How to Change a Car Battery Like a Pro

Discover how to take care of this simple DIY automotive repair and keep more money in your wallet.

By Timothy Dale | Updated Nov 24, 2021 1:00 PM

how to change a car battery

Photo: istockphoto.com

One of the standard automotive repairs that needs to be completed on a semi-regular basis is replacing the car battery. Learning how to replace a car battery doesn’t have to be difficult, though some DIYers might hesitate to take on this task because of the potential danger involved with figuring out how to install a car battery.

When you are first learning how to connect a car battery, make sure to go very slowly so that you know the correct order in which you should disconnect and reconnect the positive and negative cables. Otherwise, you could cause damage to the vehicle or yourself.

Typically, a car battery needs to be replaced about once every 3 years, though there are clear signs to watch for that might indicate the need to replace it sooner. For example, you might notice your headlights dimming on their own or the car struggling to start in colder weather. If any of these symptoms occur, then it may be time to learn how to remove a car battery and replace it with a new, compatible battery.

BEFORE YOU BEGIN

Before even thinking about removing a car battery or trying to figure out how to reconnect a car battery, step back and consider the possible dangers. Car batteries are powerful electrical devices that can cause significant damage to the vehicle or cause severe injury to the DIYer if this repair is not handled carefully. Make sure to take proper safety precautions and follow these steps in the indicated order to avoid harm.

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STEP 1: Find suitable parking and turn off the vehicle.

Typically, when you work on a vehicle it’s a good idea to park on a level surface in an area that is relatively private and secure, like your garage, a level driveway, or even on the side of the road in front of your home. Once you find an appropriate place to work on the vehicle, put it in park and turn the vehicle off.

Remove the keys from the ignition to ensure that no power is going to the battery. Also, keep in mind that when you remove the battery, this will likely reset the clock, radio, navigation system, and alarm settings, so you will need to reset these auxiliary features after the repair.

how to change a car battery

Photo: istockphoto.com

STEP 2: Put on safety gear and locate the battery.

To help stay safe during this automotive repair, put on safety glasses and work gloves that are insulated against electricity. Make sure to remove any metal jewelry that could come in contact with the battery, like a watch, ring, or bracelet. These items could complete a circuit between the negative and positive terminals, resulting in the metal sparking, heating up, and possibly melting on your skin. These severe burns are no joke and will require medical treatment, so avoid the problem entirely and ditch the metal accessories.

Pop the hood or the vehicle’s trunk, depending on whether the battery is installed in the front or back of the car. If you don’t know what a car battery looks like, it is essentially a large, rectangular box that has two electrical cables connected to metal terminals on the top of the battery. Some newer vehicles might have a plastic cover over the battery, but you can remove it to gain access to the battery terminals.

STEP 3: Disconnect the negative cable.

The negative battery terminal is usually black and may have a minus (-) sign to indicate that it is the negative terminal. If applicable, remove the plastic cover on the battery and locate the black negative terminal cable. This cable always needs to be the first cable removed and the last put back on to help avoid the risk of completing a circuit between the two terminals and causing the battery to spark, short circuit, or melt down.

Use a compatible socket wrench to loosen the nut holding the negative cable in place and slide the cable off of the battery terminal. Keep the cable away from the battery, the positive cable, and any metal by securing it to the engine bay with a cable clamp.

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STEP 4: Disconnect the positive cable.

With the negative cable safely secured and out of the way, locate the red positive cable. The terminal may be marked with a plus (+) sign to help differentiate between the negative and positive cables. Loosen the nut holding the positive cable in place and slide the cable off of the positive terminal. Secure the cable to the engine bay with a cable clamp, ensuring that it does not come into contact with the battery, the negative cable, or any metal.

how to change a car battery

Photo: istockphoto.com

STEP 5: Remove the old battery.

The battery is usually held in place with multiple connectors to prevent it from moving or shifting while you drive. Use a socket wrench with an extension bar to loosen these connections and lift the battery out of the battery bracket. Keep in mind that a car battery can weigh more than 20 pounds, so you might need a hand to lift it out.

You might be able to trade the old battery in at your local automotive parts store. If the store won’t take the old battery, then you need to take it to a recycling center for proper disposal. Do not throw the old battery into the garbage. The chemical components can leak, causing damage to anything or anyone that comes in contact with the battery.

STEP 6: Install the new battery.

Make sure that you get the correct replacement battery by recording the year, make, model, and engine size of your vehicle and taking this information to your local automotive parts retailer. If you get the wrong battery, then it may be too big or too small for the battery bracket, making reinstallation impossible.

Put the new battery into the battery bracket. Use your socket wrench to secure the battery to the bracket so that it will not shift, tip, or otherwise move when you are driving.

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STEP 7: Connect the positive cable.

Grease the battery terminals with white lithium grease to prevent corrosion, then locate the red positive cable that you had previously secured to the engine bay with a cable clamp. Release the cable clamp and slide the positive cable onto the red positive terminal that may be marked with a plus (+) sign. Take your time.

how to change a car battery

Photo: istockphoto.com

Make sure that you are putting the correct cable onto the correct terminal. Secure the cable to the terminal with a socket wrench and double-check that you have connected the right cable. If the car battery is connected backward, it will send the electrical current back through the car systems. Your vehicle might have a fuse that is designed to protect your engine from this sort of mishap, but it is better to take no chance. The charge can cause significant damage to the vehicle.

STEP 8: Connect the negative cable.

The negative battery terminal is usually black and may be marked with a minus (-) sign to help distinguish it from the positive terminal. Grease the battery terminal and release the black negative cable from the cable clamp. Slide the black negative cable onto the black negative terminal.

Double-check to ensure that you are connecting the right cable to the right terminal in the correct order. If the negative cable is connected first, there is a higher risk that the socket wrench could complete the circuit between the negative and positive terminals when connecting the positive cable, resulting in sparks, extreme heat, and molten metal that could be flung toward you.

STEP 9: Start the vehicle to test the repair.

how to change a car battery

Photo: istockphoto.com

Once you have successfully reconnected the cables in the correct order and orientation you can put the plastic cover back over the battery, if applicable. Clean up any tools that you used during the process, then close the hood and hop in the vehicle. The car should start up without a problem, though you will likely need to reset the clock, radio, navigation system, and alarm settings.

Take precautions when replacing a car battery to avoid harm.

Car batteries are powerful objects that have the potential to harm you and your vehicle in a number of ways, including burning, electrocution, and corrosion. To help prevent injury, make sure to install the battery in the correct orientation and avoid working in the snow, sleet, or rain. Note also that replacing a hybrid or electric car battery is not typically a DIY job because these batteries have a dangerously high voltage and can be difficult to access, remove, and reinstall due to a greater degree of complexity in the hybrid and electric vehicle designs. If you have one of these eco-friendly vehicles, it’s advised to have the battery replaced by a professional mechanic to avoid future problems with the vehicle.

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