If by "switch to battery" you mean the 110v outlets, microwave, air conditioner, that is normal. None of them do that unless equipped with a LARGE and EXPENSIVE inverter and battery bank.
How many batteries do you have?
Bobbo and Lin
2017 F-150 XLT 4x4 SuperCab w/Max Tow Package 3.5l EcoBoost V6
2017 Airstream Flying Cloud 23FB