Micro CoGen.

Bob,

Now you've got me thinking.  You are right about the diodes getting close to their avalanch point.

If I were to go to an external 3-phase rectifier, I could kil two birds with one stone.  I could avoid the voltage drop by running the AC outputs from the 555 to the inverter rack and mount the external rectifier at that point.

Any recommendations as to an appropriate kit (with heatsink)?  I'm placing my orders before my annual home leave coming up in two months.  I'm certainly not going to find anything like that here.

I've found a 6 1/2 pulley.  The flywheel is down at the machine shop now, and we are figuring out the best way to mount it this weekend.

Cheers..

Outside Kampala, Uganda.  Right on the shores of Lake Victoria

(cont)

The battery sense cable had a voltage drop of 0.25v.  V at the bank was 12.79, v at the Sterling was 12.55.  This held pretty stable for the 20 minutes I ran the test.  And it's about what I expected.

My goal with this setup is to get the majority of the bulk charge out of the way by mid-morning.  Then, even in the rainy days, I can reach full absorb at least once a week. Since I have to replace about 150Ah during a partial day, and to conserve fuel, I was hoping to recharge the bank in about 2 or 3 hours.  Hence my needs are to generate between 50 and 80 amps from the genset.

Obviously, I'm spinning the 555 too slow.  Fortunately, there are good (relative...) machine shops around here, run by Indians.  Their daily wage is about $10, so to do the flywheel mods would not be that expensive (there are advantages to living in the third world).

I was considering running the ribbed belt around the circumference of the flywheel, but: my 175 has a 13" diameter flywheel; my 555 pulley is 3".  That would spin the 555 at around 8,000 rpm, which is too close to max for my comfort (the Change-Fa maxes at 2300 rpm).

As to the intermediate shaft: I haven't discarded it completely, but as Steve points out, it's an additional loss on a 6HP engine.Plus I have to wait until my stateside visit this summer to get the pillow block and pulleys, and new belts.

That leaves me at presen with trying to fit a 6 or 7" pulley onto the Change-Fa.

I'll visit the local machine shop in the next few days to see what they can offer.  I can get the larger pulleys from the CHinese dealers (for the larger engines), but of course they don't fit the 3-legged bolt pattern of the 175 flywheel.

I think after this is done, it would be worth a write-up as a white paper ala 'Driving automotive alternators with Chang-Fa's'.  I suspect most of the members wanting or doing this setup will be running 24v/48v systems, and will need to up their drive speed.

Again, thanks for the help so far.

Pete

 AL, Steve, Bob

Thanks for the info and input.

Bit of background: I started all of this after ditching my 15kva 3p genset.  I live off-grid, even though I'm ouside Kampala, Uganda.  I live right next to Lake Victoria (at 3800' altitude).  I've got an Outback setup with an 800Ah battery bank and 4Kva PV array.  My batterys are tubular FLA from India.  My usage is appx 150AH per night (20% DoD).  During most of the year, the sun is great, as I'm about 30 seconds north of the equator.  The only time I use a genset is during the rainy (monsoon) season.  I live on rainwater, and to give an idea of our rains, I collect between 1 and 1.5 thousand litres a night from 1/4 of my roof.  My system is set so that the absorb voltage on the battery bank is 29.1v; the float is 28.0  During the dry seasons, I reach float by noon most days.  My biggest draw on the battery bank is a 400 watt water pump in my aquaponics setup. That runs from about 9am to 6pm.

I was motivated by Bob's white paper, as it seemed a much more efficient way to charge than the conventional AC gense, consideringthe max charge current I can get out of Outback inverter is about 60amps.

After hunting around in the states for a 555, I went to Eric at Romain Electric in Tacoma, Wa.  He got me an original Leece-Nevile 160A JHO. He special ordered the bi-directional fan. He went above and beyond to get this shipped to me before I left the states.Hightly recommend him.

I got the Chang-Fa from a fishing canoein exchange for an Yamaha outboard.

I had heard some quality issues with the Balmar regulators, so I decided to go with the digital Sterling kit. 

I then followed Bob's white paper.  The only real change neccesary to connect the Sterling PDAR was to hook the high voltage sense line to the voltage sense line, rather than to the alternator B+ terminal.  The voltage sense lines are run from the Sterling to the battery bank with a 1.5mm x 6m dual pair wire.  The main battery cables are 4 gauge battery cables from the states, connecting to the genset with an Anderson 100A connector.  I brought the main cable from the states, as it is just not possible to get decent large gauge wire here.

I ran some more tests this morning.  Here's the results:

Starting voltage for the battery bank: 25.3  The sump pump for the aquaponics setup was running, hence the low reading.  Warmed up the Chang-Fa for 15 minutes.

The Sterling did the low-amp startup for a few minutes.  The current to the battery bank started at 40A (as measuredby my Flexnet); then settled to 25A.

There was a voltage drop of 0.8v on the main battery harness.  V at the alternator terminals was 26.95; that at the shunt was26.17

)Veggie,

Sorry  to jum topic here, but since you have the same 175/555 combo I've got, what combination of pulleys are you running?  I've got 4" on the engine and 3" on the alternator, and am spinning the 555 too slowly (engine at about 2300 RPM).  The 555 is running at about 3000 rpm, and it should be about 4500 to 5000.

Pete

Ok, I think I have the problem.

I'm using the 555 re-purposed to charge a 24v battery bank.  I need to be spinning it at about 5,000 rpm for it to put out the amperage I'm expecting.

Since I can't find a bolt-on pulley, I'm probably going to be forced to go with an intermediate shaft and set of pulleys.

I just checked the output curve again in the spec sheet.  At 3,000 rpm, I should be in the 120-130A potential range.

Steve,

It's got the bi-directional fan on it.  I am spinning it counter-clockwise, but according to Eric at Romaine Electric (where i got the alternator), that should not be a problem.

I don't know how to get the alternator to spin any faster.  The only pulleys I can get for this are the stock ones, at appx. 3" diameter.  The Chinese dealer here says there are no other pulleys available for the 175 engine.

The stock pulley on the engine is 4"; the 555 is 3", so I figure I'm spinning the alternator at about 3,000 rpm.  I would like it to be spinning at 5,000, but that's not going to happen with this setup.

Do I need to start thining about an intermediate pilow block/pulley setup?

Pete

ALright, I've been running more tests this week, and i'm not satisfied with the results.

I cannot get this baby to put out more than 40 amps.

The Sterling regulator appears to be working fine.  I've put a meter between the field supply battery and the field (on the negative side; I've got the alt/controller wired for positive side control).  I am pulling a pretty constant 4 amps into the field. The regulator starts off in it's initial 'reduce belt slippage' mode, then switches to full power mode.

The engine is spinning at about 2300 rpm (as measured with my optical tach).  The coolant is boiling; the alternator is getting plenty hot.  I've got 20 feet of 4 guage wire connecting the alternator to the battery bank, and i't not overheating.

Using my flexnet DC on my Outback setup, I'm getting 41a max initial output. After a bit, it settles down to between 25 and 32 amps.  The battery bank has had 180Ah removed from it, so it's sitting at a bit above 80% SoC.  The charging voltage looks correct at appx. 27.5v.

I'm wondering if belt slippage could be my problem.  The 'A' series belts are not seated fully in the Change Fa pulley, as they are 'B' profile.  Unfortunately, when I received my new 'B' series pulleyhere, it was actually an 'A' series, so I'm stuck with it for a while.

Any ideas?

Bruce,

I've tried many custome circuits and devices for a LVD.

The two best ones I've found are:
1- Battery saver for 12v coolers.
2- Stecca 5 or 10A charge controllers

My biggest beef with them is that they set the LVD at 10.5 volts (under load), which I think is too low.  But they are reliable.  They both let the battery come back to about 11v before reconnecting.  The cooler saver is about $25 in the states (I think I got the last one from Amazon).   The Stecca's are about $25 to $40 here in Uganda; should be about the same in the US.

As to hooking it up:

The diagrams show inserting it in series with both positive and negative leads.  One side of the meter is for connection to the source; the other side is for connection to the load(as in PV:Battery or Battery: Motor0

What I've found is that only the negative lead needs to be in series.  Either of the positive leads can be connected to the B+

I don't belive the 130A rating is anywhere near sanity.   But I use it regularly at 30A, and no troubles.

If you want higher ratings, crack the case and bypass the internal shunt with one more appropriate to your needs.  Google some of the EV forums and you'll find photos and instructions

For that price, getting the logging features alone is an incredible bargain.  It costs well over $100 to do the same with an Arduino fitted with current measurement, data logging (SD card), and display shields.

These are essentially Chinese clones of the Watts-Up meters, at one-half the price.

As to their quality: I have over 100 of them in use metering pico-grid projects in Africa, and only one failure in more than a year.  Try to find a way to meter 24v DC to a rural African home where the average monthly bill is $3.

Pete

I've spent years playing with battery monitors. 

My favorite (esp. if you want a serial interface to pull data off with) is the Outback Mate (old style) combined with the FlexNet monitor.  However, those are some big bucks.

If you want something affordable, check out the Tunigy 130A meters.  The a multi parameter reporting device, made for model airplance use.  But they read up to 130 ampsDC.  They report instant, peak and cumulative volts/amps/wattts on the readout.  No data interface though.

http://www.hobbyking.com/hobbyking/store/uh_viewItem.asp?idProduct=10080

They are unidirectional, so i use one for the load side and one for the charge side. Simple math to figure out your real battery level. A 3 pin header allows you to reset the counters.

I've been using them for about two years on solar installs and my sailboat (one for each charge source: alternator, solar, wind)

Best part: $23.

Pete

I have to say I've been very happy with the Sterling regulator. I'm using the PDAR with the 555, and I'm very satisfied with the results.  A lot cheaper than the Balmar.

As to the current sensor, have you seen the Pololu 30A sensor ( http://www.hacktronics.com/Sensors/Current-Sensor-30-Amp/flypage.tpl.html ?  It may be too small for your application, but they work very well with Arduino's and other pico-boards.

Pete

Thanks for that double check.  i wanted to do that before I left Africa, but could not find a 'b' series belt.  I was told by the Chinese agent that I could not use auto belts with the pulley, but that I had to use agrocultural belts.

I guess that's the difference between the 'A' and 'B'

Just to hedge my bets, I ordered both 'AX and BX notched belts, and a common back BX belt to take back with me.