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Reviving a Lead Acid battery...

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FastMHz

Fri Dec 23 2011, 05:58PM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

I managed to get my hands on some used Caterpillar 4D size group batteries. One of them came to me with low water in 3 of the cells, so I leveled 'em up with distilled water. I hooked a Shumaker charger with a desulfate function to the battery. Sure enough, it triggered the desulfate mode. However, the battery still does not work properly.

Symptoms:

Charges to 14-15 volts, charger shuts off and says done
Very low current output, I can't deliver even 25 amps
Self discharges to 9v in less than 24 hours

What I've tried, in order (I know some might be bad, but you can't break it any more so I experimented):

Desulfate charger function 3 times
Forcing overcharge equalization at 15.5v
Charging with 120vDC at 60w for 24 hours
Charging at 60vDC at 300w for 24 hours
Charging at 8000vDC for 12 hours
Physically shaking the battery up

No dice. It can run a single headlight for about 15 minutes. This is a 1500cca battery, it's huge and should not die that fast. And at over $300 a pop, I'd like to restore it.

Anything else I can try? I'm thinking about discharging a 10kv capacitor into it to try and break up the sulfation, or blow apart whatever conductive material is internally shorting it out. As I said, it's already broken so why not try everything to revive it

Merry Christmas!! ~Cev

Steve Conner

Fri Dec 23 2011, 06:04PM

Registered Member #30 Joined: Fri Feb 03 2006, 10:52AM
Location: Glasgow, Scotland
Posts: 6706

Sounds like positive grid corrosion.

FastMHz

Fri Dec 23 2011, 06:40PM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

Yeah, which probably means I can't do a damned thing to restore it.

I just discharged it completely and then discharged a 10kv @ 1uf cap into it 20 or so times. Now it's on a trickle charge...I'm not going to hold my breath though. It's certainly an unconventional technique, that's for sure - but someone's gotta try it, right?

Conundrum

Fri Dec 23 2011, 07:25PM

Registered Member #96 Joined: Thu Feb 09 2006, 05:37PM
Location: CI, Earth
Posts: 4061

Doubtful that this will help.

The fault is more likely to be an internal low resistance at the bottom of one or more of the low cells, caused by abnormal cell conditions.

+Ve corrosion is also likely, however one trick that might work is to drain out ALL the acid, flush the cell(s) with DI water and a gentle agitation from a fish tank bubbler then replace the acid with MgSO4 (aka epsom salts) and charge the battery for a couple of days.
Drain out the MgSO4, flush thrugh with DI water/bubbler and then replace the acid with exactly the right original acid with pH adjusted so each cell is the same with SG corresponding to 30% charge.

Then recharge as normal and compare internal resistance and peak current etc.
Hopefully the low resistance garbage will be flushed out which ought to help the self discharge problem.
(H&S note, DO THIS OUTSIDE with FULL FACE PROTECTION AND GAUNTLETS!!!)

-A

Fulmen

Fri Dec 23 2011, 07:31PM

Registered Member #3883 Joined: Fri May 13 2011, 06:30PM
Location: Norway
Posts: 87

Sounds like a shorted cell, check acid density to confirm. Don't know about epsom salt or the likes, but you could try to drain the cell and flush it. Don't adjust the acid before charging though.

FastMHz

Fri Dec 23 2011, 08:10PM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

Well damn....I won't be doing that stuff...battery acid scares me. Yup, I'm less afraid of a 24kj cap bank than battery acid

radiotech

Fri Dec 23 2011, 10:09PM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

It would be good to know the resistance of the bad cells from about 1 to 4 volts.

When this has been recorded you might try: Reverse dischargie cell down to
zero volts at the current you found at the 2 volt forward test.

When has reached zero cell volts, give it a boot of about 40 amps reverse for
a second or two. Then recharge it forward and see if you get a better resistance result.

I have awakened some batteries this way, so they ballast the alternator with a reasonable
voltage, and work lights etc with the engine running.

But they wont hold a charge long.

If you can do lead strap brazing, you could pull good plate assemblies from what you have
to make up a god battery.

And wear a face mask. Battery acid is nasty stuff if a cell ruptures.

FastMHz

Sun Dec 25 2011, 01:11AM

Registered Member #179 Joined: Thu Feb 16 2006, 02:08AM
Location: Hagerstown, Maryland - Close to Prime Outlets
Posts: 287

I've been reading around the web, and the reverse charge treatment is mentioned a few times to more forcefully desulfate dead batteries. So I killed the battery to as close to 0 volts as I could and then charged it backwards....for about 2 minutes and it emitted what smells like ozone...not sure on that though (I know that's not long but I'd like to know if it changed anything and what that smell is). Now I'm attempting to normally charge it again, very slowly. I'll see if there is any improvement whatsoever.

Merry Christmas!! ~Cev

radiotech

Sun Dec 25 2011, 02:48AM

Registered Member #2463 Joined: Wed Nov 11 2009, 03:49AM
Location:
Posts: 1546

My post mentioned a weak cell, not the whole battery.

Electra

Sun Dec 25 2011, 10:11PM

Registered Member #816 Joined: Sun Jun 03 2007, 07:29PM
Location:
Posts: 156

I broke a very old battery open years ago, and the a lot of the plate material had gone so brittle that theyâ€™d disintegrate to the touch, so I cant see that being able to conduct much. The problem is I donâ€™t think they make auto batteryâ€™s out of pure lead but rather some paste like material stuck on a grid. I think it is possible to revive a battery that was in good condition before being left idle for a short while.
But once it gets so far gone most attempts seem futile, unless you can open it easily and physically replace plates. With the plastic welded cases if you have to use a chisel to open it you cant reseal it without the risk of it spilling again.

You can find a faulty cell easily as it bubbles and heats up if you pass large current in/out of the battery.

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