Hi all, I picked up a 6.0V 6Ah SLA battery the other day and it read 4.23V right off the bat. Not bad. Much better than the 0.12V I’m used to seeing.
Tried charging it with a NiMH mode on my hobby charger because it would say “low voltage” at Pb 3S mode, and at 1A, it shot off to 29.98V. This was expected. I then popped the lid, refilled the three vents with distilled water, and started to charge again.
After some stabilizing, I could get my charger to Pb 3S mode, but the voltage wouldn’t rise to 7.20V, which is the CV stage. So I switched over to my PSU and set the voltage limit to 6.80V and the current limit to 1A. Even after an hour, it’s still reading 1A at 5.5V, and the battery’s heating up, 60C I’d say. It’s been about 18 hours since I hooked it up to the PSU.
Should I toss the cell or keep feeding more electrons into it? Thanks.
Did you restore the water levels on each cell? Open carefully and check the water levels, they should cover the plates completely, if low put some distilled water and do some Charge discharge charges, then do a very slow charge for a day or two, hope that helps
Yup, each cell has its electrolytes completely refilled. I’ll be applying a small current over a long period of time, hopefully it’ll restore the cell.
people trying to salvage cheap lead-acid batteries that are total waste and throwing away li-ions that are completely fine, just self-discharged to 1-2 volts
let it go another few hours.the fact its pulling anything is a good sign.i will often rehydrate ones that work but show high ir but in your case you overwatered it.
i use a syringe and look inside with a flashlight.
add just till the seperater loses that flat white look.
prepare a spot in the recycling pile as most of these type of battery are goners or have very little capacity.
I have negative results from most SLA & regular lead acid batteries that I try to restore. mostly SLA
SLA & LA has few failure modes. 90% batteries that build sulphates or dried can restored. other failure modes have very little success.
I found following failure modes:
1. sulphate buildup - Can recover by applying higher voltage than battery (10-20V for 6V, 20-35V for 12V) current limited to 0.05 - 0.1C. will take few hours to days to recover.
2. dried cells (SLA) - Water evaporated. just refill water and charge slowly.
3. plate corrosion - mostly positive plate. recovery impossible. but can use for low rate discharge. I have 12V 7Ah SLA. it can’t supply 12V @ 3A for even 1 minute. but 1A rate, I can get 3-4Ah.
4. cracked cell connector - recovery impossible. some batteries charge and sudden stop charging or discharging.
5. shorted cell - rarely recoverable by applying high current pulse or high current discharge, tapping. battery with shorted cell continue charging and that cause working cells to over charging and gassing. may be dangerous acid spill through vents (I saw it)
