Bussman SurePower (TM) 100A Bi-directional Battery Isolator Solenoid RB-BS-1315 19-3128

A battery isolator enables each battery to act as an independent power source so that the main battery can conserve power even if the auxiliary battery is fully discharged. When charging, the isolator gives priority to the main battery so that there is always a full charge to start the engine. It operates at 12 Volt DC.