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Clean battery terminals

corroded battery terminals

How to clean battery terminals

Step by step on how to clean battery terminals and posts

Before we start with the car battery corrosion cleaning procedure let’s get the terminology out of the way. The battery post is part of the battery the cable and terminal connect to while the terminal is part of the battery cable itself.

clean car battery terminals

Why did I bring this up? Because you’ll find LOTS of articles and videos out there that pretend to show you how to clean battery posts and terminals with Coke, vinegar, spray battery cleaner and baking soda.

Those products will wash away the visible car battery corrosion, the powdery white and blue corrosion substance on the outside of the battery terminals. But those products will NOT remove the corrosion between the terminal and the battery post. You’ll think you’ve done a great job because the terminal looks good on the outside, and you will succeed in removing the VISIBLE corrosion. But you’ll still have corrosion in the electrical connection and THAT corrosion, and the high electrical resistance it causes is what kills car batteries and alternators in the first place. In fact, that corrosion can reduce starting power and cause added stress to your charging system.

Proper battery terminal and post-cleaning requires disconnecting the terminals from the posts. However, many late-model vehicles require constant power to retain memory settings for the electronic throttle body, radio, memory seats, power mirrors, steering wheel angle sensor, and anti-pinch power windows. If your vehicle has any of those features, you MUST provide backup power to the PCM/ECM while cleaning the battery terminals and posts. If you don’t, you’ll have to perform re-learn procedures for every component. On some vehicles, loss of the electronic throttle body zero calibration can result in a NO-START condition, rough idle or a lack of power (can’t accelerate past 20-MPH). If you don’t have the equipment to provide backup power, at least find the re-learn procedures so you can perform them after reconnecting the battery. See this post for information on how to provide backup power when cleaning battery terminals or changing the battery.

Tools required for proper car battery corrosion cleaning

Nitrile gloves to protect your hands
Socket set
Battery terminal and post-cleaning brush
Acid neutralizer or aerosol battery terminal cleaner/neutralizer
Household spray cleaner and paper towels
Aerosol battery protector spray.

Step 1 Remove the NEGATIVE battery terminal

Using the correct size socket (usually a 10mm), loosen the hex nut on the negative battery terminal. Then wiggle the terminal and lift it off the post and out of the way. If you can’t remove the terminal, use a battery terminal puller.

remove car battery terminal

Step 2 Remove the POSITIVE battery terminal

Following the same procedure as above, remove the positive battery terminal from the post and set it aside.

Step 3 Clean off all powdery residue on the top of the battery

Wipe off the powdery corrosion residue with a paper towel. Discard the towel

Step 4 Apply acid neutralizer to the battery top, posts, and terminals

Mix baking soda with water and brush onto the battery cover, posts, and terminals. Wipe off with paper towels to dry.

Step 5 Use the battery post brush to remove post corrosion

Slide the battery terminal brush onto

battery brush

Clean battery posts and terminals with a special wire brush

the battery terminal and rotate the brush several rotations. Remove the brush and check the post surface for remaining corrosion. Repeat if necessary until the post looks shiny.

Step 6 Use the battery terminal brush to clean the terminals

Slide the tapered wire brush into the terminal and rotate until the inside of the terminal is shiny. Repeat on each terminal. Then wire brush the outside of the terminal to remove any remaining corrosion.

battery terminal cleaning procedure

Step 7 Clean the top of the battery

Grease accumulation on the top of the battery case can drain a small amount of current from the battery. So clean it off using a degreasing household cleaner. Spray it onto a paper towel and wipe off the dirt.

Step 8 Re-attach the POSITIVE battery terminal

Slide the positive battery terminal onto the positive post and tighten the hex nut with a socket until you can no longer rotate the terminal.

Step 9 Re-attach the NEGATIVE battery terminal

Follow the step above to re-install the negative battery terminal

Step 10 Spray both terminals with a battery protector spray


If the corrosion returns quickly after cleaning, see this post for the cause

For information on how to replace a battery terminal, see this post.

©, 2018 Rick Muscoplat

Posted on by Rick Muscoplat


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