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

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!


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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.
huck alexander (author)  steveastrouk5 years ago
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....
huck alexander (author)  steveastrouk5 years ago
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.

huck alexander (author)  steveastrouk5 years ago
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.

huck alexander (author)  steveastrouk5 years ago
Thanks for all of this battery advice! You've answered every battery question I have right now. Very appreciated. :)