How Battery Isolators Work

Battery isolators allow the charging of multiple batteries from a single power source. This is a particularly useful feature for a car. While traditionally all the electrical power that a car uses is supplied by a single battery that is charged by the alternator while the car’s engine is running, this set-up can occasionally cause problems. If someone uses any of the car’s electrical systems for an extended period of time -- such as the radio or lights -- while the car’s engine is not running, the car’s battery can die, and the car does not start. In order to avoid this type of situation one can use an auxiliary battery and a battery isolator.

How a battery isolator works

The primary function of a battery isolator is to route DC current from a single power source to several batteries, while the batteries themselves remain unconnected. This is accomplished by connecting a single power source to multiple batteries with a switch wired so that only one battery is receiving power at any given time. There are many different types of power systems, switches and batteries that are used: from very simple systems that use a manual switch and two batteries, to very complex computer controllers quickly switching between any number of batteries. However, the most common type of battery isolator that most people encounter is in a car. In this type of situation the car’s alternator is wired to the car’s primary battery and also to an auxiliary battery that is dedicated to the starter. After the car’s engine is turned on, all power from the alternator is routed to the auxiliary battery, and a sensor is activated that monitors the auxiliary battery’s charge. Once it is full, an electrical switch is activated that reroutes the power back to the primary battery.

A battery isolator is a simple system, but is extremely useful. Adding a battery isolator to your vehicle, adds safety, convenience, and peace of mind – never get stranded again.