Battery charging issues.

[wyodave]

Ok here we go. I have had out Minnie 24 foot for 10 years. When we use our batteries everything works great, the main thing is the heater. When I plug it into shore power it seems the charging rate is going crazy. I measured at a 12 volt socket one time and it was 16 vdc. The weird thing is my heater doesn't work, I think the voltage is too high. I had a dealer look at the heater one time and they said it was fine, I ended up taking it apart and everything was ok. Anyone have a suggestion?

[RJay]

When is the last time you checked your batteries(cleaned, checked connections, water etc.). What is the battery voltage when the heater isn't on?

[wyodave]

I forgot to mention other things. You have to excuse me, I work midnights and I was up for almost 24 hrs when I wrote this. I changed my batteries about 6 years ago. I move from Alaska 4 years ago to Wyoming. I stayed at a KOA for 3 months and cooked the batteries not realizing it until I left the KOA. Since it was summer time I didn't use the heater. I know for a fact that the heater does not work when I am on short power, it never has. I believe the voltage is too high when I am plugged in. It seems weird but... Is there a safety switch in the igniter if the voltage is too high? I know for a fact that voltage for the 12 volt light sockets is 16 volts DC when plugged into shore power. I am a locomotive electrician by trade and I know a little something about this kinda stuff. I really don't want to get a new set of batteries until I get this problem resolved. Thank you for all the help from anyone.