Bulging battery-is it ruined?

[boatpoker]

Originally Posted by a64pilot

Of course they do, any thing does doesn’t it?
However an AGM battery is a VRSLAB, that is valve regulated sealed lead acid battery, there is a valve, an AGM will vent gasses, but must build up enough pressure for the valve to open before it does, so a slightly bulging AGM means nothing, nor does a slightly caved in looking AGM. Short an AGM and it will hiss at you, just like any battery will as it vents gases, just under normal conditions, they don’t vent, they recombine gases back into water.
Read here on Lifeline’s manual where it says what causes bulging or caved in looking end walls.
Attachment 161756

it's not the only case I've seen of swollen and burst AGM's regardless of what the manufacturers marketing department says.