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How do you disconnect a car battery?

During the life of a car, it is almost inevitable that you will have to disconnect the battery at some point. Whether it be for simple car repairs or a major engine repair, knowing how to disconnect your battery will prove to be an extremely valuable skill.

Before you disconnect your car battery, make sure your car’s ignition is in the off position, remove your keys, and put on protective gloves and goggles. Now locate your hood release and open your car’s hood.

Be sure to secure your car’s hood before you begin working. Locate your car’s battery within the engine compartment. Once you have located the battery, use a socket wrench in the appropriate size to loosen the negative side of the terminal.

When you have completely loosened the negative terminal, you are able to remove it. Repeat this same process for the positive terminal. For more detailed instructions and tips for cleaning your battery, read ahead!

Safety First!

There are a few precautions that you must observe before disconnecting your battery.

Always turn your ignition off and remove the keys before beginning.
Use appropriate gloves and safety goggles at all times.
In addition to holding a potentially lethal electrical charge, your battery is also filled with all sorts of corrosive chemicals that have the potential to do some serious damage if you aren’t careful.

Terminal Location

Locate the negative terminal. It will either be labeled with a minus sign near the terminal and/or have a black connector cap. The positive terminal will be labeled with a plus sign near the terminal and/or have a red connector cap.

Determine the Socket Size

Always loosen and remove the negative terminal first when working with batteries. To determine the correct size socket you will be using, place the socket near but not on the negative terminal and visually compare the size of the bolt.

Attach the appropriate socket size to your wrench handle or extender and turn the bolt counterclockwise to loosen it. Once it is fully loosened, remove it and isolate it from the battery by securing it away from the battery with a zip tie or wrapping the terminal cable in a clean shop towel.

If you have any trouble loosening the terminal due to corrosion or the need for a special tool, please contact your local auto parts store or a trusted mechanic.

Positive Next

Now, follow the above directions for the positive terminal. Also be sure to isolate this cable by using a zip tie and/or clean, dry shop towel. If this cable comes into contact with any conductive surface, it could potentially cause electrical damage.


Now that you’ve safely disconnected and isolated both the negative and positive battery cables, you can now continue your work. If you are replacing your car’s battery, read ahead for additional steps.

After you remove both battery cables, look for the brackets that secure the battery to your engine compartment and loosen/remove any fasteners holding it down.

Slowly lift the battery straight up. Car batteries can sometimes weigh 40 pounds, so be mindful. Ask for help lifting, if needed.

Using an old toothbrush or wire brush, brush the connectors with a 25% baking soda/distilled water mixture until clean.

Once dry, you can begin the new battery installation.

Place the fresh battery in the battery tray and secure the fasteners.
Now, locate the positive terminal and connect it first.
Connect the negative terminal next.
Now, you should be ready to close your car’s hood and test your new battery install by starting your engine.

Battery Disposal:

Now that you have properly installed your new battery, it’s time to dispose of the old battery. The easiest way to dispose of an old battery is to return it to the store that you purchased the new battery from. Most auto parts retailers and dealerships are able to dispose of your old battery for a small fee.

Battery Disclaimer:

The batteries in hybrid vehicles can produce over 300 volts of potentially lethal charge. Whenever you need to work on any electrical part in your hybrid car, you must remember to completely disable the high-volt battery in the rear of your vehicle. In most hybrid vehicles, the wiring is specifically color-coded orange.

To reduce your risk of electrocution, use only tools and gloves that are insulated for use around electricity. Follow all procedures exactly per the manufacturer because there may be more steps involved in the removal of a hybrid battery.

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