Tried starting my moms car today and heard a loud boom from the engine.
Opened the hood and there was smoke and acid everywhere. Top of the battery was blown open and even left a dent on the hood.
Went to buy a new battery at Autozone but they didn't want the core exchange cause the battery is hazardous now.

 

battery too hot ... alternator overcharging the battery ... pressure relief valve (if there was one) on the battery didn't work allowing H2 gas to build up ... battery old and instantaneous curent draw too (damn) great for the battery ... cheap battery ... battery underrated for the starter's current draw ... starter betting old and 'looked' like a short to the battery ... sudden short in the electrical system caused by the starter ... all of the above ... none of the above ... some of the above ...

 

too many beerz for slipstream444 ...

 

[QUOTE]Originally posted by Vash
Tried starting my moms car today and heard a loud boom from the engine.
Opened the hood and there was smoke and acid everywhere. Top of the battery was blown open and even left a dent on the hood.

 

Did you hook up the cables backwards?

 

thanks for the detailed explaination...
i just hope it doesn't happen again, my old battery was Interstate and my new one is Duralast.
thanks again

 

cables are on right,
the person that installed it last knew positive from negative

 

Lead acid batteries normally produce H2 gas during the charging process. This gas collects above the fluid at the top of the battery. Even maintenance free batteries are not completely sealed but an old one will have a worse seal and allow some of the gases to escape slowly. Yours may have also been cracked. When you start the car, all sorts of electrical connections are made, some of which (especially on older vehicles), will produce sparks. The most likely candidate for a spark (in this case) is a poor battery terminal connection. It doesn't take much H2 gas concentration to start an explosion, which will follow the gas trail back to the battery's internal compartment (like a fuse) and set off the more concentrated H2 gas within. Result ................. BIG BOOM!

 

^ Well said

 

My wife had a yard sale the other day and it was late in in afternoon and 95 deg and the last lady left in a 1996 Camry - we hear a boom and she dies at the end of the driveway. It was here lucky day, of course, as as soon as I popped the hood, I saw the blown battery. Kept the kids and gawkers away as there was some acid, washed her down with baking soda and water, and with my trusty Matco 10mm ratcheting wrench, had the old batt out, in the Sube, and on our way to Sears to get her a new batt - they did take the old one by the way, as the lead was intact.

Last week, she sent a nice note, and 3 "Good Samaritan" T-shirts; not required, but a nice gesture.