Hi guys.  I have some oldish silver calcium 200Ah solar batteries in a bank.  2 of them were overheating so I decided to unseal them, by removing the covering sticker, and top them up with distilled water.  Unfortunately one of the bottles I had bought was contaminated, I'm not sure with what, it started foaming out the top of the cell like washing up liquid.  Thinking of draining that cell and refilling - does anyone know the specs of what should go in there??  Or what other curative measures I could try?

And while I'm here, any ideas why 2 out of my 4 batteries would overheat and the other 2 not?

Many thanks

I've always removed the stickers to check the electrolyte in these 'sealed' silver calcium batteries.

They need water almost as often as regular lead-acid batteries.