Is there anything I can do for a dead SLA battery?

zmoz · #1 08-14-2003, 01:56 PM

I have an ~18 amp hour SLA battery that is in one of those portable jump start things. I've had it for about a year and a half, it's been mostly dead for most of that time. It works for a little while if I plug small devices into it, holding maybe 2 amp hours. If I try and jump start with it, it's worse than the battery I am jumping. When I charge it, it shows it's charged up within a few hours, should take around 12 hours. It was never abused very much, I have another one of these things that has just been beat to hell and it still works great. Is there anything I can do to try and "revive" the battery?

GJW · #2 08-14-2003, 02:01 PM

Usually not but we have had some luck with this:
AccuMate Charger
It's brought a few batteries back from the dead for us.
We bought ours from England but there are US distributors now.

zmoz · #3 08-14-2003, 02:06 PM

What exactly does that thing do to help the batteries? I'm sure that's a nice charger, but if I had to buy something like that I would just get a new battery. Would it help to do something like give it alot of amps for a short time? Or higher voltage? Or something similar?

GJW · #4 08-14-2003, 02:09 PM

Nope, nope, and nope.
It's just a charger that's had some luck reviving a few batteries that wouldn't otherwise take a charge.
For 2 batteries it's probably not worth it but here we use hundreds.

batterystation · #5 08-14-2003, 02:12 PM

What usually happens to SLA batteries is they dry up. They have lost their water. If this is the case, it is shot. SLA batteries also HATE to be stored in the "dead" mode. That will do them in too. If anyone has SLA/gel cell batteries on the shelf, CHARGE THEM while in storage on a monthly basis.

zmoz · #6 08-14-2003, 02:28 PM

But how could this one have gotten that way in the first place? It wasn't very old when it stopped working, I might have discharged it completely once, and that's it. I have another just like it that is about 5 years old. I used to discharge it completely before charging it because I thought that was good for it. [img]/ubbthreads/images/graemlins/smile.gif[/img] I have left it dead for months...overcharged it for days. Still will start up my boat just fine which need 1000 cranking amps minimum.

Brock · #7 08-14-2003, 10:40 PM

Just unlucky I guess, or I should say lucky with the older one. Heres what I would do before I tossed it. Take in on you boat, once it's started and running connect it to the house or main battery and let it take the full charge from the alternator. It won't get any higher then any of the batteries on the system. Or if your boat is big and has a shore power charger you could turn that on and again connect it to the batteries. You could do this with a car, but it should be connected right at the battery and that is a LOT harder to drive and have it connected under the hood [img]/ubbthreads/images/graemlins/wink.gif[/img]

Having said that the battery could leak or crack, or worst case even explode, but I would put odds of exploding about 10,000 to 1. Leaking on the other hand would be about 50 to 1. So if you can put the whole thing in a 5 gal pail, just in case, that is what I would do. Oh the odds that this might bring it back to life are about 1 in 8, maybe. Remember this is just my opinion and just what I would do, do so at your own risk. I will add that I have semi-revived a couple of SLA this way, about 1 in 8 [img]/ubbthreads/images/graemlins/wink.gif[/img]

zmoz · #8 08-15-2003, 01:45 AM

Well...I guess if I've got nothing else to do I can try it. I've got a generator that I made from a lawnmower engine and a car alternator...I'll just hook it up to that. [img]/ubbthreads/images/graemlins/smile.gif[/img]

snakebite · #9 08-15-2003, 03:48 PM

it has sulphated.
you may be able to recover it by float charging at 15v a week or so.if not its time to recycle it.

LED_ASAP · #10 08-15-2003, 06:02 PM

One thing that worked for me was---scarey as it sounds---charge the battery with low voltage, low current AC power [img]/ubbthreads/images/graemlins/grin.gif[/img]

My experience was with a tiny battery used in a Sony walkman, about 2V/1Ah. It won't hold power for more than 10 min playing time and I didn't want to fish out $70 to get a new one. So I hooked it up in series to a small 6V transformer and a ~5V/0.3A bi-pin bulb. Initially the bulb didn't lit at all, but after a few hours it started to glow and eventually got pretty bright. Then it was hooked to the walkman and it charged OK.

For your 18Ah battery, I think you need to find something that will handle a couple of amps, like the turn-signal bulb for cars, and hook it up to something like 16V AC(assume the battery is 12V).

Even if you can revive the battery to some extent, it won't perform as well as new batteries. Lead-Acid batteries won't be damaged by slight over charging, but will be seriously damaged if allowed to run flat. So charge them after each use, and once every 6 months or so if sitting on the shelf.

snakebite · #11 08-16-2003, 01:14 AM

i once recovered a badly sulphated gellcell from a ups that had been left on for 2 years by using 120vac!
used a 1n4007 and a 7w nightlight to charge it.
the higher voltage helped to break down the sulphation.
in your case i would get a new battery for the jump box and play with the old one.starting a car with a dead battery is a pretty demanding application for a small sla.

[ QUOTE ]
LED mods As Small As Possible said:
One thing that worked for me was---scarey as it sounds---charge the battery with low voltage, low current AC power [img]/ubbthreads/images/graemlins/grin.gif[/img]

My experience was with a tiny battery used in a Sony walkman, about 2V/1Ah. It won't hold power for more than 10 min playing time and I didn't want to fish out $70 to get a new one. So I hooked it up in series to a small 6V transformer and a ~5V/0.3A bi-pin bulb. Initially the bulb didn't lit at all, but after a few hours it started to glow and eventually got pretty bright. Then it was hooked to the walkman and it charged OK.

For your 18Ah battery, I think you need to find something that will handle a couple of amps, like the turn-signal bulb for cars, and hook it up to something like 16V AC(assume the battery is 12V).

Even if you can revive the battery to some extent, it won't perform as well as new batteries. Lead-Acid batteries won't be damaged by slight over charging, but will be seriously damaged if allowed to run flat. So charge them after each use, and once every 6 months or so if sitting on the shelf.

[/ QUOTE ]

Ray_of_Light · #12 08-16-2003, 01:44 PM

Add some sulphuric acid at 36 Be (Baume degrees, indicated a concentration of about 30 percent) and reverse charge the battery for half hour. (10 percent of battery capacity)
Start a normal charge then, and discharge the battery with a bulb, 12V 20 W.

Repeat the reverse charge up to three times. This should take the lead sulphate off the plates. If, after the third reverse charge, and a subsequent full normal charge, you do not get the full capacity, the plates are irrimediably destroyed ad you should discard the battery.

Anthony

Brock · #13 08-16-2003, 04:35 PM

The problem with leaving it sit on a charger, or overcharging it, is it is a sealed battery. You can't add acid, so overcharging it will cause it to vent gasses or leak. Once it's gone you can't add any back in. That is why I recommended charging it at a higher voltage, but in parallel with another 12v battery.

zmoz, the lawnmower charger should work, but might not since the SLA might be stable enough for the alternator to work correctly, but it's worth a shot.

LED_ASAP · #14 08-16-2003, 06:32 PM

[ QUOTE ]
Brock said:
That is why I recommended charging it at a higher voltage, but in parallel with another 12v battery.

[/ QUOTE ]

No no, charging it parallel with a good battery will only cause that good battery to sink all the current as that is the lowest resistance pathway.

The_LED_Museum · #15 08-16-2003, 06:37 PM

If the plates are sulfated, you're probably SOL.
Lead sulfate is a spongy material that is nonreactive (it doesn't produce electricity, and cannot be charged up), and can form on the surface of the plates with as little as 24 hours of "dead" time. That's why you often see admonishments that you should never run a lead acid battery (especially a SLA battery) to the ground, and to charge it fully within 24 hours if you do discharge it significantly.

Now, I wasn't aware you could dislodge lead sulfate with AC or reverse-charging...usually when a battery becomes sulfated, you throw it away and get a new one.

Brock · #16 08-16-2003, 11:19 PM

[ QUOTE ]
No no, charging it parallel with a good battery will only cause that good battery to sink all the current as that is the lowest resistance pathway.

[/ QUOTE ]
This is true if you have a small underpowered charger, but it is a car alternator of larger marine alternator, I can assure you it will bring a weak battery up to voltage. It might not be good for the bad battery, but it will get it up to voltage.