Try This:

http://www.type2.com/library/camper/fripro.htm

>I have a couple questions about the current discussion regarding the
>aux battery:
>
>1)  I realize you are suppose to operate the fridge on 12 volts,
>while enroute, but could you safely use propane?
>2)  approximately how many hours will the propane last, if used only
>for the fridge?
>
>Larry - Charlotte NC
>89 Westy - Gypsy Rose