How to Clean Corroded Car Battery Terminals

(Updated on April 14, 2021)

The car battery is essential to sustain the functionality of the vehicle. Whenever you attempt to start your car, an electrical current is sent from the battery to the starter motor. This is how the engine turns on and runs. As for the other electrical components of the vehicle, the alternator supplies the power to run them. However, this cannot happen if the car battery is damaged, low on power, or corroded.

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When you connect battery cables to the car battery, you connect through to something called battery terminals. These are made of heavy-duty metal with very little electrical resistance. When you lift the hood of your vehicle and check the battery terminals, you’ll want them to remain clean. If you happen to see the terminals covered with corrosion or other grime, then you need to remove the corrosion at once.

Corrosion forms on battery terminals when hydrogen gas emits from the battery acids and hits the outside atmosphere. It usually takes a few years before you start seeing this happening on your terminals, depending on how often you drive your vehicle. Hot temperature and summer months can also speed along this process of corrosion on the terminals.

If the negative terminal is covered in corrosion, then your vehicle is probably not being charged enough. That is when you’ll experience all kinds of electrical problems, such as difficulty starting the vehicle or problems with your electrical devices in the vehicle. It is best to periodically check your terminals for any signs of corrosion. Just the smallest amount of corrosion means that your battery is starting to wear down. That doesn’t necessarily mean you need a new battery. It just means you need to clean your terminals so that you can sustain an electrical charge for however long the battery stays alive.

Cleaning Corrosion Off a Car Battery

When you begin the cleaning process, the first step is to disconnect the cables from the car battery terminals. Make sure your vehicle has been turned off for a couple of hours beforehand. This will help ensure that there won’t be any power spikes. Also, take note of how the battery is configured inside the vehicle. Are the terminals on the side or top of the battery? If they’re on the side, then the cable nuts can be loosened with a 5/16” socket wrench. If they’re on top, then you need a 3/8” socket wrench. Start with the negative terminal by disconnecting its cable first.

Inspect the battery to ensure it is not damaged or cracked. If it looks like it’s leaking, then you need to replace the battery and clean the terminals. The best way to remove corrosion from the clamps and cables is to dip them in a bowl of hot water and baking soda. Find a toothbrush that is no longer used and dip the bristles into the mixture. Use the toothbrush to scrub off the corrosion from the terminals and battery. There are special terminal cleaner brushes available at auto stores too.

Once all the scrubbing and dipping is done, use a clean disposable rag to dry the cables, terminals, battery, and clamps. Now reattach the clamps to the terminals. This time, you’ll start with the positive terminal first and then move onto the negative terminal. After you’ve reattached them, apply some petroleum jelly to the terminals. This will stop any new corrosion from forming for a long time. A better alternative to petroleum jelly is special anticorrosion grease that is available in auto parts stores.

It is not that hard to clean battery terminals. The hardest part is removing the cables and clamps from the battery. The rest is easy after that.

2 thoughts on “How to Clean Corroded Car Battery Terminals”

  1. Good article.
    In the first line of “Cleaning Corrosion Off a Car Battery”, I think what you meant to say is “the first step is to disconnect the cables from the battery terminals”.


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