Regardless of how many batteries are available, the current flow from one battery to another will continue until all batteries in the electrical system reach the same charge level and may prevent the engine from starting.Ī battery isolator can eliminate the problem of battery drain all together. The current in the fully charged battery will drain to the less-charged battery, until both reach a common lower charge level, or even worse, discharge completely. This arrangement can present a problem when a fully charged battery is connected to a partially discharged or dead battery. Many 12-volt electrical systems rely on at least one battery to start the engine and another to power accessories. Generally built with diodes, isolators ensure that charge is evenly distributed between multiple batteries and the alternator. Despite seeming very similar, however, they function in different ways.īattery isolators are best seen as the distribution point of an automotive electrical system. Managing multiple batteries is where battery isolators and separators come into play. However, simply wiring extra batteries into a vehicle’s electrical system can allow auxiliary batteries to drain power from the main battery, inhibiting engine starting and other essential functions. For these applications, having a multiple battery system is essential. The addition of electrical loads such as lights, entertainment systems, communications equipment and other accessories continue to draw power when the engine is off. However, this requires balancing the needs of the battery against those of the electrical system. Controlling parasitic loads (battery drain) and properly distributing electrical power is crucial to keeping vehicles working.

Diode battery isolator