How to Connect a Battery Isolator

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How to Connect a Battery Isolator

Battery isolators are useful equipment for vehicles with multi-battery systems. Such vehicles can include large vehicles, such as boats, trucks, and caravans, or standard sedan and coupe cars with powerful sound systems that run while the car's engine is off. Having additional battery power helps ensure that the vehicle can properly start and run. No matter what the context, battery isolators make certain that each of the vehicle's batteries are charged from the vehicle's alternator.


Equipment Needed to Install and Connect a Battery Isolator

Connecting a battery isolator is relatively simple, but before attempting the task, DIY mechanics should assemble the necessary materials. Planning ahead can help to ensure that the project runs smoothly. A few accessories are necessary to the safe and secure installation of a battery isolator.

Red and Black Cables

The red and black cables are wires insulated with a colored plastic coating. The red wire directs the electrical flow between the battery and the isolator. The black cable, on the other hand, grounds the isolator to the vehicle. A set of each is necessary to install the isolator properly.


Terminals are rings that have plastic screws along with them. They provide connection points for the red and the black cables. They terminals help to shuttle power between the battery and the isolator. If the terminals have worn away or have corrosion, they should be replaced with new ones.


Often labelled with "on" and "off" for ease of installation, the switch turns the isolator off if needed. Sometimes this is called a kill switch or a master switch. They are available in a variety of styles, and can even different sizes.

Other Equipment

Other items can help with installing a battery isolator, such as zip ties, wire lugs, and electrical tape. Wrenches and soldering irons can also prove helpful. In some cases, buyers may find everything that they need in one kit. This helps DIY mechanics install their new battery isolator without having to run out for additional parts.


Connecting the Isolator

Once the consumer purchases the auxiliary battery and all of the necessary equipment for isolator installation, the isolator is ready to install. Suitable locations for both installations include space under the vehicle's main bonnet or in a less crowded area, such as a car's boot. Installation techniques may differ for different brands and types of isolators (solenoid or diode-based), so DIY mechanics should make sure they know what they are working with before installation begins.

It is important to follow any installation instructions provided by the manufacturer exactly. Most isolator installation instructions require grounding the auxiliary battery or the isolator (or both) to the vehicle. Use the red cables to connect positive terminals on the main battery to the isolator, the alternator, and the vehicle's electrical system, while the positive terminals on the auxiliary battery are connected to the isolator and the additional appliances, such as a sound system, that are to be run off of the additional battery.


How to Buy a Battery Isolator on eBay

Experienced mechanics may have all of the additional accessories necessary to install a battery isolator and simply need to purchase the isolator itself. For those shoppers who do not have all of the additional equipment necessary to connect the isolator to the battery and secure all of the connection cables, reliable sellers on eBay offer kits that include all of the necessary installation equipment. Either way, shopping on eBay provides you with the opportunity to purchase the equipment you need to complete a multi-battery setup.

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