fuel for free.   At farm diesel price of ~$2.80/gal, and generating at 7.76 kwh/gal, you're looking at $0.36/kwh.   Let's say you mix 75/25% WMO/diesel or WVO/diesel, and your WVO or WMO is free then your cost is $0.09/kwh.   Compare that to your power bill and see if the cost and hassle are worth it.

Great to hear from you both.

coordinate or schedule your genset run time to the time of day where you can use the waste heat to best effect
either heating domestic hot water or space heating in winter and your cost per kw/hr drops dramatically.

certainly well under the grid cost in most cases, most especially if you are living a very efficient lifestyle to start with
where all the addon costs on the electric bill raise the actual cost per kw/hr to in some cases twice the base rate, or more.

this is why i look to automation so heavily, it is my firm belief that i can remain very competitive with the power company rates
even burning 100% pump diesel year round

bob g

After getting the 60V output on the ST head, I kind of stalled on that aspect of things for awhile.  I'm currently in the middle of plumbing a FPHE inline with the engine coolant to an old cast iron radiator that will be mounted in my living room.

I just ordered one of the GVFX3648 inverters to try.  Although it can charge batteries, I want to see if I can connect it to the grid, and a DC imput and run my meter backwards.  The DC may be rectified from the ST, or from a large 48V DC power supply (3000W if I recall).

Does anyone know if the outback will work this way, or do I need to have batteries connected?

Ahhhh..... too many projects at once.  I'm sure no one here understands  ;)

Bob,

You were talking about paralleling all four poles into one bridge rectifier. Would it not perhaps be easier to run each pole into its own rectifier and then parallel the outputs of the rectifiers?

Bschwartz, I think you would want at least a small battery bank to smooth out your dc ripple. It would seem to make the inverters job really difficult to deal with fluctuating input while syncing to the grid. I am anxiously following your adventure as I plan to do a similar project except charging batteries. I would think that you could adjust the governor on your engine to keep the batteries around 54vdc and you would be good to go with the inverter.

Tom,  if it doesn't need the batteries, then the 3000 watt 48v DC power supply (I think I can crank the voltage up to about 54V) should just power it fine without any filters.  I think it was designed to power a computer setup of some kind.  The brand is KEPCO, rated at 48v 60A.  Inside of the box I think are two paralleled 30A units.  It won't be the most efficient with the conversion from 240v AC from the ST, to 48V DC in the power supply, back to 120V in the Outback, but losses while running on WVO, or WMO don't bother me.

It might not need the bats, I'd just hate to think of letting the magic smoke out of a $2k inverter. I was thinking of a small battery bank, say 4 70 ah marine/deep cycle units. I don't think you would loose much if anything efficiency wise since the batteries would just be a buffer.

i would not run the rectified dc from an st head directly into an inverter without the use of a battery buffer

my exeltech mx series system will take from 42 to 62 volts input (48volt nominal) but anything over 62 will cause a fault and drop out
and then takes a manual reset.

i would imagine any quality sine wave inverter will operate on the same principle,

when it comes to rectified power from something like an st head, without some form of regulation that is very fast
when there is a load dump the dc voltage will spike much higher than 60 volts which will cause the inverter to trip out, hopefully...

or worst case, damage the inverter.

a battery bank is very good at being a buffer and clamping for the most part when load dump occurs, and also has the ability to
provide a boost for starting heavy loads, depending on inverter capacity the 3kwatt limit of a 6/1 could become two, three or more times that limit for several seconds or minutes if need be.

lots to be said for including a battery buffer

if all the batteries are asked to do is provide a buffer and/or a momentary boost, i would look toward using standard automotive starting batteries, they are made to deliver massive amounts of current for several seconds, recharge more quickly than do deep cycle
and are cheaper because of economies of scale, probably a million car batteries are built for every one deep cycle battery.

fwiw

bob g

Bob,  I wouldn't go from the ST head to the Outback inverter directly.  Do you think the Outback would be OK taking its 48v DC from a 48v power supply that is powered from the ST head?
I'd think with a static load of just the power supply on it, the 6/1 with ST head should be stable enough to provide a constant 240v AC for the power supply which would in turn provide a stable DC voltage for the Outback.

Am I making any sense?
Maybe another cup of coffee.........

I guess 4 car batteries would be cheap insurance though.

I was also lucky.  Instead of it being a $2000 inverter, I found a factory refurb for $1161 !!!  So the magic smoke would be ...... nevermind still too much to imagine :)

Update:

This morning I installed a 10 ohm Ohmite rheostat to the excitation loop in the ST 7.5.   Using the full 10 ohms brings the output voltage to ~93 VAC instead of ~115 VAC.   The DC output from the rectifier/choke combo is now in the 120-130 volt DC range.   Hard to measure precisely because as soon as I flip the breaker, the solar charge controller locks on and starts charging at ~2500 watts.   Perfect!!!  

The only problem: the toroid transformers I'm using are getting quite hot still, even though I'm running at full 650 rpm (60 Hz) now.   I'll need to find a real 5 kw 2:1 transformer.   The only real reason for the transformer is isolation of the circuit to allow for common ground between the generator and DC neg.   I can produce power via the 120 V gen head setup, but the toroids take the voltage from 240 to 120 on the standard gen config.   Is there such a thing as just a isolation transformer with a 1:1 winding ratio?   Time to do some google searches.   I'll post pics later tonight.

Also, I'll start a new thread later tonight with data on how my masonry stove is heating the 500 gallon water tank in the basement.   You'll be waiting with baited breath for sure.....

Great news! What's the input voltage reported by the charge controller.

Quote from: mbryner on December 30, 2010, 01:08:10 PM
Update:

Is there such a thing as just a isolation transformer with a 1:1 winding ratio?   Time to do some google searches.   I'll post pics later tonight.

Also, I'll start a new thread later tonight with data on how my masonry stove is heating the 500 gallon water tank in the basement.   You'll be waiting with baited breath for sure.....

1:1 isolation transformers are common.  My pet pun name for such a beast is an "insulation transformer".  :D

You have a 500 gallon water heat storage tank in your basement?!  Sweet.

Quote from: mbryner on December 30, 2010, 01:08:10 PM
Also, I'll start a new thread later tonight with data on how my masonry stove is heating the 500 gallon water tank in the basement.   You'll be waiting with baited breath for sure.....

Oh baby!  Do you have a 1" stainless pipe in the flue passages ?

mike and rcavictim, I started a new thread for the masonry stove hot water system.    ;D ;D  Here it is:

http://www.microcogen.info/index.php?topic=1555.0

It is a stainless steel 1" pipe, but it's in the firebox, not in the flue.

Quote from: mbryner on January 05, 2011, 01:38:09 PM

It is a stainless steel 1" pipe, but it's in the firebox, not in the flue.

We got sssssssssssssssssssssssssssssteam heat, we got sssssssssssssssssssssssssssssteam heat......

I have a similar setup and the vfx3524 does support the listeroid.   Say a compressor comes on when I'm running a mill and someone in the house causes the well pump to turn on.  There might be a little blimp but it's nothing that would reset a pc. I'd be more pleased if it were so perfect that I couldn't even detect it in the momentary light flicker. But that's asking a lot.
   I want to clarify. Maybe we are talking about the same thing.  It is not really supporting the generator.  It is replacing the gen ac with inverted ac until the excessive load passes then it returns to generated ac.  But I'm pleased with that.

Quote from: Tom on October 04, 2010, 09:11:53 PM
Marcus,

Welcome to my world. We've got a 3.4 kw solar array on the roof and s listeroid 6/1 too. Ours was used without the solar panels for 99% of the construction because we mounted the array on the roof. The system is currently setup to charge through the out back vfx3648 inverters that are wired out of phase to feed a standard utility panel. The only real problem we encounter is that if the micro wave or jet pump turn while the generator is running it will lower the voltage enough to cause the inverters to drop out of charge mode and then in a minute they will reconnect. I had expected the inverters to come with "Generator Support" however although the menu item is there it is not functional. Had the generator support  been functional when the load exceeded the max amp set point the inverters should have synced to the generator and switched to inverter mode until the load dropped and the inverters would return to charger mode.

I have contacted Outback about this without reply and am quite disappointed in how they have handled this. I've even wrote a correction to Home Power magazine about their article stating that the Outback inverters will do generator support and no reply from them either.

So assuming you have outback inverters you are stuck as am I. Please keep us informed as I am thinking of doing something similar to you with our system.

Hello Billk,

Yes, we are talking about the same thing.   My vfx3648's  will not work like your Outback inverter does, that is, supply battery power instead of charging until the excessive load passes.  That's what made me start this thread.

This thread is fairly old and I've made several changes to my system (that are one other threads) but the overall concept is the same.   The first setup as described here was ST head 240 VAC --> 2:1 isolation transformer --> large bridge rectifier --> filter/choke --> DC input to MX80.   The Outback charge controller (MX80) couldn't handle the higher voltage from the 120 VAC rectified to 160+ VDC.   Therefore, I had to use a 10 ohm variable resistor in the excitation field to decrease the output to about 90 VAC.   Then, the ST head didn't always self excite correctly, though.   It was a pain to fiddle with the variable resistor and breakers whenever I went to Lister charging mode.   Also, you have to limit the charge current somehow, which can be done in the MX80 but then you won't be using all your solar potential.    So, I bought a Midnight Solar Classic 200 which can handle higher input voltages than the Outback.   I was able to eliminate the variable resistor from the circuit and I don't have to go through menus on the charge controller every time I do Lister charging.   The Midnight Solar Classic is also used for my new hydroelectric input, so I needed it anyway.    That brings this thread up to date, and hopefully answers your PM, also.   The system works great as a giant UPS now!

Marcus

Hello Billk,

Welcome to the forum! It sounds like your inverter has a functioning generator support system, I know some of the foreign ones do. Unfortunately Marcus and my Outback inverters do not have that feature working. It is a menu item, but non-functional. So when the big loads come on there is no assist from the battery.

I just looked at the sticker on my first vfx3524. It was made 4th quarter if 2004.  I think I got it a month after that. that's the one I used with successful support. Just last month I installed a second  vfx as a dedicated charger.I do not know if it supports.  It was only temporary. It's going to be used for its intended purpose after I install a charger.  And this thread has found it for me.   I'll be installing a midnight classic this week or next.
  So what happens when your inverter fails to support? Everything goes black and then comes back on 30 seconds later?
  Curious thing, the new vfx that I have been using as a charger is made in India unlike the old one and when the fan comes on it smelled exactly like aspirin.  And a lot. Like if you held your nose to a bottle of it.  Only your 3 feet from the inverter.  I have never smelled that from an electronic device. That did go away after a while.

Quote from: Tom on August 16, 2012, 10:53:32 AM
Hello Billk,

Welcome to the forum! It sounds like your inverter has a functioning generator support system, I know some of the foreign ones do. Unfortunately Marcus and my Outback inverters do not have that feature working. It is a menu item, but non-functional. So when the big loads come on there is no assist from the battery.

I could be wrong, it's been so long since I got the vfx, it was 2005. But I think I had problems with the generator support.  Its just possible that I had to send back my outback mate and get another one sent to me. Like its  1st gen EPROM had old or buggy code that didn't work with that feature.

I have worked with some of the top engineers at Outback, the generator support is not and will not ever be available in the VFX3648. The manual that came with the unit confirms that generator support is not enabled on my unit.

I need to add another charge controller to my setup so I can add the extra solar I already have.  I have every part to do as Marcus is doing except the controller.  I currently have an MX60.  Instead of getting another MX60 I think I will go with Midnite and get the classic 200 just for this purpose.  I am in the process of setting up a 110-555 for charging.  But if something happens to that it would be nice to use the ST5 (or other 240vac source) and Classic 200 as a back up.  Thanks for updating us Marcus!