Puzzled over battery boil over

pretty much what everyone else said. Check the charging voltage and if it is normal you have a dead cell. A dead cell causes the battery to take a lot more charge than it should causing it to heat up and boil over.

That just happened to the battery in my wifes car. Battery started the car just fine but was boiling over due to a bad cell.

It was 9 years old.

Ive had this happen twice over the past twenty years. Once was attributed to a converter which went bonkers and put out too much voltage .. the other time the battery guy said it was an internal short/dead cell. Have the battery test and determine whether the converter is properly working by measuring the voltage with a multimeter.

In order:

Check charging voltage-- should be in the 13.0-13.2 range when warm ambient temperatures, up to 13.5 when cool.

If in that range, very high likelihood you have a bad cell-- the converter is putting out the proper voltage, BUT, that 13.XX volts is charging a 10 volt battery (one bad cell) not a 12 volt battery. Severe overcharging of remaining cells.

My converter that went bad that was boiling the batteries was pushing over 16!!!

Good info

Clicky

You may need to brush-up on basic battery maintenance which includes finding out voltage values. A cheap digital volt meter is your best friend. Newer breeds of vehicle chassis charging systems do not commonly fail in the "Voltage too high" mode, but you need to check it. Anything higher (at the battery posts) than 14.2 volts is wrong. Seek professional help. If voltage is normal your battery has gone bad.

You converter can boil over a battery in a heartbeat. Mine did. :(

You need to check the output of the converter. And from my experience with 2 different RV mobile repair guys that both said my converter was ok. You have to leave the tester on 'after' it reaches the correct output. That's what the 3rd repair guy did and it skyrocketed off the charts. Which is why my battery was cooking.

When we took it out one capacitor looked like someone shot it with a 22.

Converter was still running but it affected 2 other things in my MH that no one thought to put two and two together to point to the converter. And like a three stooges movie every was 'convinced' the sulphur smell we got a whiff of every now and then was from a well I was parked next to. :S

Overfill can rule out....dead cell and unregulated charge will look further into. Thanks for the response, I tried to google but prolly did not "enter my search correctly".

Some possibilities;
overfilled battery
dead cell in battery
unregulated charging current