Hot, smelly batteries

[Gary RVRoamer]

The trickle charger, the voltage between the positive and negative battery cables in the rv, is 13.65.

Is that too high ?

Not really - many charging systems float charge at 13.6 and 13.65 is within the margin of error for meter readings.


I agree with the others that you have one failed battery, likely the older one but not sure without testing. And the newer one may be damaged now too.

[BrassKooler]

Originally Posted by twinboat

There is your problem, one battery failed and they went cheap on you and replaced it. Now the other probably failed too.

That’s what happened! I thought the dealer was just being nice.

I’m too naive.

The hot battery has 11.8 volts in it today and the other one has 12.9.

I’m going battery shopping!

[BrassKooler]

Originally Posted by wolfe10

This will happen if EITHER the converter or charger charges at too high a voltage OR if a battery has a dead or weak cell.


Converter or charger at too high a voltage is easy to verify-- if its FLOAT MODE voltage is over 13.2-13.4 VDC it is too high.


But, a battery with bad cell and a perfect charger will do it as well. One dead cell in a 12 VDC battery= 10 volt battery. Charging a 10 volt battery at 13.2 WILL BOIL IT.


Turn off the converter/charger or disconnect from shore power. Disconnect the batteries and check voltage individually after an hour or so. Better yet, LOAD TEST them.

Today the boiling battery has 11.8 volts in it, the other has 12.9.

You were right!

Thank you!

[THenne1713]

Usually when battery cell goes bad, it will be one cell starts losing water faster, boiling on charge and smelling of sulfur, putting out excess EXPLOSIVE HYDROGEN GAS. This is WHY batteries should always be handled wearing SAFETY GLASSES. While rare, exploding batteries are no joke.

If they are six volt and you do not plan to boondock ever or much, consider a cheap RV/ Marine battery. Your old BATTERIES are likely 5+ years old, some may last 7-10-yrs, but SOME DO NOT.