Two sla batterys don't want to go over 12.3 volts

[joshnz]

I got these two sla batterys from a ups that was left on and drained to 0 volts.
I have got them to charge to around 12.3 volts but when I try to go to 13.8 they start to get very warm about 30 to 40 c at 1 amp.
I have been charging them at 400ma and they still get warm and voltage does not seem to increase should I just give up?

[domas]

Re: Two sla batterys don't want to go over 12.3 volts

try using desulphator

[eccerr0r]

Re: Two sla batterys don't want to go over 12.3 volts

Give up.
If you can't get the SLA battery to 2*(number of cells) OCV, likely there's a shorted cell in the pack, and no desulfater will fix that.

I ran across a bunch of these shorted cell packs, if you can still use the pack with a lower voltage, great, but likely it's time for the trash.

[kc8adu]

Re: Two sla batterys don't want to go over 12.3 volts

dendrites.
they are done.
had 2 nearly new mk wheelchair batteries that acted like that.they were left at 0v 6 months.normally i can bring them around but they were essentially shorted.albeit high resistance shorts.

[joshnz]

Re: Two sla batterys don't want to go over 12.3 volts

Ok I am going to try discharging and recharging a few times and see if that helps.

Otherwise I can just use them for another purpose that won't try charging to 13.5 - 13.8 volts.

[japlytic]

Re: Two sla batterys don't want to go over 12.3 volts

As far as I know, there are no desulphators that work on SLA batteries - the only ones I've seen work on flooded lead-acid batteries.

[eccerr0r]

Re: Two sla batterys don't want to go over 12.3 volts

6-cell SLA cells should easily hit 14+ volts at full charge. Remember to let the battery sit for a while (few hours) before measuring voltage, if a SLA pack won't stay above 13 volts, that pack is shorted. Likely a battery pack that has a shorted cell also will have high self-discharge and probably should head to the recycle bin.

I was about to say discarded but please don't discard lead... Recycle it.

[joshnz]

Re: Two sla batterys don't want to go over 12.3 volts

Yea 1 battery does have a shorted cell running my fingers along the side one cell on one battery gets hot. I'll see if the other has same fault.

[eccerr0r]

Re: Two sla batterys don't want to go over 12.3 volts

Actually the hot cells are the ones that are still OK, cold ones tend to be the shorted ones...

[ben7]

Re: Two sla batterys don't want to go over 12.3 volts

Actually the hot cells are the ones that are still OK, cold ones tend to be the shorted ones...

Yep.

Also, I have heard that you can discharge a capacitor into the capacitor, in hopes that the dendrite will melt/vaporize. However, there is only a small chance that it will work, AND, it has a chance of growing back again.

I say just give up on them. Not worth the time, unless you want to try...

[infringer]

Re: Two sla batterys don't want to go over 12.3 volts

yes flooded lead acid is known to be repaired with epson salt finely crushed mixed and cooked to 160° F but their is a science behind it it has to be x parts water to x parts epson salt and then it has to be recharged on a slow trickle for the battery to undergo the chemical reaction that is supposed to properly take place.

Anyhow I know nothing of SLA based batteries I guess it is a new interesting thing I'll have to look into dunno why but batteries have been of interest to me lately.

[eccerr0r]

Re: Two sla batterys don't want to go over 12.3 volts

Word from the wise, again: toss the SLA batteries that don't reach full expected voltage, unless you can deal (both charge and use) with the lower voltage...

[joshnz]

Re: Two sla batterys don't want to go over 12.3 volts

Yea I have given up on them.