Disparate Battery Banks

[Jedon]

Right now I have 16 used Trojan L-16's hooked to two Xantrex 5548 inverters. I have sitting around more batteries that I would like to use, 10 12V AGM from an industrial

UPS, and 7 6V Golf Cart batteries ( I could get one more to bring it up to 48V ).

Can I or should I hook these up to my system? Right now I'm charging off a 6500W gas generator and would like to minimize my gas usage until I have time to get my Listeroid 6/1 up and running.

Also, my L-16's never seem to show as fully charged even after doing an equalize and them going to float, I come back after an hour to let them settle and they are at around 48.2V which the Xantex manual says is about a 70% charge.

Thanks!

-Jedon

http://picasaweb.google.com/jedon13

[bob g]

something ain't right with the L16's

48.2 can't be 70% soc

more like nearly dead, so maybe your gauge is off?

as for adding in the golf cart batteries and the agm's

i wouldn't attempt it unless they were seperate banks to switch the

inverter to.

sounds like you got other issues to resolve first, before adding in batteries

bob g

[thirteen]

as an idea have you checked each battery by it's self you might have a bad cell or two. Just an idea

[Flux]

I also think you have dead cells in your bank, you say they are used batteries so that wouldn't surprise me.

Don't attempt to mix batteries in a string. You can parallel mixed strings without too much problem but each string must contain identical batteries or you will have to baby sit them constantly and do individual equalising ( if you know what you are doing).

Flux

[Jedon]

Thanks guys.

I think I meant 48.8 not 48.2 but in any case they never get anywhere near 100%. If I do have some bad cells what do I do? I have a specific gravity tester so I'll give that a whirl. Right now I can't charge over around 22A at 120V since that's all my generator can do off one socket, I could make a 220 plug and feed each leg to a different inverter to get more juice if needed, is it?

[zeusmorg]

I'd read the battery FAQ

[Jedon]

Again :-) I do read it every 6 months or so but I'm thick headed.

[bob g]

if it were me...

i would get a decent hydrometer one of the temp compensated ones

draw up a chart listing each and every cell in every battery

and take specific gravity readings and chart each cell after they have

been fully charged (or what you think is fully charged)

they should top out at about 1.260-1.270 although some manufactures run higher

to get higher amp/hr capacity out of a smaller battery by sacrificing lifespan.

whatever the case, you will likely find a few cells lagging behind.

take the offending batteries out of the string and independantly equalize them

at whatever voltage the manufacture suggests,, it might be 15vdc or higher, at very low amps,, and the battery will boil, it will get warm (not hot, if it gets hot, let it cool and then hit her again) keep after it until the specific gravity doesn't rise anymore for an hour.

then let it sit and cool for 24hours and retest the spec gravity

if it is off by more than .005 the battery has problems and will likely get out of

whack soon again causing more problems.

i am thinking that the string should be at or above 50.8 volts at rest after 24 hours, at 77 degree's F and be fully charged.

48volts and they are likely down to about the last 20% of remaining capacity, in which case it will take forever to recharge unless you got some good charger capacity, even then i would expect many hours or engine run time.

best i can suggest,

sooner you get ontop of this issue the better off you will be, waiting only makes recovery more difficult if not impossible.

fwiw

bob g

[Jedon]

I was just talking to another off grid guy at the ham radio shop and he said I needed 27 hours at 22amps to charge that many batteries so maybe I'm just not ever charging them all the way since I only do 8 hours max and usually more like 4.

When I have time in a month I'll do all the hydrometer testing. For now I'll take one of the two banks offline and see if I can charge that one up.

[bob g]

bear in mind while you wait a month to do the hydrometer thing

the normal sulfation from discharge has more than ample time to harden

crystallize and make equalization extremely difficult if not impossible.

this is one thing i would not wait to do, the longer you wait, the better chance

you will have a bunch of junk batteries to contend with and replace.

bob g

[Jedon]

Well I'll keep using them in the meantime but if I don't get my house finished in the next month the batteries aren't going to matter, I'll probably lose everything anyway. They had already been sitting for a year or so before I got them.

[Ungrounded Lightning Rod]

Start by topping off the water and doing an equalizing charge on each bank of flooded batteries.  After that you can worry about how dead the individual cells are.

[Ungrounded Lightning Rod]

Yep:  Gotta keep those priorities straight.

You can always get more batteries later.  Getting another house is a much bigger deal.

[scoraigwind]

Check the voltages of the individual L16s and then re-arrange them so all of the best ones are in one string that you use.  Charge the other string with the lower voltage batteries whenever you can but do not discharge it.  If you want to keep your batteries then you will indeed need to charge them long and hard.  Buy a load of fuel.