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Car battery replacement is a must-do automotive maintenance task that needs to be completed on a semi-regular basis. If you just bought your first vehicle or want to brush up to avoid getting stuck on the roadside, knowing how to change a car battery is a valuable and easy skill to pick up on.
How to Know if a Car Battery Needs to Be Replaced
Before performing a DIY car battery installation, you may save time and money by first determining if your car’s battery needs to be changed in the first place. How long does a car battery last, though? Most need to be replaced about once every 3 years, but some car batteries may need to be changed sooner. If you’re struggling to start your car in cold weather, its lights are dim when idle, or the dashboard battery light turns on, then it may be time to learn how to disconnect a car battery and replace it with a new, compatible battery.
Tools & Materials
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Project Overview
Working Time: 1 hour
Total Time: 1 hour
Skill Level: Beginner
Estimated Cost: $80 to $200 or more, depending on the battery
Before You Begin
A car battery is a powerful electrical device that can severely damage a vehicle and injure a person if it is not handled carefully. Vehicle batteries are also moderately heavy, so some people may need assistance to remove and lift one out of a car. Make sure to follow all safety precautions and steps below in the order indicated to avoid harm.
Replacing a hybrid or electric car battery is not typically a DIY job. If you have one of these eco-friendly vehicles, have the battery replaced by a professional mechanic.
STEP 1: Park the vehicle on level ground.
Park your car on a level surface. Ideally this spot is in a private and secure area, like your driveway, garage, or—in a pinch—a parking lot or roadside. Make sure the vehicle is in park, engage the handbrake, and turn the vehicle off. Remove the keys from the ignition to ensure that no power is going to the battery.
Note that when you remove the battery, it will likely reset the clock, radio, navigation system, and alarm settings, so these may need to be reset after following the steps on how to install a car battery further below.
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STEP 2: Put on safety gear and locate the battery.
Wearing safety glasses and electrical insulated gloves is recommended when handling a vehicle battery, whether it’s being jump-started or replaced. Remove any metal jewelry that could come in contact with the battery terminals, such as watches, rings, or bracelets.
Depending on whether the battery is located in the front or back of the vehicle, open the hood or trunk. Look for a large, rectangular box with two 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 access the battery terminals.
STEP 3: Disconnect the negative cable.
The negative battery terminal is usually black and may be identified by a minus (-) sign on the car battery. If applicable, remove the plastic battery cover from the battery and locate the black negative terminal cable. The negative cable always needs to be disconnected first and reconnected last to avoid sparking, short circuits, or melting.
Use a compatible socket wrench to loosen the nut holding the negative cable in place. Slide the cable off of the negative terminal. Secure the cable to the engine bay with a cable clamp to keep it away from the battery, the positive cable, and metal surfaces.
STEP 4: Disconnect the positive cable.
With the negative cable safely disconnected and secured, locate the red positive cable. The connector will likely be covered by a red plastic cap, and the terminal may be marked with a plus (+) sign. 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, avoiding any contact with the battery, negative cable, or metal surfaces.
STEP 5: Remove the old car battery.
The car 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. Something to note about how to remove a car battery that sometimes goes overlooked is that car batteries can weigh 20 pounds or more, so you might need help to lift it out.
Once the old vehicle battery has been removed, set it aside in a safe spot for proper disposal. Do not throw it into the garbage or store it in or around your home.
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STEP 6: Install the new car battery.
Record your vehicle’s year, make, model, and engine size to ensure you buy the right kind of replacement car battery. The wrong battery may be too big or too small for the battery bracket, making reinstallation impossible.
Lower the new car battery into the battery bracket. Use a socket wrench to secure the battery to the bracket so that it will not shift, tip, or otherwise move while driving.
STEP 7: Grease the terminals and connect the positive cable.
If you notice any corrosion on ends of the battery cables before reconnecting them to the new battery, use a small amount of a baking soda-and-water mixture and an old toothbrush to clean them. Dry them with shop towels or cleaning cloths. To prevent future corrosion, grease both battery terminals with white lithium grease.
Release the red positive cable from its cable clamp and slide the positive cable onto the red positive terminal. Secure the positive cable to the positive terminal with a socket wrench and double-check that you have connected the correct cable to the correct terminal.
STEP 8: Connect the negative cable.
Release the black negative cable from the cable clamp and slide it onto the black negative terminal. Double-check that you are connecting the correct cable to the correct terminal—and in the correct order. If the negative cable is connected first, the socket wrench could complete the circuit between the negative and positive terminals when connecting the positive cable, potentially resulting in sparks, extreme heat, and molten metal being flung toward you.
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STEP 9: Start the vehicle.
After successfully reconnecting the cables in the right order, put the plastic cover back over the battery (if applicable). Remove all tools and cable clamps from the work area, close the hood, and start the vehicle. If the car starts up without issue, you may need to reset the clock, radio, navigation system, and/or alarm settings.
If the car doesn’t start, turn it off and double-check that the battery cables are connected to the right terminals and that the car battery is compatible with your vehicle. If the car continues to not start, it’s time to call a certified auto mechanic.
What to Do With an Old Car Battery
As with other types of battery disposal methods, you should never throw a car battery out with the regular trash. Its chemical components can leak, damaging anything or injuring anyone it touches. Local auto parts stores may offer free car battery recycling or a battery exchange program, in which you receive a gift card or store credit for bringing in old car batteries.
Another proper car battery disposal method is to drop it off at the nearest recycling center that accepts them. Call ahead to check that they’ll take it off of your hands, and to get instructions on safe transport and handling.
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Final Thoughts
Learning how to change a car battery yourself isn’t complicated, but it’s important to keep in mind that these batteries have the potential to damage your vehicle and harm you. To minimize these risks, be sure to turn off your vehicle before you begin, wear electrical-insulating gloves and safety glasses. You also want to avoid battery cable contact with the opposite cable, the battery, or metal surfaces, and be extra careful to disconnect and install the battery cables in the correct order.