Forklift Battry Help

[dexxy]

Hi everyone,

been following the board for about a year and am slowly getting my project going, i'm building a 16 foot swept area 16inch dual-rotor genny.  Will post some pics as soon as I get the parts together.

I recently picked up (well had delivered) an old C&D 36v forklift battery about 935AH 6H from a local scrap dealer.  I'm trying to charge the battery up with a couple of small car battery chargers (charging 12v banks one at a time).  Is there any way to tell if this battery is going to be any good?  Here are my cell voltages after a day of charging:

1. 83 1.90 1.93 1.94 1.83 1.96
   
1. 95 1.99 1.98 1.97 1.95 1.82
   
1. 63 1.90 1.92 1.92 1.90 1.95
   
   

Is there any hope for this thing?  I'm not sure if forklift battery's are supposed to be > 2v per cell? What do you think?

Thanks, dexxy

[disaray1]

dexxy,

 Do you have a battery hydrometer? If not, you should get one. They're not expensive. Checking the specific gravity with a hydrometer is the best way to determine state of charge. Second to that, checking volts will work. In your case, 2.11 volts per cell is what you want, 2.07V is 75% charged, 2.04V is 50% charged and 2.01 is 25% charged.  Sooo...youv'e still got a ways to go. With the small charger there, this may take awile!  Keep charging and checking. Good luck be with you.

 disaray1

[Ungrounded Lightning Rod]

You've only got half as many readings as cells.  You really want to measure all the cells.  (As was pointed out, hydrometer measurements are better, too.)

With the paralleled strings you'll also have some issues with interaction during charging and rejuvination - or any time you have weak cells.

[domwild]

Dexxy,

Have been told that a supposedly "dead" 12V battery, which is still showing 10.5V, is actually OK and may be resurrected via chemical means (EDTA) or desulphation, pulse charging, etc. This probably equates to about 1.7V per cell at rest.

Any sediments can be flushed out via tipping, adding distilled water, more flushing and then adding new battery acid.

[nanotech]

Actually, he's got 18 cells and 18 measurements.  It's just the way Scoop added spaces that screws things up.

[Ungrounded Lightning Rod]

I take it each cell has four posts, not two?  (Now that I look at the picture again I see that there's only one filler cap for every set of four posts.)

[dexxy]

Hi Again,

I've let the battery chargers run for a few days and this is where i'm at:

Top Row : 1.95 2.02 2.04 2.04 1.97 2.07

Middle Row: No charging yet

Bottom Row : 1.95 2.02 2.03 2.03 2.02 2.05

I added EDTA to most of the cells and mixed them up as much as I can, don't know if it's the correct EDTA or not, its called 'Edetate Disodium'  there was a calcium version as well, but couldn't find anything else.

I can't quite dump the electrolyte as the battery weighs 2500+ lbs so I made myself a stirring bit for my hand drill and have tried to help out a bit.

[Shadow]

I wonder if it would work to use air to bubble it to mix? Like a small aquarium pump. Just wondering outloud here...

[altosack]

I'm not sure if you will be able to adequately evaluate the battery with your small charging sources, and you will want to make sure to have a good battery to connect to before you connect up your large wind generator. Sort of a chicken and egg problem.

You will need at least 50A or so to equalize your battery (a good hard equalize is the best way to bubble up your electrolyte). If the battery actually is good, you might get away with as little as 20-30A, but if it doesn't seem to be working, you won't know if the lack of charging is the problem or not.

For a project this big, I would go ahead and invest in a good Todd (or equivalent) charger, or a generator if this is the way you want to go. Note that if you get a generator, you still need a good charge regulator, but if you are building a wind generator, you are going to need this anyway.

I realize you probably want to start slow (and cheap), but once you have the battery, you need to maintain it, or else you can write it off.

Dave

[dexxy]

Well, thanks to some help from my friend and neighbour, an ex-bell guy, I now have 3 20 amp ma-bell battery chargers.  We just took some old booster cables and cut them in half to use for the DC side and used old computer power cords for the input side.

I'm now seeing lots of action in the cells (lots of hydrogen being generated) and I'm actually getting real readings on my hydrometer now.  Voltages per 12v bank with chargers on goes like this:

13. 14v (had charger on the longest so far, amperage has dropped to about 14 on charger)
    
12. :82v (amps about 18)
    
12. :66v (still using car charger at about 5 amps, will switch as soon as first bank is done)
    
    

I'm worried about a couple of cells, with charger on volts is about 2.04 on my worst cell, another at 2.10, most are averaging about 2.20+ on the mostly charged bank.

Well, thanks for the help!