[DON]

It helps immensely if we know your conversion, model of coach, and specifically which batteries are you boiling.

I can give you some very general information based on past posts regarding this topic.

If you are “boiling” your batteries they are being overcharged. If you are using anything other than a 3 stage “smart” charger such as those made by Guest, or your inverters that alone could be the issue.

If you are using your inverters or a smart charger and the batteries are “boiling” you have to insure the settings for the 3 charging stages are correct for the type of batteries, such as charging a gel cell battery to flooded cell voltages is going to ruin the batteries. If you are trying to maintain chassis batteries using a converter installed charger and it is not a 3 stage charger that will ruin a set of batteries in a very short period of time.

You need to provide specifics if we are to be specific in our answers.

[Peter]

Ditto what Jon said, chassis, house, converter, year, etc…

[AL]

I have run into issues with older “gel cell” type batteries boiling over in high temp conditions even when being charged properly.

[Jim/Chris]

At this point we don’t know enough to even guess at the type batteries.

But I agree that gel cell batteries are heat sensitive, and they don’t “boil” over. Those tend to go POP.