Battery Maintenance, How to fix / improve an older set of SLA 12v 10a batteries?
I have a 36v scooter and have 6 older batteries that I'd guess I won't be putting into my bike again but I do use them currently for a few solar panels I have. I've heard of different acid concoctions or simply adding water. They are all still usable and hover around 12.8 to 13 (a few days after charging) and 2 of them take a sharp dive at 12.5 and go dead fast.
Any advice for trying to resurrect older batteries? A kit, a link, a forum (can't find it here) on how to improve them at least? It also doesn't make a lot of sense to put money into them so the cheaper the better.
If the batteries are standard Lead Acid, you could try Bat-Aid tablets.
Typically the tablets/powders break up the sulfate crystals but the reaction permanently removes some of the sulfur and turns it into sediment at the bottom of the case. Result is less sulfur in solution and reduced capacity. Better approach is to use a desulfator (batterytechsolutions.com or other) which uses a 1KHz pulse to break up the sulfate crystals and allows the sulfur to renter the sulfuric acid solution.
I've had good results with simply adding distilled water and charging them back up.
I fill them all the way to the top with a syringe, then charge them with the caps off and let them bubble over. Of course, you'll have to manage the acid splatter all over the place. I do this in a plastic tray with a damp towel draped over it. Not touching the charger leads, of course.
When it's all charged, I use the syringe to reduce the level in each cell to leave an air gap at the top. This isnt' rocket surgery, just keep the cell barely submerged and it's good enough.
If you glue the top back on, be sure to leave an air gap so gases can escape. I have a 24V pack on a razor MX350 that I run vent tubes to each cell rather than cap them off. I don't know if this is a good idea or not (evap?) but it's a recent trial on some rather old batteries so we'll see what happens. I think I'll pipe them to a small manifold inside the plastic pack and put a plug in it, treat it like a spit valve on a trumpet.