Car batteries conserve a significant amount of energy and are designed to produce an electrical discharge in an instant. They need to be handled with care when you want to start a car with cables or work on its electrical system. If you need to disconnect a car battery, follow these steps.
Steps
Step 1. Take the necessary precautions before attempting to disconnect your battery
In addition to having a potentially lethal electrical charge, it contains corrosive agents that can produce a flammable gas. Therefore, before removing it, follow these tips.
- Turn off the car.
- Wear safety glasses and gloves to protect your hands and eyes.
Step 2. Find the negative terminal above the battery
It usually has a black cover. There may be a “minus (-)” sign next to the connector. The positive terminal usually has a red cover and a plus (+) sign next to the connector.
Step 3. Determine what wrench you need to loosen the negative terminal nut
Always work on the negative terminal first and then the positive terminal when disconnecting a battery.
- Take a wrench from your tools and hold it close to the negative battery terminal nut, but don't touch it. Visually assess which compass you need.
- Apply the correct compass to your key. You may need to use an extender to reach the nut.
- Put the wrench on the negative terminal nut and turn counterclockwise (remember: time is running out). It will only take a few turns to loosen it.
- Remove the negative connector from the battery after loosening the nut. Push it aside so it can't come into contact with the battery while you work.
- If the cable is tied to the battery, you may need to use a specific tool to remove it. Ask your trusted mechanic for information.
Step 4. Follow the same procedure to disconnect the positive terminal
After removing it, do not let it come into contact with any metal part of the car. There is a residual charge in the system, which if discharged onto a metal surface could break or damage the vehicle's circuits.
Step 5. Keep working
After disconnecting the battery cables, you can safely perform repairs on the vehicle's electrical components. If you just need to replace the old battery with a new one, you can do it in a few simple steps.
- After disconnecting the battery, unscrew the arms that hold it in place.
- Lift the battery straight up, out of its seat. Remember that it can weigh up to 20 kg, so ask someone for help if you need it.
- Using an old toothbrush, clean the battery housing and connecting cables with a diluted solution of baking soda. Let them dry before inserting the new battery.
- Put the new battery in its place and tighten the arms that hold it in place.
- Connect the positive terminal first, then the negative one. Remember to tighten the nuts on all sides.
- Close the hood and start the car.
- Recycle the old battery properly. As part of the service offered by the store where you bought the battery, the collection of the old one is probably also included. If not, take it to a garbage disposal center or workshop: these services often accept exhausted batteries for a small fee.
Advice
- Ordinary car batteries can generate several hundred amperes of current, roughly the same energy used by an arc welder. Do not test charging your battery by touching the positive and negative terminals with a metal tool. The current is so intense that it could damage the instrument and you!
- Tie the cables away from the battery as you work, to make sure they can't accidentally re-form the contacts.
- Remove all jewelry you wear, especially rings and necklaces.
- Work outdoors, where gases don't have a chance to thicken.
- Wear insulated gloves and protective eyewear.
- Hybrid car batteries have voltages in excess of 300 volts, which is potentially lethal. If you need to work on an electrical component of a hybrid car, start by deactivating the high voltage battery in the back of the car. The cables of that device are usually orange. Use insulated tools and gloves at this stage to reduce the risk of electrocution. Make sure you follow the manufacturer's recommended procedure to the letter, as additional steps may be required.
