Welcome to RVing. FYI - There are several things in an RV that are 12V powered even though you are hooked up to AC shore power. These include lights, refrig, heat, attic exhaust fans and any slides, electric jacks etc. When you go dry camping (no shore power etc) you will have to learn to watch your battery consumption, unless you have a generator.
F250 HD 7.3 Diesel :)
31 Ft RLS Designer 5th Wheel :D