The bigger the battery the better the battery at powering things for a long time.
A group 24 has roughly 75 amp hours, two would give you 150 and if it is a MARINE/Deep cycle you can safely use about 1/4 of that before serious damage happens.
Gropu 27 is roughly 100 amp hours..A pair of those would give you 200,, See notes re Marine/Deep cycle
A pair of six volt GC-2 Golf car batteries (DEEP CYCLE) in series is 230 give or take a bit with a 50% discharge before serious damage starts happening, or 115 usable amp hours.
NOTE: IF you choose to go the 6 volt way I will now answer all your six volt battery questions.
This is a 12 volt battery.
0-{Battery}+12
This is a pair of six volt
0-{Bat}{Ery}+12
Yup, as you cansee the two, connected in series, make one BIG 12 volt battery, think of them that way, treat them that way, the only time you treat them as six volt is when you remove them from the RV... That is because they are heavy and it's easier to lift just one at a time.
