The REGO DC-DC Battery Charger is equipped with special bidirectional charging technology, providing the most efficient mode of house battery charging from the starter battery while in transit. It also recharges and maintains the starter battery once the house batteries are at maximum capacity. This will work with most common 12V alternators and batteries and has a 4-stage charging system for safe and proper battery maintenance. The REGO DC-DC Battery Charger is ideal for recreational vehicles, commercial vehicles, boats, and yachts, and vans that provide consistent energy whenever you want!