Corroded Car Battery - How to Clean and Prevent It

Car battery corrosion is often an underestimated issue, but it decreases the car's battery performance and operating life. Also, a corroded car battery can damage the rest of the electrical wiring, car body, air conditioning, and other systems that are nearby.

Car battery terminal corrosion happens when the car battery vapors, consisting mostly of sulphuric acid and hydrogen, come in contact with the battery terminals (mostly led) and battery cabling (copper) under the car's hood, heated by the engine...

Updated: October 17, 2024.

How to Clean Car Battery Corrosion

Sulphuric acid vapors, hydrogen, copper, lead, and probably a few more compounds lead to the build-up of battery corrosion, mostly consisting of bluish copper and lead sulfates, and similar salts.

Such buildup looks nasty and can damage the battery, wiring, and other parts of the car, as well it can cause chemical burns on the skin, it can damage the clothes, and similar.

Note: When dealing with chemicals like these, always wear protective goggles and protective gloves, although other protective measures are welcome, too.

A corroded car battery can be cleaned in a few simple steps:

• Disconnect the Battery
• Check the Battery Cables and Terminals
• Remove the Corrosion
• Reconnect the Battery

Disconnect the Battery From the Car

Before disconnecting the car's battery, check if your car allows that - some modern cars feature electronic systems that are constantly powered by the car's battery and if the battery is disconnected for whatever reason, the engine and other subsystems may become blocked (safety system) and the car must be towed to the nearest certified car shop to unblock the electronics.

If you have such a car or just want to play safe, before disconnecting the battery, connect the 12V car battery tender/maintainer to the car (there is not 100% guarantee that that will work).

Now, first disconnect the negative battery cable (sign "-", black cable) before disconnecting the positive battery cable (sign "+", red cable).

Also, if it is possible, it is a good idea to remove the battery completely from the car.

Check the Battery Cables and Terminals

 Now, check the battery cables and terminals for any signs of damage, including damaged insulation, it is time to replace the cables right away, or at least as soon as possible.

Also, check that the car's systems near the battery are not showing signs of corrosion damage - if present, consider taking the car as soon as possible to the nearest licensed car shop so that they can check the car more thoroughly.

Remove the Corrosion From The Battery Cables and Terminals

In order to remove the corrosion from the battery cables and terminals one may use commercial products (liquids, spray bottles, etc.) but the ordinary baking soda will do the job just fine.

So, take a glass of warm water, add a tablespoon of baking soda and mix it thoroughly.

Now, take the old toothbrush or any similar brush and apply the baking soda solution over corroded areas and brush everything thoroughly - baking soda will neutralize and clean the battery corrosion very quickly.

Note: while some people prefer to do this job using Coca-Cola or similar beverages, note that baking soda solution contains only water and baking soda, while soda beverages contain various sugars, artificial colors, sweeteners, various acids, etc. Such mixture can even damage car components even more, so if You prefer cleaning the battery corrosion with Coca-Cola, be sure to remove the battery from the car completely. Better safe than sorry.

During the cleaning, be sure that soda solution mixed with battery corrosion doesn't come in contact with other car parts - again, if possible, take the battery out of the car completely.

Instead of toothbrushes, other types of brushes can be used, including car battery terminal brushes (Amazon link, opens in the new window) that can be found rather cheap.

Very popular Schumacher BAF-B1 Battery Terminal Cleaning Brush (Amazon link, opens in the new window)

After cleaning, be sure to rinse the battery cables, terminals, and the battery itself.

Before reconnecting the battery, be sure to dry the battery using an air compressor, dry cloths, or something similar - electricity and liquids don't come together very well.

Reconnect the Battery

Now that the battery terminals and cables are clean, it is time to reconnect the battery.

First of all, check the battery cables and terminals once again - with no battery corrosion present, one can better see any potential damage.

When reconnecting the battery, reconnect the positive battery cable (sign "+", red cable) first and then the negative battery cable (sign "-", black color).

However, before actually reconnecting the battery, in order to prevent future battery corrosion, it is a good idea to place anti-corrosion pads (Amazon link, opens in the new window) around the battery terminals.

Such battery terminal protectors are basically fiber washers that contain chemicals that neutralize battery acid, preventing future battery corrosion.

Note: anti-corrosion pads don't last forever and in order to protect the battery from corrosion, they must be replaced periodically.

To protect the battery even further, it is highly recommended to also apply battery anti-corrosion lubricant/spray (Amazon link, opens in the new window) or silicone-based grease.

And that would be all.

Of course, if You want, this task can be done in any certified car shop - they can also test the battery to accurately check its condition and if required, replace the battery and the battery cables with new ones.

Frequently Asked Questions (FAQ)

Here are some of the most common Frequently Asked Questions about cleaning the car battery corrosion.

What causes corrosion on car batteries?

Corrosion on car batteries is typically caused by a chemical reaction between the battery terminals and the hydrogen gas released by the acid within the battery. This reaction can lead to the formation of sulfate crystals or other corrosive substances on the terminals.

Other contributing factors can include exposure to moisture, overcharging of the battery, and aging, which can lead to deteriorating seals or cracks and allow gases and acid to escape more easily.

How does weather affect car battery corrosion?

Weather significantly impacts car battery corrosion. High humidity and wet conditions can accelerate corrosion by increasing the conductivity between the battery terminals, which promotes corrosive chemical reactions.

Conversely, extreme cold or heat can stress the battery, causing it to expand and contract, which may break down its internal structure and seals, leading to leaks that also contribute to corrosion.

How can I tell if my car battery has corrosion?

You can tell if your car battery has corrosion by looking for white, green, or blue powdery deposits on the battery terminals and cables. This buildup typically indicates corrosion. Additionally, you might notice that the car struggles to start, or the battery terminals may appear swollen or have a crusty texture.

These signs suggest that it's time to inspect and clean the battery to ensure it maintains a good connection and functions properly.

What safety gear should I wear when cleaning battery corrosion?

When cleaning battery corrosion, it's important to wear appropriate safety gear to protect yourself from acidic substances. Here's what you should wear:

• Safety Goggles: To protect your eyes from any splashes or particles.
• Rubber Gloves: To shield your hands from the corrosive materials and prevent any skin contact with the battery acid.
• Protective Clothing: Wear clothes that cover your arms and legs to minimize skin exposure.
• Respiratory Protection: If you're working in a poorly ventilated area, consider wearing a mask to avoid inhaling any fumes.

These precautions help prevent any injuries while handling potentially hazardous materials.

Can battery corrosion cause my car not to start?

Yes, battery corrosion can cause your car not to start. Corrosion on the battery terminals interferes with the electrical conductivity needed for starting the engine. It can create resistance or a poor connection, preventing the battery from effectively delivering the power required to start the car.

Cleaning off the corrosion can restore the connection and often resolve starting issues.

Is there a way to clean battery corrosion without removing the battery cables?

Yes, it's possible to clean battery corrosion without removing the battery cables, but it's less thorough than removing them for a full cleaning. Here’s a basic method:

• Turn off the Car: Ensure the car is off and the keys are removed from the ignition.
• Apply Baking Soda: Sprinkle baking soda directly on the corroded areas. Baking soda neutralizes battery acid and helps to loosen corrosion.
• Add Water: Carefully pour a small amount of water on the baking soda to create a reaction that will dissolve the corrosion.
• Scrub Gently: Use a toothbrush or small brush to scrub the terminals and clamps, removing as much corrosion as possible.
• Wipe Down: Use a damp cloth to wipe away the residue and dry the area thoroughly.

While this method can reduce surface corrosion, for best results and to prolong the life of your battery, it's recommended to disconnect the cables for a comprehensive cleaning if the corrosion is severe.

Can I clean car battery corrosion myself, or should I seek professional help?

You can certainly clean car battery corrosion yourself, and it's a manageable task for most car owners. With basic tools like a wire brush, baking soda, water, and protective gear, you can effectively remove the corrosion.

However, if the corrosion is extensive, or if the battery has other issues like leaks or damage, or if the battery should NOT be disconnected from the car, it’s advisable to seek professional help. Mechanics can provide a thorough inspection and ensure that there are no underlying issues that might complicate a simple cleaning.