Equalize 48V bank of 16 L16's from 47V?

[Jedon]

I didn't get around to hooking them all back up until last weekend and when I plugged them into the Xantrex 5548 it showed 46V, I hooked it up to my 6500W Onan gas genny and charged them until I ran out of gas a few hours later and they were then showing 47.1V. Should I just continue to let them charge normally or tell the inverter/charger to do an equalization? How long should it take the batteries to get a full charge? They haven't been used much in a year or two according to the guy I got them from a few months back. I have two SG testers but can't figure out how to use them. The batteries are hooked in series and parallel for 48V, pretty standard. The Xantrex has a two stage charger bulk/float. My generator can only do 20A through the standard 110V without tripping it's breaker, it does have a 30A plug but I would have to rig something up to use it, or I could come off the 220 but I'm not sure how the inverter would handle that.

Thanks!

-Jedon

[Ungrounded Lightning Rod]

How long did they sit after you go them?

(Just out of curiosity...)

[wpowokal]

Jedon, short answer buy heaps more fuel and keep charging, depending on total amp/h of bank verses charge current from your inverter charger how many hours it will take, but a wild guess 16 hours.

Just use the bulk charge for now, ensure the batteries are adequately watered and go for it.

For checking SG read here (I googled SG of lead acid batteries)  http://www.batterystuff.com/tutorial_battery.html

Allan down under

[halfcrazy]

roughly figuring you have 20 amps ac so that will be close to 40 amps dc with no losses but if memory serves you will get like 1.5 ish amps for avery ac amp taken in.

So we will assume 30 amps into the batteries and you have 2 strings of around 400 amp hours each so 800 divided by 30 amps looks like about 27 hours to full charge?

[Ungrounded Lightning Rod]

I'd:

 - get a LOT more fuel

 - top off the water

 - charge them until the charger thinks they're full (bulk + finishing)

 - let it float an hour or so, then

 - do an equalizing charge, and

 - top off any cells that gassed away a significant amount of water.

The equalizing charge may need to take a LONG time if some of the cells are significantly more discharged than others.  An equalizing charge consists of forcing enough current through the fully-charged cells (electrolyzing their water) to finish charging those that aren't full yet.

I'd unhook the parallel strings and do it to each separately, to avoid possible problems if there's a bad cell in the mix.  Then I'd check the specific gravities and compare the voltages once the surface charge is off.

If they seem pretty well matched I'd tie 'em together, run the charger a while longer until it's done another finishing charge (so the less-charged string comes to full charge from the charger rather than by discharging the more-full string), maybe equalize a little more for good luck, and call it installed.  If they seem off it's diagnose-and-fix, and see if I can get a good string out of what I have.

[Jedon]

I got them November 20th 2008 and haven't charged them since then.

[Jedon]

Thank you all so much, I'll charge one bank at a time for this weekend, then the other bank next weekend, then I'll equalize them one bank at a time. I have 20g of gas now so that should get me through the next 3 days.

[bob g]

you mention having enough to require series and parallel connections to make up

a 48 volt bank?

so this is what i would do if i were you

get out a notebook and a pencil, you are going to need it anyway

start a log book for each battery, and each cell of each battery.

learn how to read the hydrometer, this is your friend and very necessary at this

point to find out what you have.

seperate the batteries into at least two groups, those that have fairly good and even specific gravities, and those with low or uneven specific gravities.

put all the good ones aside for a bit, you will be coming back to them soon.

take the poor condition ones and put them into a string that makes for 48 volts

make sure they are all full of distilled water, and put the string on a charger

and set it to equalize them. it might take 24 or more hours depending on the size of the cells and the capacity of the charger. keep an eye out for battery temperatures, stop charging if they get over about 100 degree's F and let them cool down. while they are cooling is a good time to switch over and begin charging the good string of batteries.

anyway keep watching the specific gravity and charging until they stop rising, after

which let them rest over night and recheck specific gravity and voltage.

if after you have done all this and you still have a battery or so with one cell that is just not responding, you may have to resort to more drastic measures, and

go back and apply more equalization charging to that battery.

some just won't come back, so you don't want to reintroduce bad or questionable ones into a string of otherwise good batteries, because that bad one will degrade the charging of all the others in the string and lead to undercharging and damage to other good cells.

when you are finally done and satisfied you have them all back in shape, log each batteries fully charged voltage and its fully charged specific gravity (each cell)

and date the entry. (let the cells rest for 24 hours before doing so)

then the next time you check up on your batteries you can tell if you are charging them correctly, if there is another bad battery starting to go south, or other issues taking place.

without your log, its a crap shoot and an excersize in memory.

bob g

[Ungrounded Lightning Rod]

Remember that after you have added water it needs to mix in.  Sucking the top fluid in and out of the hydrometer a few times will help but I wouldn't count on it to do the full job.  The heating and bubbling from charging will do that over an hour or so (or discharging over a longer time).  So don't sweat measuring the specific gravity right after topping 'em off - wait until you've worked 'em a bit.

Tipping or shaking 'em can mix 'em - eventually.  And it can also spill acid all over you so don't attempt it.

[Ungrounded Lightning Rod]

You may need to cycle 'em a few times to get them back to their max potential.