How to Install a Battery Isolator

A battery isolator allows you to attach two or more batteries to the same charger. Without a battery isolator, batteries at a higher level of charge discharge into batteries at a lower level of charge. Rapid discharge can cause damage to batteries or even cause a fire, so it is important that you install an isolator correctly.

1. First: Finding the right battery isolator

   Before you purchase a battery isolator, it is important to determine the rate of electrical current that it needs to conduct. You need to find both charging current and discharging current. You can find the maximum charging current by looking at the current produced by your charger or alternator. Then, find the maximum discharge rate by looking at the power consumption of all devices connected to the batteries. This is done by looking at the current rating of the fuses or circuit breakers. The sum of the maximum charge rate and maximum discharge rate gives you the current rating of the isolator.

2. Second: Installing the battery isolator

   Installation itself is a relatively simple process. You need to connect the charger to each of the batteries individually, and you need to make sure that none of the dependent circuits overlap. To maximize charge rate, place the isolator as close to the batteries as possible, and minimize the length of electrical wires connecting them. In an automotive setup, ensure that the negative terminals of the isolator and all batteries are properly grounded.

3. Third: Testing the battery isolator

   After you are done installing the isolator, it is important to test the installation for faults. Connect a fully charged battery to each circuit. Test each circuit individually to ensure that it is able to supply sufficient power. After this test is complete, connect a dead battery, and monitor its temperature. If it quickly grows warm, disconnect it immediately, as a current leak may exist from the live battery. Then, recheck your wiring.