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How to Clean Battery Terminals in Your Car: The 6 Step Process

car battery

Clean battery terminals can keep your car from stalling at the most inopportune time. Even though the car battery is usually tucked away safely from the elements, the battery itself can be the source of corrosive hydrogen sulfide gas that eats away at the connections. Over time battery terminal corrosion weakens the electrical connection between the battery posts and the battery cables. Knowing how to clean battery terminals and the connection points will free them of residue and keep your car running. Here’s how to clean battery terminals in six steps.

1. Locate the Battery

Most car batteries are located underneath the hood and are on the left or right side of the engine bay. With some models, such as in the Chevrolet Cobalt, Hyundai Sonata Hybrid and the BMW 5 Series, the battery is located in the trunk. Other vehicles like the Grand Cherokee, Audi A7, Ford Transit, or Mercedes ML the battery is located under one of the front seats. Cadillac, Oldsmobile and Mercedes have also located batteries under the rear seat. Dodge vehicles even place the battery behind the front wheel inner fender liner by the front bumper. Older model Corvette owners may have to remove a fender panel to find the battery. If you can’t find your battery, consult your owner’s manual. Once you locate the battery you may need to remove a cover or shield depending on where it is located. You will need to have complete access to the area where the battery cables connect to the battery, either on top or on the side of the battery.

2. Lift the Terminal Covers

Plastic or rubber covers protect most batteries and must be removed to access the clamps that connect the cables to the terminals. Be careful with the terminal covers as they may be delicate from age and heat. In some cases a build up of residue, identified as a white powder, may need to be cleared away with a paper towel or clean shop rag. Don’t forget to put on a pair of work gloves and don your safety glasses. While the likelihood of of something bad happening is low with this project, it is always good to be protected.

3. Disconnect the Car Battery

Each clamp or bolt fastened to the terminals must be disconnected for the cleaning to be effective. You will do this by loosening the negative clamp or bolt first, followed by the positive clamp. For top post batteries the battery cable clamps are commonly held on via bolts and nuts. Side post batteries are commonly held on via a single bolt through each battery cable connection. If excess corrosion is present, you may need to use metal pliers to disconnect the terminal from the battery post. If the terminal is really stuck, you may need to try a special tool called a battery terminal puller. While working on the battery, avoid touching other metal objects, such as the frame of the car, otherwise you risk shorting out the battery. Be aware of your work area. If necessary wrap electrical tape around the end of any tools you are using to work on the battery connections to reduce the risk of a short.

4. Choose Your Cleaning Agent

Clamps as you would find with a car battery.

When it comes to cleaning the car battery, you have a choice of two easy to source cleaning agents. The most common one is plain old baking soda. Here, you will mix two tablespoons of baking soda with an equal amount of water in a clean container. Stir the solution to form a paste, then use a toothbrush (or similar plastic bristle brush) to apply the paste to each terminal. The solution will begin to sizzle as it interacts with the corrosion. Use a wire brush to remove the remaining residue. Alternately, you can use a cola product to clean the terminal. Simply obtain one new, 12-ounce can. Then, evenly pour the entire contents directly on the battery terminals to get the job done. The advantage here is that you don’t need to make a paste. Just follow up with the wire brush, if necessary. We suggest picking your cleaning agent based on how hard it will be to remove afterwards. You likely don’t want to use the cola method if the battery is located inside the car interior.

5. Rinse and Dry

With the terminals now nearly free of residue, you’ll need to remove the paste or soda to finish cleaning. A spray bottle containing water will do; simply wash each terminal to remove the dregs with paper towels or clean shop rags. Resist the temptation to grab the garden hose and give everything a good blast. Use just enough water to clean things up and not push water into places that could cause a problem. Then, use a rag and dry each terminal. Lastly, spray battery terminal protector on each post to curtail future corrosion.

6. Reconnect the Clamps

Connect the positive battery cable clamp or bolt first, followed by the negative battery cable clamp or bolt. However, if you notice residue on the connections, clean it off before reattaching. Use a wrench to tighten as needed. Lastly, put the rubber or plastic covers over each junction. If you removed any access panels or covers you can put them back on now. Your work is done, the battery is clean and you’re ready to put your tools, cleaning agents and gloves away.

Maintaining your car’s battery should help keep it in sound working condition until it’s ready to be replaced. The average life of a car battery is about four years, therefore it should be tested with a multimeter on occasion. Hot weather is its biggest enemy and will degrade a battery faster.

Check out all of the batteries available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on how to clean battery terminals, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photo courtesy of Flickr.

Matthew C. Keegan View All

Matt Keegan has maintained his love for cars ever since his father taught him kicking tires can be one way to uncover a problem with a vehicle’s suspension system. He since moved on to learn a few things about coefficient of drag, G-forces, toe-heel shifting, and how to work the crazy infotainment system in some random weekly driver. Matt is a member of the Washington Automotive Press Association and is a contributor to various print and online media sources.

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