How to Clean Corroded Car Battery Terminals

Cleaning with Baking Soda

Determine the terminal configuration of your battery. There are two types. 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.

Make sure your car is turned off. This will reduce the likelihood of accidentally grounding the cables.

Loosen the nut on the negative (-) cable clamp. Unfasten the cable from the post. 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.

Examine the battery for cracks that may be leaking acid. If any are found, you need to replace the battery.

Check the battery cables and clamps for tears. If a large rip is found, you may have to replace these parts.

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. 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.

Use the toothbrush to scour the battery clamps and posts. Remember to soak your brush in the baking soda solution as much as needed.

Rinse the battery and cables with cool clean water. Make sure all the baking soda and corrosion is washed away. Dry the battery and clamps with a clean cloth.

Lubricate all exposed metal on battery terminals, posts and clamps. Use petroleum jelly or a commercial battery terminal protection spray.

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.

Emergency Cleaning

Keep a pair of gloves and correct-size wrench in your trunk or back seat.

Loosen each terminal slightly with your wrench. Do not entirely remove the cables.

Pour cola over the battery from the center outward in one direction. Repeat going in the opposite direction.

Allow it to soak for two minutes, then rinse off with water. Tighten the terminals and try to restart the car.