Battery Isolators are used to make battery systems completely separate from each other while still remaining in the same system. For example, many of us listen to the car radio without the car running which drains the battery (slightly), but if left on all night, you would come back to a dead battery. A Battery isolator could be used in this situation: Allowing you to have one battery solely for the radio, and use the other for starting. The Isolator would allow the radio to be completely drained, while not allowing it to take energy from the other battery. Battery Isolators have many uses and we hope to have what you're looking for. With our low and competitive pricing we strive to be your one stop shop for all your battery and battery related needs, here at All Battery Sales and Service Online.