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What is the best way to charge a 12v 26A sealed lead-acid battery? Answered

Hello Everyone,

I have two sealed lead acid batteries, 12V and 26A.  What would the best way to charge these be?  I have a small 12v float charger, would this normally be adequate?  The charger says not to use on a battery with less than 9.6 volts.  Both batteries are hanging around the 5.7-5.9v range.  For a battery requiring this much charge, what is the best option (without purchasing a specialized charger).  Building one will not be a problem.

Thank you for your time!



They're close to dead - they may well have sulphated. TRY charging them with a good, big constanf voltage supply, and DO NOT exceed 2 A charging current by fiddling with the voltage selection - less would be OK, but not more than capacity/10 . It will gradually charge and get to the point your original charger can take over.

Had to remove the best answer for an addt'l question. My apologies.

I have a charger that came with a used electric wheelchair I recently acquired. The charger output is rated at 24v 3A DC. It is labeled a "Fully Automatic Battery Charger". The output cable has 3 pins. If my two 12v 26 A batteries are connected in series, might this charger be suitable for recharging depleted sealed lead-acid batts? The charger was designed for use with two 12v gel type batteries.

Again, thank you for all your help!

I wouldn't.

these sound like old batteries,and/or very flat. stick with the very gentle charge for abit.

incidentally this was a different question.. .By asking it as different question it makes it easier for i urges to find a helpful answer....

Would a standard 12v float charger be ok to use on a sealed lead acid? The charger is small and cheap, providing 600mA of charging current.

Thank you for your response.

600mA is fine - it won't charge very quickly at all though. FAST charging SLAs can be problematic, slow, not so much.


Speed isn't a concern right now. What problems could arise from using such a charger with a battery with under 50% life?

It'll blow a fuse, because the current the battery will draw will be more than it can cope with, or it will just refuse to charge it - many have undervolt detection.

Thanks for all of this battery advice! You've answered every battery question I have right now. Very appreciated. :)