Want to add a battery to my truck camper - help please

The fridges that have the 12vdc cooling capability will pull well over 20 amps when in cooling mode...They are not very efficient in this mode so it will trying to cool most of the time..

If you have the ability to run it with the truck via a wire, it needs to be very hefty... Remember that you have to charge your camper battery (s) too.. In this instant your are into big amps..

I do not have a 3 way fridge and would not even consider it.

Jim