How to Clean Corroded Car Battery Terminals (Without Removing)

Co-authored by Duston Maynes

Last Updated: March 9, 2024 Approved

Many drivers experience difficulty starting their vehicles at some point or another. Sometimes, a major part is to blame, but a lot of times this frustrating event is caused by buildup on the battery terminals. Learning how to clean corroded car battery terminals will avoid unnecessary expenses and worry.

Method 1

Method 1 of 2:

Cleaning with Baking Soda

Download Article

1
Determine the terminal configuration of your battery. There are two types.^{[1]
X
Research source}
- If the terminals are on the side, you will need a 5/16-inch (8 mm) wrench to loosen both cable nuts.
- If the terminals are on top of the battery, you will need either a 3/8-inch (10 mm) or 1/2-inch (13 mm) wrench.
This will reduce the likelihood of accidentally grounding the cables.

Advertisement
3
Loosen the nut on the negative (-) cable clamp. Unfasten the cable from the post.^{[2]
X
Research source}
- Do the same for the positive (+) cable. If you have trouble removing either cable, attempt to twist them while pulling up at the same time.
If any are found, you need to replace the battery.
If a large rip is found, you may have to replace these parts.
6
Mix 1 tablespoon (15 ml) of baking soda with 1 cup (250 ml) of very hot water. Dip an old toothbrush into the mixture and scrub the top of the battery to remove corrosion buildup.^{[3]
X
Research source}
- You can even dip the ends of the battery cables in hot water to dissolve any corrosion on the cable ends themselves.
- The buildup is acidic and can burn your skin. To avoid it, wear gloves and safety glasses.
Remember to soak your brush in the baking soda solution as much as needed.
Make sure all the baking soda and corrosion is washed away. Dry the battery and clamps with a clean cloth.
Use petroleum jelly or a commercial battery terminal protection spray.^{[4]
X
Research source}
10
Reattach the positive (+) cable clamp to the proper terminal. Tighten the nut with your wrench.
- Repeat with the negative (-) clamp. Test if terminals are tight enough by twisting each one by hand.

Method 2

Method 2 of 2:

Emergency Cleaning

Download Article

Do not entirely remove the cables.
Repeat going in the opposite direction.
Tighten the terminals and try to restart the car.

Expert Q&A

Search

Add New Question

Ask a Question

200 characters left

Include your email address to get a message when this question is answered.

Submit

Video

Tips

You can purchase a battery cleaner spray. Some include an acid detector in the formula. These tend to be less time-consuming, but you must read the directions on the bottle, because each one is different.

Thanks
Helpful 100 Not Helpful 58
You can use a battery terminal brush or sandpaper if the buildup is too heavy for a toothbrush.

Thanks
Helpful 77 Not Helpful 66

Submit a Tip

All tip submissions are carefully reviewed before being published

Name

Please provide your name and last initial

Submit

Thanks for submitting a tip for review!

Warnings

The negative cable should always be removed first and attached last to prevent arcing.

Thanks
Helpful 83 Not Helpful 47
Always wear protective gear.

Thanks
Helpful 50 Not Helpful 34
Remove all jewelry before starting work. Rings and bracelets can become grounded or get caught on engine parts.

Thanks
Helpful 51 Not Helpful 36