How to Ground a Car Battery

by Edwin Thomas
Kristopher L Crump/Demand Media

Grounding is a fundamental safety feature in any electrical circuit, but establishing a good ground in a car battery is vital because their lead-acid design is tailor-made to deliver a huge jolt of electricity. Grounding mistakes with car batteries can cause hazardous electrical contacts or even battery explosions. Whether they know it or not, most people who own a car already know how to ground a car battery because they know how to jump-start the battery. Similar principles can be used to create a more permanent grounding capability, such as might be used at a charging station.

Jumper Cable Grounding

Step 1

Put the red connector on the red, positive post of the dead battery.

Step 2

Clamp the other end of the red cable to the positive post on the live battery.

Step 3

Connect the black connector to the black, negative post of the live battery.

Ground the connection between the batteries by clamping the negative connector to an unpainted metal part of the car with the dead battery, such as a nut or bolt on the engine or surrounding compartment.

Permanent Grounding Station

Step 1

Drive a metal rod, such as a piece of steel rebar, into the ground with a hammer.

Step 2

Clamp one end of a battery cable around the metal rod, and tighten the cable clamp's nut with a pair of insulated pliers or an insulated wrench. This is now your negative cable.

Step 3

Connect the positive cable of the deactivated charger to the positive post of the battery.

Ground the battery by putting the clamp on the other end of the negative battery cable onto the negative post of the battery. Fasten the clamp by tightening its nut with the insulated pliers/wrench.

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