Why did my battery blow up?
 

My son decided to fire up our 68 bird and when he turned the key, boom. I had the battery on a trickle charger all winter and I started it every month or so, Any ideas why a battery would just blow like that?

Accumulation of hydrogen gas.

Sorry to hear this news...did it cause any damage to your car?

Vince

Could very well be accumulation of hydrogen in the vicinity of the batt plus a spark and there goes the boom.

George

The most common reason for the spark is a bad connection at the batery post. It could also be an internal problem of the battery. Be sure to have clean and tight battery connections.

I think maybe you are correct about the cables being loose on the terminals, thanks for the tip. I'm going to be more dilligent about that going forward. Luckily, no damage under the hood, I washed everything down and dumped a couple of boxes of baking soda over the mess and it cleaned up good. Sams club even gave me a replacement, no questions asked.

One cell may have been low on electrolite.

The plates of a battery can flake off & fall down into the bottom of the battery case & that can cause a dead short across the plates & when that happens the bottom of the battery will act like a stick of dynamite & blow out the bottom of a battery but looks like the entire battery blew up. The batteries that do that are usually older & at a low or close to being a dead battery. It usually happens when the battery is under a load which is like what your describing, trying to start it. Glad nothing happened to the car.