How to Clean Battery Terminals

Alex Palmeri
January 27, 2017
Average Repair Cost & Time
Avg. Repair Time
20 minutes
Difficulty Level

Nobody wants to fall victim to a dead battery. Over time, the battery posts and terminals on a car will build up with a layer of corrosion. This build-up can mean problems for a car when a poor electrical connection develops between the battery cable and the battery. The battery can also develop cracks as a result of this corrosive build-up and emit hazardous and explosive gases. Cleaning the corrosion will prolong battery life and prevent these car battery problems.

Parts & Tools Required
  • Battery terminal cleaning tool
  • Wrench or socket set
  • Wire brush
  • Toothbrush
  • Rubber, latex, or nitrile gloves
  • Safety glasses or goggles
  • Baking soda
  • Bowl of water
  • Rags or towels
  • Optional: Battery terminal cleaner spray
  • Optional: Battery terminal protectant spray
Before You Begin

Prior to starting repairs, it is wise to follow a few basic safety precautions. A car battery contains lead and sulfuric acid. The acid can cause severe burns if leaking from a damaged battery. Flammable hydrogen-sulfide gases are also released gradually from the battery. Avoid touching the corrosion built up on the battery posts and terminals. Use personal protective equipment such as a pair of solvent-resistant gloves to protect your hands. Shield your eyes with safety glasses or goggles. Do not smoke while servicing a car battery. And be aware of anyone who might be in the area of your repairs.

Please read and understand this Legal Disclaimer.

Once you have ensured your safety you are ready to begin.

Repair Steps

Clean off any loose debris with a wire brush.

Remember, the battery contains lead and sulfuric acid. The corrosion is a byproduct of these and other compounds. Avoid touching or breathing the dust from this corrosion.

Mix a tablespoon of baking soda into one pint (2 cups) of water to form a cleaning solution. Using a toothbrush, scrub the terminal clamps and battery posts to remove any corrosion, dirt, and grime. Dry with a rag or towel to remove dirt, debris, and cleaning solution.

An alternative to the baking soda solution is to use battery terminal cleaner spray. In addition to cleaning and neutralizing acid and removing corrosion by-products, some sprays also include a dye to help detect leaks in the battery.

Use a wrench or ratchet and socket to loosen the terminal clamps. Carefully twist the clamps to remove them from the battery post. Remove the black negative (–) cable first, followed by the red positive (+) cable. Disconnecting the battery may lead to the loss of settings in the navigation and stereo systems, as well as possible loss of data stored in the vehicle’s computers which can adversely affect vehicle operation. (See the article Electrical Issues After Replacing the Battery for more information)

Use care when removing the terminal clamps from the battery posts. Excessive force can cause internal damage to the battery that may result in a short circuit.

Inspect the battery cables and terminal ends for signs of wear and corrosion. Also, inspect the battery and battery posts for damage. Replace any components as needed to prevent potential failure.

Using the cone-shaped end of the battery terminal cleaner, scrub the inside of the terminal clamp until it is clean, bare metal.

Some vehicles have terminals that screw into fittings on the side of the battery, rather than clamps that fit on posts. If this is the case, use a wire brush to clean the threaded studs.

Work the female end of the terminal cleaner onto the battery posts. Place the cleaner on each post and rotate back and forth until the posts are clean and bright in appearance.

Again, use the baking soda and water cleaning solution (or terminal cleaner spray) to clean the body of the battery. Remove any residual corrosion and grime with a towel or rag.

Starting with the positive (+) cable, reattach the terminal ends to the battery. Avoid excessive force and tighten the clamps until they are snug.

Finish the job by applying a coating of battery terminal protectant spray to help avoid corrosion in the future.

If you would like to learn how to safely jumpstart a car with a dead battery, see the article How to Jumpstart a Car.

Alex Palmeri

About the Author

Alex Palmeri worked nine years as a master technician at Mercedes-Benz of Chicago and is currently the foreman at a large fleet garage. He writes about automotive news, maintenance and racing, and runs a YouTube channel called Legit Street Cars.

1 User Comment

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By , March 07, 2017
As a side note, I've heard this only applies to gasoline powered cars and that hybrids should be left to the experts, especially as it relates to the battery. Do you agree?