Did I just kill my battery?

[quakefiend420]

It's a deep cycle marine battery rated for 110aH.

I put it on the charger at 10amps at about 8PM, set an alarm on my phone to check it in an hour. Alarm never went off, I forgot until about midnight. Went down to the garage and it's boiled over

Reads 12.8V right now, guess I'll check it again in the AM.

Think I can add a bit of distilled water and be OK, or did I cook it?

 

[Raizinman]

How hot did it get? Did the sides sort of cave out? Heat is a big enemy of a battery. Overcharging will overheat your battery. I would suggest you first, check battery voltage. Then fill with distilled water. Then let it sit to cool for 24 hours. Then test the battery voltage again. Then you should give is a load test, as you are mainly reading charge voltage. If you see a voltage less than 12.6, you likely fried a cell. Remember, each cell is 2.1 volts. Likely you don't have a load tester. Harbor freight have them for about $40 or you can take the battery to most any auto parts store like Advance and they will test for free.

 

[quakefiend420]

It wasn't really hot from what I could tell, sides look fine.

I'll let it cool overnight and top it off and see how it looks...