Charge controller for Gel-cel batteries

Hi all,
I’ve got 4x gel batteries I’ve been told are 240Wh, however I’m unsure of their current state.
I’m curious if anyone’s got any experience with these, or is familiar with the sort of charge controller they need. I’d rather not spend too much before I know of they’re working, but if there was an easy way to find out I might try throwing them in my car/building a UPS or something.
Additionally, if anyone wants to play with them or anything, feel free. If I can’t think of something to use them for, they’ll be up for grabs.
Cheers, Ryan

More likely 24Wh. Or less.

Probably a straight 12V lead-acid? If so then I have a basic modern car battery charger (Aldi) as well as an old stupid one I used a lot for 6/12V batteries.

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If they’re happy running on standard lead-acid chargers then I’d appreciate it if you could bring one in some time so we could hook a cell up for a few hours and see how it responds.

Hi Eyal,
Thanks for bringing in your charger yesterday so we could test the batteries, it’s unfortunate that they’re not taking charge but I appreciate your help none the less.
I’ve done some looking around and for batteries with nearly no voltage and that don’t take current, I’ve had people suggest a battery desulfator to clean the internal plates.
Because such a device is relatively cheap and could come in handy anyway, I’ll buy one and see if it has any noticeable effect.

I know little about SLA batteries but a chemical attack should probably have an effect, however in your case you will need to also physically breach the battery case. Do a search to see if there is info/video of doing this to this specific battery.

Surely others on this forum visited this situation before?

Should be fun but be careful.

Is the charger putting any current into them? Often ‘smart chargers’ won’t attempt to charge a battery with zero V across the terminals.

If that’s the case, use a lab power supply with the current limit at a couple of amps and voltage limit @ ~14V and give them a couple of hours. Don’t leave them unattended, if you have a shorted cell then one of the safety vents will pop. Nothing catastrophic like Li-Ion, but not great.

Having said that, gel batteries that had been run to zero for a long period I’ve never tried to recover.

@Harvs, we tried a lab power supply and got absolutely no current through. :-(

Best of luck then!

Desulphators iirc tend to smack the battery pretty hard to try and shock the sulphur off the plates, the problem is if that causes offgassing then it has the very real potential of ruining the battery through bubbles getting trapped in the gell, which actually may very well be the issue, either bubbles trapped in the gell or mechanical damage to the plates within the battery.

Chemical may not work either, if memory serves the gell is very viscous so I am not sure how well chemical addatives would work. Though cracking open the battery if not too destructive would shed some light as to whether there is any mech damage.



Given the battery’s are already completely dead as is, and I have four of them, I’d say I have room to play around a little. Perhaps desulphate one, and if that doesn’t work, crack it open.