THOR Battery Chargers provide an optional automatic charging system in three steps. A fast charge to bring a good, drained battery back up to full voltage rapidly (“Boost”). A standard charge to bring the battery up to a full charge at a safe rate to prolong the life of the battery and provide power to run 12V lighting and appliances in the vehicle/device (“Normal”). 3. A trickle charge to keep the battery fresh during times of load inactivity (“Storage”). The charger automatically changes modes to accommodate changes in conditions.