HI,
It sort of depends on what size battery it is, how much the weight is (more weight means they store more power) and what year the RV was built. Before 1990, the RV's did not come with CO meter or Propane leak detector, so that saved a lot of battery power.
My 97 RV has the CO and propane detectors, along with the refrigerator will consume 35 amp hours per day.
So if you have a typical pair of group 27 batteries at 100 AH each, you can last about 4 days, using minimal lights and nothing else.
If you have larger 120 pound 8D batteries, they can store 220 amp hours by itself. A typical pair of golf cart batteries together weigh in at 130 pounds, and also store 220 amp hours (used in pairs to make it 12 volts) and can be lifted into the battery compartment in two easy (well 65 pound) lift batteries, with a huge water capacity, and they tend to last longer due to larger battery plates, and less likely to run out of water.
I would also suggest that you look into solar power.
SunElec.com They have some solar panels priced at $1 to $1.50 per rated watt.
Fred.
