Need some help - going on a trip Thursday (well maybe)

Well I will put it this way, when I am not on shore power and turn on the water heater switch it lights up.

I assumed the heater was drawing power from the battery or the battery charger. I never though about it because we almost always have shore power and I don't use it if we do not.

I will have to check the fuse and circuit breakers. If it is fused it is 12 volt, if it goes through a breaker it will be 120 volts.

I only have a single 12 volt battery so now I am curious.

Thanks for the hint.