Over heating 12 volt flooded batteries

[mdmarmd]

One of the RV owners in my camp had a problem with his batteries dangerously overheating. I wasn't involved but I heard that he had two flooded batteries in parallel. The camp manager came around and smelled an odor and initially thought someone was discharging their tanks. But he could tell the odor was too strong and was coming from the front compartment of this older Alpine RV. He opened up the compartment and found that the two batteries were "melting" and disconnected them. It took 4 hours of cooling before he could remove them.

About two years ago, another RV, a 2017 Montana Highland also had an over heated battery that almost caught fire. Again, people were alerted by the strong smell of, probably hydrogen sulfide gas, emanating from the RV.

The camp manager told my friend that this is the third time this has happened in the camp and he advised that batteries be disconnected when you are gone. But actually both these recent events occurred when the occupants were using their RVs.

My understanding is that a modern charger should have circuitry that will detect when the batteries are topped up and then automatically switch to a maintenance or trickle charge mode.

I thought maybe this overheating occurs if the water levels in a flooded cell drops below the plates and maybe leads to warping of the plates and short circuiting. But all I could find resulting from low water was sulfation and resultant loss of charging effectiveness. I didn't see anything about this causing the battery to overheat.

So, I would appreciate any input on what may be happening here and how to prevent it.

Thanks,

Doug

 

[AZ Traveler]

Doug,

This is likely cause by a failure of the converter.

 

[twindman]

My truck had a battery that apparently close to burning. It wouldn't start my truck, but I got a jump and drove about 5 miles to a dealer. They came and told me they couldn't work on it, as it was boiling over! Don't know what happened, but that was the only time it happened. So apparently batteries can just go bad!

 

[Carl n Susan]

The smell of hydrogen sulfide (rotten eggs) gas, is an indicator of an internally shorted battery. The short causes the electrolyte to boil which produces the odor. The battery can get very hot and melt, but supposedly, the temp is well below the flash point of fire. If the battery case melts and cracks open then you have a serious acid problem to deal with.

 

[mdmarmd]

Thanks for the input.

This is likely cause by a failure of the converter.

Does this likely mean that the convertor is failing to detect that the battery is fully charged and continues to reduce the current so the battery is dangerously overcharged?

 

[Carl n Susan]

While the converter could be at fault, the more likely cause is the shorted cells in the battery preventing the converter from knowing the voltage and it keeps bulk charging as it believes the battery is low.

 

[mdmarmd]

Thanks for your input

 

[jimborokz]

Once, years ago in another camper I awoke in the middle of the night and smelled the rotten eggs. I had thought it was my wife, and it turned out she was awake the thought it was me and neither of us had said anything.
Anyway, investigation found one of our two batteries was boiling over. I disconnected it and went back to sleep. We just took that battery out of service and disposed of it and continued on with just the one battery until we traded it for our Montana. I believed it was just and internal short in the battery.