Disconnect a Car Battery
A car battery is a rechargeable battery that supplies electric energy to an automobile. If you need to disconnect your car's battery to make certain repairs, read this article to learn how.
Contents
10 Second Summary
1. Turn off the ignition.
2. Put on a pair of safety goggles and gloves.
3. Use a socket to loosen the nut on the negative terminal.
4. Remove the positive terminal.
5. Perform any necessary repair work.
Steps
- Take the necessary precautions before you try to disconnect your battery. Besides holding a potentially lethal electrical charge, batteries contain corrosive agents that can produce a flammable gas. Before you remove your car's battery, take these safety steps.
- Turn off the ignition.
- Wear safety goggles and gloves to protect your eyes and hands.
- Find the negative terminal on the top of your car's battery. It usually has a black cover. The battery itself may have a minus sign near the connector post. The positive terminal usually has a red cap or a plus sign on the battery near its connection post.
- Determine what size socket you need to loosen the nut on the negative terminal. Always work on the negative terminal before the positive when you disconnect your battery.
- Grab a socket from your socket kit and hold it near, but not against, the nut on the negative terminal of your battery. Ascertain visually the socket size you'll need to loosen the nut.
- Put the appropriately sized socket on your wrench. You might have to attach a wrench extender to reach the nut.
- Put the wrench on the nut on the negative terminal and turn counterclockwise (remember: righty tighty, lefty loosey). It will take only a few turns to loosen it.
- Pull the negative connector from the battery after you've loosened the nut. Push it aside so it is unable to make contact with the battery while you're doing your work.
- If the cable is seized to the battery post, a special battery cable removal tool may be needed to remove the negative connector. Ask your local auto parts store or mechanic.
- Follow the same procedure to disconnect the positive terminal. After removing it from the terminal, don't let the positive connector touch any metal part of the car. There is residual current in the system that, if it were to touch a metal surface, could disrupt or damage the circuits in the vehicle.
- Continue with your work. With the battery cables disconnected, you can safely perform repairs on electrical components of the vehicle. If you just need to put in a new car battery, it can be done in a few simple steps.
- After the battery is disconnected, unscrew the brackets that hold it in its tray.
- Lift the battery straight up, out of its tray. Keep in mind that car batteries can weigh 40 lbs. so ask for help if you need it.
- Using an old toothbrush, brush the tray and battery cables with a diluted baking-soda mixture and allow them to dry before putting in your new car battery.
- Place the new battery on the tray and tighten the clamps.
- Connect the cable for the positive terminal first, then the negative. Remember to securely tighten the nuts on each.
- Close the hood and start the car.
- Dispose of the old battery properly. The auto-parts store you bought your new battery from probably will take the old one as part of its service arrangement. If not, take it to a recycling center or automotive garage. Most accept old batteries for a nominal fee.
Tips
- Standard car batteries can generate several hundred amps of current, which is roughly the amount of current used by a welding arc. Do not try to test your battery's charge by touching the positive and negative terminals with a metal tool. The current is so high it could damage the tool and potentially harm you, as well.
- Zip tie the cables away from the battery to prevent cables from returning to the battery terminal and causing sparks or electrocution.
- Remove all jewelry, particularly rings and necklaces.
- Work outside, where gases have no chance to build up.
- Put on protective eyewear and insulated gloves.
- Batteries in hybrid vehicles produce more than 300 volts, which is a potentially lethal level. If you need to work on any electrical component in a hybrid vehicle, disable the high-voltage battery in the back of the car first. The wiring is usually color-coded in orange. Use insulated tools and gloves when performing the task to reduce the risk of shock. Be sure to follow the exact procedure from the manufacturer on disconnecting a hybrid battery as there may be additional steps involved.
Things You'll Need
- Socket-wrench set
- Socket-wrench extender
- Protective eyewear
- Insulated work gloves
- Old toothbrush
- Small pan
- Baking soda
- Water
- Zip ties
