Gel batteries
Hi. I have acquired two used 135ah 12v gel batteries. They are 5”x18”. They were back batteries that were changed out after a years service. I think they really have no usage. My question is how...
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Not a surprise, 9 times out of 10 a 'gel' battery turns out to be an AGM instead.
I'd bring both upto 14.5v until amps tapered ot about 0.8a each, then let them rest and observe voltage as it settles.
If they are close in resting voltage, I'd have less fear of running them in parallel, but I doubt i'd parallel them with flooded gc-2's during discharge, and would want to top charge them separately.
When fully charged and rested I'd put a relatively high load on each separately, and time and measure voltage held during that load. If one is maintaining 12.53 where the other is 12.34v after the same load for same duration, I'd not use them in parallel for any long term duration.
But the worst that happens is they simply do not last very long. Just don't expect their full capacity when everything is paralleled, discharged then charged together.
Start by fully charging them, letting them rest, and then observing OCV.
I'd bring both upto 14.5v until amps tapered ot about 0.8a each, then let them rest and observe voltage as it settles.
If they are close in resting voltage, I'd have less fear of running them in parallel, but I doubt i'd parallel them with flooded gc-2's during discharge, and would want to top charge them separately.
When fully charged and rested I'd put a relatively high load on each separately, and time and measure voltage held during that load. If one is maintaining 12.53 where the other is 12.34v after the same load for same duration, I'd not use them in parallel for any long term duration.
But the worst that happens is they simply do not last very long. Just don't expect their full capacity when everything is paralleled, discharged then charged together.
Start by fully charging them, letting them rest, and then observing OCV.
