Get familiar with how the truck alternator, converter charger, house batteries and auxiliary battery switch etc., work together in typical operation of RV's to charge the house batteries. Most of RV appliances have controls that operate on DC battery voltage. Learn how to keep battery connections clean and battery electrolyte levels above the plates and how to check voltage and charging of batteries with a simple digital voltmeter. It'll help prevent problems while you are camping. If batteries etc., are in good condition, you may have power while camped, and not connected to "shore power", for up to three days. The batteries charge quickly while you are driving, they charge slowly when connected to shore power. ( Exception, some modern converter/chargers may have a faster recharge mode when batteries are low.)