A “battery tender” or similar can sometimes help batteries that aren’t too far gone. And check water levels like the other comment mentioned.
this post was submitted on 02 Jan 2026
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I'll read up on those. I want to have a trickle charger attached to my main power anyway for the known-good batteries in my array to keep them from discharging too far in low production times, so if they hold a charge they'll probably live on one permanently
If the batteries have a cap on top that you can open with just your fingers, you should open it and make sure the lead is submerged in the liquid.
If not, add DI water to cover them.
A few of them are sealed, some have pop tops. The few I have opened are completely dry. My plan for the ones with removable caps I'm planning to fill with distilled water and test, then try to recondition them with a desulfator and see if I can detect any difference. never reconditioned batteries before so it's going to be a learning process. Not sure what, if anything, I can do with the sealed ones, I'm focusing on the ones with caps first.
Some tips: listen for bubbling. If a lead acid battery makes bubbling sound, that means it produces and vents hydrogen. That's not supposed to happen outside a short period at the very end of charging (equalization period).
If it happens early, there could be one or several dead cells, causing other cells to experience overcharging. If it doesn't hold a voltage of at least 2V per cell (6 cells = 12 volts), discontinue using, as a dead cell is then very likely present in the battery.
good note, I'll keep a lookout for that.