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How to Safely Clean Car Battery Corrosion

Medically Reviewed by Dany Paul Baby, MD on April 07, 2022

Your car battery provides the electricity you need to start your car. It also powers your car's electrical components, such as the stereo and power windows. If corrosion builds up on your car's battery, it can interfere with the battery's ability to function. 

If your car is having trouble starting or you notice problems with the electrical parts of your car, you may need to clean corrosion off the battery. Even if your car can start, battery corrosion can lead to other problems, such as damage to your vehicle's: 

  • Chassis
  • Electrical wiring
  • Air conditioner lines

In this article, you'll learn everything you need to know about how to clean battery corrosion.

What Is Battery Corrosion?

Battery corrosion shows up as a white-, green-, or blue-tinged substance on your car's battery posts, terminals, or cables. Battery acid releases hydrogen gas that reacts with the air and forms a corrosive environment. This environment allows the battery to corrode.

Is Battery Corrosion Dangerous?

Yes, battery corrosion is dangerous. Battery corrosion is caustic and can irritate or burn your skin or eyes if they're exposed to it. Battery corrosion left unchecked can also lead to further damage to your car that will be more expensive to repair the longer you wait.

Car batteries contain sulfuric acid, so you should be careful when handling them. Because battery acid can produce explosive gases, the batteries are designed with vent caps to release those gases. You should only work with batteries in well-ventilated areas. You should also keep any metal tools or other metal objects away from the top of the battery to prevent a short circuit. Finally, never attempt to charge a damaged battery. 

After handling a car battery, take the following precautions: 

  • Wash your gloves off with water.
  • Wash your hands with soap and water.
  • Neutralize any spilled battery acid with baking soda.

If battery acid gets on your skin, flush the area with clean, lukewarm, gently flowing water for 30 minutes. If it's still irritated after that, continue flushing and seek medical treatment. If battery acid gets in your eyes, flush them in the same way as you would flush your skin and for the same amount of time. But in this case, you should seek immediate medical treatment.  

What Causes Battery Corrosion?

Battery corrosion has several different causes, including: 

Overcharging. If you overcharge your battery, the temperature can get too high. This may cause electrolytes in the battery to expand. Batteries have vents for pressurized battery fluid to escape so that they don't explode. If battery fluid leaks from the vents, it can cause corrosion.   

Damage to the battery. Cracks and damage to your battery can cause battery fluid to leak. Leaking battery fluid can cause electrolyte buildup on the terminals, which causes corrosion.

Overfilling your battery. Some batteries need to be refilled with water to operate correctly. If you overfill a battery, the excess water comes out through the battery's vents. If water comes in contact with the battery terminals, corrosion can form.   

Copper clamps. If your battery is leaking sulfuric acid and it comes into contact with copper clamps, a chemical reaction will take place. The resulting copper sulfate causes corrosion.  

Age. Car batteries often have a 5-year lifespan. If yours is nearing the end of its life, it's normal to start to see corrosion.  

What Supplies Do You Need to Clean Car Battery Corrosion?

If you decide to remove battery corrosion yourself, gather the following supplies when you're ready to start: 

  • Stainless steel wire brush
  • Baking soda or a battery cleaning agent
  • Water
  • Microfiber cloth
  • Pliers
  • Wrench
  • Gloves

How Do You Clean Car Battery Corrosion?

Removing battery corrosion is a fairly simple and inexpensive task. Just follow these steps: 

Disconnect the battery cables. Start by putting on gloves to protect your hands. If you have a newer car, you may have to enter a security code in your navigation system when disconnecting the battery cables.  

Disconnect the negative battery cable first. It's usually marked with a negative sign or the abbreviation NEG, or the cable may be black. Then, remove the positive or red cable. You may need to use pliers or a wrench to get the cables loose. 

Check the cables carefully for any signs of excess wear or peeling insulation. If your cables are damaged or frayed, you'll need to replace them. 

Neutralize the corrosion. Apply a paste of baking soda and water or use a battery cleaning spray to neutralize the corrosion and start removing it. If there's a lot of corrosion, you may need to use a wire brush to scrub it off the terminals. When you've finished scrubbing, rinse it away with water. 

Dry the battery. Use the microfiber cloth to dry the battery, terminals, and cables once you've removed the corrosion.  

Reconnect the battery cables. Once the battery is dry, reconnect the cables. Be careful not to overtighten them. If you replaced your cables, this is when you'll connect the new ones. 

How Can You Prevent Battery Corrosion?

Here's how to prevent battery corrosion: 

Perform routine maintenance. Check your battery every so often for signs of corrosion. It's a good idea to do this when you get your oil changed. Regularly checking your battery will allow you to spot any signs of corrosion early on and deal with it before it causes more problems. 

Use a protective treatment. You can buy commercial brush-on treatments or sprays at auto parts stores to prevent corrosion from forming. Disconnect the battery cables before you use them to get between the terminal and the cable.  

Make sure your battery is properly charged. Overcharging or undercharging your battery can lead to corrosion. If your battery is routinely over- or undercharging, take it to a mechanic so they can figure out why.  

Use petroleum jelly or battery grease. Coating the terminals with petroleum jelly or battery grease will help prevent corrosion. Remove the battery cables before you apply either one. Battery grease will last longer in a hot engine because it's silicone-based.  

Show Sources

SOURCES:

Canadian Centre for Occupational Health & Safety: "Garages - Batteries."

Consumer Reports: "Fall Cleanup and Maintenance for Your Car."

Department of Physics University of Illinois at Urbana-Champaign: "Q & A: Car Batteries."

University of Missouri Extension: "Winter car care to keep your vehicle running through the cold."

University Technical Institute: "What Is Battery Terminal Corrosion?" 

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