What’s a Battery Isolator?

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A battery isolator splits DC current, allowing it to flow in one direction from the device to multiple batteries. It prevents one battery from discharging others and allows for charging multiple batteries from one alternator. It’s useful for vehicles with multiple batteries and devices that draw significant energy. The main disadvantage is that charging time can increase when multiple batteries are charged.

A battery isolator is a type of electrical device that splits DC current and allows current to flow in only one direction, from the device itself to any number of batteries that may be connected to it. It’s a common device in vehicles that have more than one battery, such as recreational vehicles (RVs), which may use one battery for starting the engine and driving tasks, but another battery for household appliances and other devices. Using a battery isolator allows you to charge multiple batteries from one alternator, but prevents one battery from discharging the others when it is discharged. It also has the ability to fully charge batteries based on the need for each battery.

Vehicles or with multiple batteries connected to the same electrical system can greatly benefit from the addition of a battery switch. Without such a device, when one battery is discharged, it can discharge other batteries in the system. A battery isolator allows batteries to be connected to a system without the risk of discharging each other. For example, utility vehicles such as tow trucks with a separate battery for the winch and other systems can use those systems without worrying about them draining the battery used to start the vehicle.

The battery used to jump start the vehicle is the most important, although there are more batteries that support other functions. If the vehicle cannot be started, neither of the batteries can be charged because the vehicle’s alternator charges them and only works when the vehicle is in motion. Any vehicle with a battery isolator installed can always charge its other batteries as long as there is enough power to start the vehicle.

Other benefits of having a battery isolator include the ability to use any of the batteries to jump start the vehicle if needed. Some isolators are also switchable and allow the batteries to run on the same circuit to increase cranking power if desired. Any vehicle that uses devices or systems that draw a significant amount of energy can benefit from a battery isolator. The main disadvantage of most types of isolators is that the current from the alternator is split between the batteries, so when multiple batteries are charged, the charging time can increase.

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