Battery blew up?!

porch13

I’m getting ready to replace my FLA back with Discover lithium very soon.  As part of the preparation, last night I pulled the battery back out of the box and and just set them up in the corner.  Came down to the utility room this morning and saw that one of the caps had completely blown off a battery.  The battery didn’t get banged around or anything when moving it any idea what could cause this? The battery is still reading over six volts. 

BB.

Ignition of hydrogen+oxygen inside cell... Cell electrolyte levels low (exposed plates)?

• Battery(ies) were being charged (generating hydrogen)?
• Ignition source nearby (loose cable connection under charge, light source overhead with switch sparking)?
• Very low humidity (nylon/synthetic fabric nearby--somehow got moved and generated static spark)?
• Any sparks (welding/smoking/using a cigarette lighter/candle as a light source, etc.)?
• Internal battery fault (old batteries, corrosion, failed internal bus bar)?
• Batteries old and battery/bank is seeing >~2% rate of charge during float (causes batteries to overheat, excessive gassing, loss of water, etc.)?

My first guesses.

porch13

The bank is six years old and has been consuming a lot of water recently.  It happened some time overnight so they weren’t under any type of charge.   No sparks of any kind nearby.  

I covered the hole and hope the bank can limp along until NAWS gets my new batteries in. 

Ralph Day

Spooky!
I have Surrette S550's as well.  How do the water miser caps perform?  I add about 100-150 ml of water each month or two.  1/2 cup or so

porch13

I think the caps helped quite a bit.  For years I used a very reasonable amount of water.  Recently the amount has gone through the roof.  It’s my fault.  I had one battery that was not like the others and I ignored it instead of pursuing warranty.   That guy took out the whole string.   😕

Riley

Jeeze, my exact batteries. 
Good to know. Now I can be even more obsessed with measurements and watering. 
Mine currently use very little water.