US Patent 8381852 Multiple battery system of a motor vehicle

An electrical system for a motor vehicle includes first and second battery sets. The first battery set generally supplies power to vehicle electrical loads while the second battery set is used to energize the engine starter system. The vehicle's engine driven alternator is connected to recharge the first battery set. Recharging of the second battery set is provided by a charger connected to draw power from the first set and to transfer the power to the second set.