Smart 12V Dual Battery Isolator

This voltage sensitive relay module is designed to combine two batteries when charging and isolates each when not charging. It essentially isolates your auxiliary battery from your starter battery to prevent you inadvertently fully discharging it (and thus leaving your car stranded!). Once the voltage of your starter battery rises above 13.3V the isolator engages to charge both batteries in parallel. When the voltage of the starter battery drops below 12.8V the isolator disengages sending charge solely to the starter battery. Fully encapsulated design seals out water and dust.