Tools and Materials

Tools

Materials

New Car Battery
Battery Terminal/Post Grease or Spray
Battery Terminal Anti-Corrosion Pads or Washers
Cleaning Cloths

Note

Product costs, availability and item numbers may vary online or by market.

When Do You Need to Replace a Car Battery?

A car battery with blue, green and white corrosion around a terminal.

A new battery will give your car power for reliable starts in cold or hot weather, making driving much more convenient and reducing the risk that you’ll get stranded. It’s not uncommon for a car battery to run down and need a charge or jump-start if you leave your car’s lights on, but it’s not normal for a car battery to die with no apparent cause. So how do you know you need a new car battery? In general, if your car battery is more than three or four years old, it might be due for testing or replacement. Several factors, including the actual expected life span of the battery, temperature extremes, the electronics you use and how you drive — short trips versus long drives — can affect battery operation and life span. There are a few signs that may indicate you need a new battery.

Your car regularly fails to start or has difficulty starting, and jump-starting isn’t effective.
You need to regularly jump-start or charge the battery.
The battery shows signs of damage or seems to be swollen.
You don’t drive the vehicle often.

Your car may have a battery indicator that lets you know when there’s a problem with the electrical system. Keep in mind that this indicator, as well as the above signs — such as slow cranking and the need to jump or charge a car battery — can indicate other problems with the electrical system beyond a battery issue. Before purchasing a new battery, it’s a good idea to get your existing battery tested.

Caution

Check your car’s manual for instructions and safety precautions before attempting to jump-start or charge your car battery.

Tip

If you have a receipt for your existing battery, it’s a good idea to bring it with you when you purchase a new battery because it may contain warranty information that’ll be helpful. If possible, once you remove the existing battery, it’s a good idea to take it to an auto parts retailer. Many retailers offer battery disposal or recycling services.

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Replacing a Car Battery

In many cases, replacing a car battery is relatively simple. Before you begin, make sure you have a work area with good ventilation and good lighting. If necessary, set up work lights so you have a good view of the area.

If you’re not comfortable working on your car or replacing a car battery, leave the work to a professional repair facility or check with a local auto parts retailer. Many offer a replacement service with a battery purchase. Often, this will include disposal of the discharged battery.

Caution

We outline general steps below that show you how to replace a battery in a car. These steps show you how to replace a standard 12-volt battery in a conventional, gasoline-powered car. Always follow any specific instructions or safety procedures specified by your vehicle manufacturer.

Good to Know

On many cars, disconnecting the battery will erase presets in your audio, phone and other electronic systems, so plan on taking some time to restore them once the new battery is in place.

Instructions

Park the vehicle securely with the parking brake set. For an automatic transmission, leave the car in park. For a manual transmission, make sure the car is in first gear or reverse. See your manual for specifics before you begin replacing a battery. Car batteries may be located in different areas of the car depending on the manufacturer and model. While the battery is often readily visible at the front or back of the engine compartment, it may have a cover, or it could be in the trunk, under a rear seat, near a wheel well or in a compartment under the floor.

Let the engine cool before you begin work. Locate the battery cables and the positive and negative terminals. These are the clamps that connect to the posts on the battery. You’ll connect the negative terminal to the battery post that has a negative symbol (-) stamped or embossed on the battery casing next to it. The positive terminal will often have a red cover or an enclosure with a red positive (+) symbol, and you’ll connect it to the post that’s next to a positive symbol on the battery.

Caution

Wear eye protection and nitrile or latex gloves when working with a battery. It’s also a good idea to wear long pants, a long-sleeve shirt, and closed-toe shoes or work boots.

A person in blue gloves using a wrench to loosen the bolt on a negative car battery terminal.

There’s usually a nut and bolt clamping the terminals to the battery posts. Using a combination wrench or a ratchet and socket, loosen the negative terminal and pull it away from the post. If there’s a significant amount of corrosion around the terminal, you may need to carefully clean it away with a wire brush before you can reach the fasteners. If you can’t move the terminals, you may need a tool known as a terminal puller to disconnect them. The terminal puller clamps around the terminal and rests on the battery post. As you screw the handle down, it raises the terminal up along the post.

Caution

Don’t allow any metal or other conductive material to connect the two battery posts or to simultaneously touch the positive battery post and the car body or frame.

Tip

Keep a good grip on fasteners and hardware as you remove them and put them in a secure place. It can be difficult to locate a nut or bolt if it falls, particularly if you’re working in the engine compartment.

A magnetic pickup tool with a telescoping handle can help you recover dropped fasteners quickly and easily.

A car battery usually has a device that secures it to the battery tray or enclosure to keep it from moving during operation. Remove the retaining device and lift the battery out of the battery tray. Some batteries have a strap to help you move them. Be careful. A car battery is heavy, and you need to avoid tipping or jarring it to prevent spilling any of the acid it contains. Place the battery upright in a safe location, out of reach of children and pets.

A person in blue gloves using a terminal brush to clean the positive terminal on a car battery.

Check the cables and terminals. If you notice damage, you’ll need to get them replaced by a professional. Clean the terminals to remove any buildup or corrosion. A specialized battery-terminal brush designed to fit into the terminal sockets and over the battery posts will help you clean the terminals, but a small wire brush will work to clean them as well. While the battery is out, it’s a good time to brush out any leaves or other debris from the battery tray.

Carefully place the new battery in the tray and make sure to align the positive and negative posts with the positive and negative terminals. Once you’ve oriented the battery correctly, reinstall the retention hardware. The new battery will likely have plastic caps covering the terminals. Remove and place them over the posts of the discharged battery or dispose of them.

Install the anti-corrosion washers over the posts on the new battery — red for the positive post and green or black for the negative post. Apply a small amount of anti-corrosion grease or spray to the battery posts and terminals. Lithium grease and dielectric grease can work for this application, but check the instructions to make sure they’re labeled for this use. The washers and grease will help reduce buildup that can prevent a good connection between the terminals and battery posts. A battery with a poor connection won’t charge efficiently while the vehicle is operating.

Caution

Remember to keep any conductive material from touching both battery posts or touching the positive post and the car.

Place the negative terminal over the negative battery post and tighten it. Check that you’ve securely connected the terminals to the posts so that they won’t shift. Make sure you’ve secured the battery in the tray to prevent it from moving. If the battery compartment has a cover, put it back in place. Start the car to confirm the battery is working correctly.

Tip

Save the receipt for your new battery in a safe location where you can find it easily. If you ever have problems with the battery, any registration or warranty information included on the receipt will be useful.

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