How a van power system works

Most camper van and RV electrical systems follow the same pattern: charging sources fill a house battery, and the battery feeds your appliances.

The parts

Alternator and DC-DC charger. The engine's alternator charges the house battery while you drive. A DC-DC charger sits in between to give the house battery the right charge profile and limit current.
Solar and charge controller. Panels make DC power that varies with sunlight. A charge controller (MPPT or PWM) regulates it to safely charge the battery.
Shore power. At a campground, a 120V AC hookup runs a battery charger and can power AC loads directly.
House battery and BMS. Separate from the engine's starter battery. Lithium batteries include a BMS that protects against overcharge, over-discharge, short circuits and, in many, charging when too cold.
Inverter. Converts the battery's 12V DC into 120V AC for household-style outlets.
DC fuse panel. Distributes 12V DC to lights, fans, pumps and many fridges, with a fuse or breaker on each circuit.

Wiring, fusing and wire sizing matter for safety. Follow the equipment makers' manuals, and use a qualified installer if you are unsure.