off grid delima 48v system

[rosscat3]

I have been happily living off grid for 7 years now. My system consisted of a 1250 ah battery bank. a trace 4048 inverter. solar array ,1500w other power desighn wind generator.a 905 kobota diesel engine with adirect copled 10kw genset this system has worked  very well for 7 years .Untill last weekend  I went to install a new battery bank I had uwittingly installed the solar and wind generator on the wrong side of my battery disconect feeding all that power back in to my inverter (very bad) anyway I have  another inverter an st-2500-148 .And then it hit me all this time I had been charging my batterys with my inverter now I have no way to charge batteries.We still have the generator for lights and everything else so we are not in the dark,what a bad time of the year for this to happen. All this lead me to completly re think my whole system had I incorperated a battery dedicated charging system with a smaller diesel motor it probably would have been more efficient, and kept the larger generator for large loads and 3 phase, we would'nt have the problem I have now.
  I have been reading on this forum on two main topics charging a battery bank with a converted as per bobs white pages or converting an ST
So this leads me to my question

  There is a  2 cylinder yanmar diesel coupled to a St 3 phase 8000 kw genset that i could buy for $600.00 to modify by isolating the coils ( i think the motor is too small )  or I have a large frame alternator by power technologys model # 960501714 that is externally regulated that the data plate reads( its hard to read ) 120 volts, 27 amps 3 phase that I think would be easy to convert with a bridge rectifier
any help would be appreciated on which might be the best alternative.

This fourm is great a lot of very well informed group of people

[mobile_bob]

another alternative might be to buy a used 48volt battery charger, like one used on golf carts
that at least could be simply plugged into your genset to keep the batteries charged. not the most efficient but
it would be most effective in protecting your battery investment till you get some thing else sorted out.

and it could then be used as a backup charging source later.

a 1200amp hour bank is not cheap by any means, so you probably ought to do whatever you can asap to assure that
the bank is maintained properly (charged), and yesterday probably was not too soon to have done so.

just my opinion of course.

the yanmar with 8kw head for 600bucks sounds like a good deal, and maybe it could be modified to do what you want
actually i know you can do just about anything with a bit of research and testing, given enough time and money.
setting it up with a 3phase rectifier bridge and then taking control of the field so that you can regulate the charge current and voltage
would make it a nice charger i would think.

bob g

[LowGear]

I read this kind of fast and most folks know I'm really out of my depths with your problem but Simple is sometimes a good answer:

a trace 4048 inverter

As in just buy another one.  Hook up all the wires and whistle while you design and put together the ultimate, incredible, perfectly designed system.

Casey

[rosscat3]

another alternative might be to buy a used 48volt battery charger, like one used on golf carts
that at least could be simply plugged into your genset to keep the batteries charged. not the most efficient but
it would be most effective in protecting your battery investment till you get some thing else sorted out.

and it could then be used as a backup charging source later.

a 1200amp hour bank is not cheap by any means, so you probably ought to do whatever you can asap to assure that
the bank is maintained properly (charged), and yesterday probably was not too soon to have done so.

just my opinion of course.

the yanmar with 8kw head for 600bucks sounds like a good deal, and maybe it could be modified to do what you want
actually i know you can do just about anything with a bit of research and testing, given enough time and money.
setting it up with a 3phase rectifier bridge and then taking control of the field so that you can regulate the charge current and voltage
would make it a nice charger i would think.

bob g

Thanks for your response Bob I am very much  interested in retrofitting the ST would the procedure be the same as what you outlined in a previous post or is there a difference in the 3 phase units layout?

[NevadaBlue]

I think I'm lost. You mentioned 'solar array'. PV panels? Why won't they charge the batteries?
I'm running a pair of 4048s and I use my panels for charging when the sun is shining. What am I missing?

I agree with getting another 48 volt inverter/charger, but...

[rosscat3]

I think I'm lost. You mentioned 'solar array'. PV panels? Why won't they charge the batteries?
I'm running a pair of 4048s and I use my panels for charging when the sun is shining. What am I missing?

I agree with getting another 48 volt inverter/charger, but...

Well I live in the pacific NW so the solar panels only trickle charge right now.The wind generator is keeping the inverter going part of the day but my battery bank is so large the wind could blow 30mph 3 days straight and still not top off the batteries.

[rcavictim]

I am facing a sililar dilema.  I have a 1200 AH @ 48 volt battery bank which will feed my 10 kVA inverter.  To charge the battery bank  I need something like a forklift battery charger that can push 200 or more amps into the batteries in bulk charge off nice civilized 60 Hz, 3-phase diesel genset power. That's pretty straight forward except for the multi-step charge contoller part which I need to come up with.  More of a challenge is that I also need to be able to provide charging when the voltage is wild and the frequency drops to even less than 15 Hz without saturating the xfmer core in my charger.  That means I need a much larger xfmer.

Over the weekend I lucked across an auction for a big power 35 kVA welder on the internet.  It is a multi voltage 230/460/575 volt 3-phase transformer and a current control and rectifiers good to about 600 amps DC output.  Pic attached.  I actually won bidding on two identical of these complete units!  Can never have enough spare parts!  I need to pick them up this week.  They are 2-1/2 hours's drive away one way.  I got them cheap enough that the transport costs added still leave me with a good deal.  Man these are gonna be heavy.

Building a battery charger out of one of these seems to be the cheapest route I can come up with for a charging system.

[mbryner]

Hi Rosscat3,

Welcome!   Tell us a little more about yourself if you want.   There are actually quite a few of us here in the NW.   

We're just about to move into our off-grid house and I have a 5600 AH battery bank.   Our 3 kw of solar panels are only producing ~100-200 watts in this rainy weather.   Not nearly enough to keep up, same as you.   If you've gone back through previous threads, you'll find I've been experimenting with a rectifying single phase from an ST and feeding that into a Outback solar charge controller for better charging than what the inverters do.   So far, the main troubles have been either overloading the Listeroid or not drawing enough.   Like Mobile_bob said, adjusting the field current in the ST may fix that.   

The advantage of rectifying 3 phase will be much less ripple to try to smooth out.

mobile_bob:  you mention golf cart battery chargers.   I thought of those, but they only put out 10-15 A.   That may work great for Rosscat3, though.   I would be charging for a *long* time at that rate, not to mention 'roid inefficiency.   I guess one could parallel 4-5 of them together if you found a good deal.

rcavictim:  a welder sounds like a great idea as a base for a charger! 

Marcus

[Apogee]

You guys might consider finding single phase 240V forklift chargers.

I used to run a large distribution center and we could fully recharge a dead lift truck in a few hours.  If memory serves, our lift trucks had 1450 amp/hour packs in them. I remember they cost ~$6K to replace and weighed a ton (literally).  The chargers have equalization and conditioning cycles built in.  Keep in mind that forklift battery packs get run down every day sometimes multiple times if running more than one shift.  As a result, the forklift manufacturers have had to really develop their chargers to allow the batteries to have a decent service life.

I just looked on the Crown website and pulled their battery accessories brochure to verify.  On page 6.22, the chart shows their 48 volt chargers put out between 750 and 1050 amps per hour.

The chargers have selectable input voltages and *I think* they also offer single phase versions (or perhaps the same unit does both).  I know they're made even if Crown doesn't offer them.

I would suggest that all of you off-grid guys check out their catalog as it's full of handy stuff for the battery department.  You can order any of this stuff through your local Crown forklift dealer.

http://www.crown.com/usa/parts/pdfs/section6.pdf

Enjoy and Happy Holidays,

Steve

[rcavictim]

I agree with Apogee about looking for a forklift charger.  I was headed in that direction when the welder suddenly diverted my attention.  Trouble with my particular application is the wild and very low frequency operation I needed because of the wind turbine input.   That put a big monkey wrench into what kind of forklift charger would work.  If your source of recharging power is a constant 50 to 60 Hz or so you should be hunky dory with a forklift charger.  Yes they (the recent offerings at least) have the desireable multi step charging program to maximize battery utility and life.

[mobile_bob]

to be honest with you, i don't know why i mentioned a golf cart charger, even though it would be better than no charger
they are really too small for any decent size battery bank.

in the back of my mind i was picturing the much larger forklift chargers, you can find them sometimes at industrial surplus yards
such as what used to be boeing surplus,,, rip

i remember them always having one or two of the one ton cube chargers and usually wanting a couple hundred for one.

the only problem i see with using one, is just like the battery

big horse eat lots of oats!

750amps at 57.6 volts (charging voltage for 48volt nominal) = ~43kwatt, not accounting for efficiency losses, so i would expect
to get the full 750amps you might need to drive it with a 50kwatt genset.

and that even larger if the charger is an older unit with a poor power factor.

big battery banks take insane amounts of power to maintain them, especially if the bank ever gets sucked down very deeply
which is not hard to do in the winter months in the pac nw

as most folks also know, a battery that is allowed to sit at a partial charge, will soon have its normal soft sulfation begin to harden
and form hard crystals, this complicates matters and will then require even larger amounts of run time at elevated voltage to get the battery back
up in shape.

bob g

[mbryner]

750amps at 57.6 volts (charging voltage for 48volt nominal) = ~43kwatt

Over 10x what my 6/1 can produce!!! 

[rosscat3]

Hi Rosscat3,

Welcome!   Tell us a little more about yourself if you want.   There are actually quite a few of us here in the NW.   

We're just about to move into our off-grid house and I have a 5600 AH battery bank.   Our 3 kw of solar panels are only producing ~100-200 watts in this rainy weather.   Not nearly enough to keep up, same as you.   If you've gone back through previous threads, you'll find I've been experimenting with a rectifying single phase from an ST and feeding that into a Outback solar charge controller for better charging than what the inverters do.   So far, the main troubles have been either overloading the Listeroid or not drawing enough.   Like Mobile_bob said, adjusting the field current in the ST may fix that.   

The advantage of rectifying 3 phase will be much less ripple to try to smooth out.

mobile_bob:  you mention golf cart battery chargers.   I thought of those, but they only put out 10-15 A.   That may work great for Rosscat3, though.   I would be charging for a *long* time at that rate, not to mention 'roid inefficiency.   I guess one could parallel 4-5 of them together if you found a good deal.

rcavictim:  a welder sounds like a great idea as a base for a charger! 

Marcus

HI Marcus I have been following your threads on rectifying your  ST head .The problem with that thread is it is so long it is hard to get a definitive answer on wish way is the most efficient and the outcome of the different tests . As you are we are looking for a long term solution not a quick fix, efficiency is a main concern when your buying diesel as a prime mover energy source .  I was amazed when I seen that there were so many people from the north west on this forum.We have property on the beautiful Humptulips river in Copailis Crossing north of Aberdeen Washington.
    We have been off the Grid for over 7 years now my system up until recently consisted of a Kobota 905 3cyl diesel with a 10 kw 12 pole head it had provided amazing fuel economy of about less than a quart an hr  fuel consumption.That WAS followed buy a Trace 4048 inverter that has worked great for years (sure wish I could find someone to trouble shoot it) I guess I Should mention that the generator sets in a cinder block enclosure that is 8'x10'x7'h  8" cinder block filled with sand for a sound enclosure that sets in the corner inside my shop.Inside the enclosure I have 2 runs of 2" pipe and one run of 3" pipe all witch run out side to a 250 gallon tank 2" pipes are engine cooling, the 3" pipe is exhaust it also goes through the tank to heat the water, then I use the water to heat my shop.
   The wind generator is a 10' Arel flux generator built by Dan at Otherpower ,I have six solar panels that on a sunny day makes about 400w
(a waste of good money as far as I am concerned in this area)I had a flexcharge charge controller for the panels and wind generator but my batt bank is so large that a controller is really not needed ( you cant put too many amps in these batteries) at least so far.
   Well I bought the ST 7.5 3 phase generator and the yanmar 2 cyl  horizontal diesel what a buy the two coupled together for $500.00 now I am going to take the ST apart.I assume that the 3 phase armature is a 6 pole do I need to follow the same directions as outlined in previous posts by mobile bob using the four pole armature or am I missing something .I like the idea of three phases of 60 volts rectified to DC am I correct in thinking that  7.5 KW ^ 60 V = 125 Amps ?  If I have enough HP from my prime mover How much LOSS can I expect? Can I adjust my RPMs to compensate for this loss? What would be the best charge controller to utilize in this application ? Again my goal is longevity and efficiency. Thanks in advance Don C  
     

[rosscat3]

HI Marcus I have been following your threads on rectifying your  ST head .The problem with that thread is it is so long it is hard to get a definitive answer on wish way is the most efficient and the outcome of the different tests . As you are we are looking for a long term solution not a quick fix, efficiency is a main concern when your buying diesel as a prime mover energy source .  I was amazed when I seen that there were so many people from the north west on this forum.We have property on the beautiful Humptulips river in Copailis Crossing north of Aberdeen Washington.
     We have been off the Grid for over 7 years now my system up until recently consisted of a Kobota 905 3cyl diesel with a 10 kw 12 pole head it had provided amazing fuel economy of about less than a quart an hr  fuel consumption.That WAS followed buy a Trace 4048 inverter that has worked great for years (sure wish I could find someone to trouble shoot it) I guess I Should mention that the generator sets in a cinder block enclosure that is 8'x10'x7'h  8" cinder block filled with sand for a sound enclosure that sets in the corner inside my shop.Inside the enclosure I have 2 runs of 2" pipe and one run of 3" pipe all witch run out side to a 250 gallon tank 2" pipes are engine cooling, the 3" pipe is exhaust it also goes through the tank to heat the water, then I use the water to heat my shop.
    The wind generator is a 10' Arel flux generator built by Dan at Otherpower ,I have six solar panels that on a sunny day makes about 400w
(a waste of good money as far as I am concerned in this area)I had a flexcharge charge controller for the panels and wind generator but my batt bank is so large that a controller is really not needed ( you cant put too many amps in these batteries) at least so far.
    Well I bought the ST 7.5 3 phase generator and the yanmar 2 cyl  horizontal diesel what a buy the two coupled together for $500.00 now I am going to take the ST apart.I assume that the 3 phase armature is a 6 pole do I need to follow the same directions as outlined in previous posts by mobile bob using the four pole armature or am I missing something .I like the idea of three phases of 60 volts rectified to DC am I correct in thinking that  7.5 KW ^ 60 V = 125 Amps ?  If I have enough HP from my prime mover How much LOSS can I expect? Can I adjust my RPMs to compensate for this loss? What would be the best charge controller to utilize in this application ? Again my goal is longevity and efficiency. Thanks in advance Don C 
         

Report to moderator

[rosscat3]

Ok I did some more reading in (48v charging via an ST generator) and realized it is the stater that needs to be reconfigured . Do I need to ask these questions on another forum topic? I am new at using forums if I need to re direct let me know

Thanks Don C