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How to Clean Car Battery Corrosion: 3 Simple Steps to Follow

Corrosion can form in and on the battery’s terminals and around the battery cable ends, especially when the engine and battery are not running, causing the terminals to oxidize. This issue is often overlooked, however car battery corrosion can cause trouble starting your car, and the battery may not be fully charging when you are driving. Learn the simple steps of how to clean car battery corrosion now to extend your battery’s lifespan and optimize its performance. 

In this comprehensive guide on how to remove corrosion on car battery, you will learn the different causes for corrosion, the detailed steps and pro tips on cleaning car battery corrosion, plus many handy maintenance tips to keep your battery always in tip top shape. 

What is Car Battery Corrosion?

How To Clean Car Battery Corrosion
Car battery corrosion is a normal wear and tear process.

Corrosion is a problem with all types of car battery. Car battery corrosion looks like a crusty, ashy substance that forms around the battery ports. This type of corrosion is created because of the chemical reaction that goes in the terminals and battery cable ends. 

Most batteries are filled with sulfuric acid, and when the battery is charging or discharging. During the charging and discharging process, this acid is heated or cooled producing a by-product — hydrogen gas. Corrosion is caused by the hydrogen gas being released from the sulfuric acid inside the battery. 

As the gasses react to the external environment, it produces a corrosive environment. Since the terminals are in direct contact with the battery, they are exposed to this corrosive environment or “acidic fumes”, thus are prone to corrosion.

Another type of corrosive process you might see on your battery terminals occurs when the copper on the terminal clamp gets wet and reacts with the lead electrode it is connected to. This type of corrosion results in a greenish substance on the terminal itself. Otherwise, if the terminal clamps are made of aluminum, the corrosion will be in the form of a white substance.

Finally, another corrosive process called “sulfation” happens when a battery isn’t regularly recharged, either because it’s only being driven for short trips or because it’s aging. This type of corrosion will typically form white sulfur crystals on the negative battery terminal or occasionally around the battery itself if it’s leaking sulfuric acid. In some cases, these sulfur crystals can also build up around the positive electrode if the alternator is overcharging the battery.

How Corrosion Affects Your Car

In essence, the battery can only do its job when the connections are intact. Corroded cables and terminals, or loose fitting terminals alike, can limit the alternator’s ability to charge the battery and provide power to the car and its electrical accessories like radio and headlights.

car battery corrosion
Battery terminals corrosion impairs the connection to your battery.

It should be noted that small amounts of corrosion are not usually a serious problem; it simply reflects your car’s normal wear and tear over the years. That said, corrosion can get worse and starts to become an issue especially when subjected to higher temperatures during the summer months. In warmer conditions, larger buildups are more likely to form, which will act as an insulator that will prevent the battery from accepting or delivering a charge.  

Leaving corrosion unchecked will cause problems over time, as corrosion impairs the connection to your battery and in many cases can lead to permanent battery failure. When that happens, you will have to go through the troubles of removing and replacing your battery.

Battery is a critical component that gets your car going. Its health affects whether your vehicle can run smoothly or at all, and “health” here also includes basic hygiene maintenance that every driver must perform on a regular basis. 

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What Causes Battery Corrosion? 

To properly care for your precious batteries, before we proceed to cleaning car battery corrosion, you should grasp the most common causes of car battery corrosion below:

Undercharging

If corrosion occurs on the negative battery terminal only, this is typically a symptom of your car’s battery being undercharged. The most common reason for such undercharging is the alternator not having sufficient time to replenish lost battery capacity due to high electrical demand, and/or the vehicle is powered only for a short period of time each time it runs. 

Overcharging

If battery corrosion is present on the positive battery terminal, this is a symptom of overcharging. If your battery is either the flooded or sealed type, overcharging the battery can push the electrolyte out of the vents or cracks, thus causing corrosion.

Reaction in Copper Clamps

Copper is used to make the clamps that connect the wires and the battery. If you are good at chemistry, you will definitely know that copper is unable to corrode all by itself. However, the current which overpasses through it produces copper sulfate, thus resulting in corrosion on the battery terminal.

Overfull Battery

Filling too much battery water into a battery is another reason for corrosion on battery terminals. And you know battery terminals are made of metals which can be corroded. Therefore, if you fill too much battery water into your battery, the excess water will come out of the vents then corrode your battery terminals.

Electrolyte Leakage

One of reason causing battery terminal corrosion is electrolyte leakage. If a battery is not well-maintained, the electrolyte will leak out and accumulate on the battery terminals, causing corrosion.

Battery Age

If your battery is over 5 years olds, of course, you will see corrosion on it. So in this case, don’t hesitate to replace the expired battery with a new one.

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How to Clean Car Battery Corrosion: 3 Detailed Steps

You can learn how to clean corrosion off car battery by using both household items and professional-grade supplies. Here, we will show you how to handle with battery corrosion by both methods in 3 steps.

Step 1: Removing & Inspecting the battery terminals

How to clean corrosion off car battery
How to clean corrosion off car battery (Source: Yourmechanic.com)

First of all, negative and positive cable ends need to be disconnected from the battery in order to clean the battery terminal connections properly.

Equipments needed:

  • Goggles for protection
  • Rubber gloves
  • Battery terminal wrench

Caution: Car battery contains acid inside which may cause accidental injuries. Therefore, when working with an vehicle battery, you have to wear eye glasses and gloves in order to protect yourself from acid.

To do this step, follow the direction below:

  1. Loosening the battery cable ends. Disconnecting the negative cable is the first thing you have to do, then disconnecting the positive cable.

Now, it’s time to use the battery cable wrench. Place it on the battery cable end nut then twist it counter-clockwise.

  1. Loosening the nuts. If your battery is a top-post battery, loosening the nuts till there is no tension on the clamp is what you will just need to do.
  2. Loosening the cable end. If your battery is a side-post battery, you will need to loosen the cable end till it is removed.
  3. Lifting the top-post battery cable ends off the terminal. To do this, you should pry and wiggle the cable end off.

After removal, perform a visual inspection of the battery cables for excess wear or corrosion. Frayed or damaged battery cables are a common reason for difficult starting or failure to start. 

Look for dried, cracked, and peeling insulation, which is the plastic or rubber cover on the cable, and replace them if needed. Also check if the copper strands are intact; they serve to limit current flow and easily become brittle when exposed to the elements. Replace the battery cables in case of damage.

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Step 2: Cleaning the battery

2.1 Clean the battery by using household items

Pro tips: Here is how to clean car battery corrosion using available household items:

Equipments needed:

  • Baking soda
  • Water
  • A wire brush or a stiff-bristled brush
  • Petroleum jelly
Clean corrosion off car battery
Clean corrosion off car battery (Source: Yourmechanic.com)

As you can see, with this method, you don’t need to use specific materials to clean the battery terminals of your car. Some simple household things are enough for you to restore a proper connection and clean the battery of your car.

* Important note: Never use coca-cola to remove battery corrosion. The synthetic sugars and phosphoric acid in coca-cola can cause further damage to your engine and surrounding components. 

  1. Firstly, you cover both battery terminals by baking soda. Sprinkle enough baking soda powder to make a coat for terminals and the small area around the terminal as well.
  2. Secondly, you need 2 tablespoons of water to pour on each terminal. After pouring water, you will see the baking soda reacting and bubbles will appear ferociously from the chemical reaction.

The chemical reaction between the mixture of acidic corrosion + baking soda + water on the terminals of car batteries will neutralize the acid, thus it is safe for you to handle.

  1. Do the same procedure on cable ends. You repeat the same procedure on the battery cable ends.
  2. Scrubbing the terminals is the next thing you need to do immediately. After you do the neutralizing procedure, the next step is using a stiff brush to scrub off the car battery corrosion. You can use an old toothbrush or a wire brush to scrub all around the cable end inside and out as well as the terminal of your car battery.
  3. Rinsing with water. After you remove all the corrosion, the next step is rinsing the cable ends and the battery carefully with clean water.
  4. Drying the battery completely. After rinsing with water, you need to let your car battery dry entirely. Using compressed air is an effective way to blow the battery dry.
  5. Place a thin layer of petroleum jelly on your battery terminal. You need to smear a thin layer of petroleum jelly on the cable end and the car battery terminal as well. The layer of petroleum will conduct electricity between the cable end and the battery terminal and also prevent corrosion appearing on the battery terminals.

Check out the video to know how to clean car battery corrosion in cheapest way: 

2.2 Clean the battery by using professional-grade supplies

Equipments needed

  • Battery terminal brush
  • Battery cleaner spray
  • Water
  • Grease or protective spray
Clean corrosion off car battery using a kit of specific materials
Clean corrosion off car battery using a kit of specific materials (Source: Yourmechanic.com)

With the kit of specific materials, you can easily clean your car battery in a professional way. Here below is how to do:

  1. Spraying the cable ends. After disconnecting all battery cables, spray a commercial-grade battery cleaning agent if you find corrosion on the battery or battery cables. Using a commercial-grade battery cleaner is important because it not only removes the battery corrosion but also neutralizes the battery acid, and it is so much more effective than home remedies. A lot of spays are produced with a dye inside them that helps show up acid appearance. For instance, a yellow spray may change into purple if there is a presence of acid.
  2. Soaking for some minutes. Soak the battery and the cable ends in the spray for some minutes. You may notice the color of the spray dissipate.
  3. Spraying the cable ends and the battery terminals again. Using the cleaner spray to lightly spray the cable ends and the battery terminals again. If you observe that the color doesn’t change or there is a slight change, this means the acid is neutralized. Reapply if necessary. 
  4. Rinsing with water. Spend water to rinse the battery entirely. Carefully clean spray off the car battery and the areas around it.

Caution: You should be careful when using battery cleaner spray as some dyes in cleaner spray will stain your paint another color.

  1. Using a battery brush. After rinsing with water, it’s time to use a battery brush to clean the cable ends and the battery posts to remove additional residue.
Using battery brush to clean corrosion off car battery
Using battery brush to clean corrosion off car battery (Source: Yourmechanic.com)
  • You should put the battery brush over the battery terminal and twist it from 3 to 5 times around the post if you have a top-post battery. Any corrosion on the battery terminal will be whisked away by the stiff wire bristles. Additionally, you can use a stiff-bristled brush to do it for a side-post battery.
  • Uncapping the battery brush and then inserting it into the cable ends. In this step, you should turn it at least 3 or 4 times around in order to remove all corrosion which is built up inside the clamp.
Turn battery 3-4 times to clean corrosion inside the clamp
Turn battery 3-4 times to clean corrosion inside the clamp (Source: Yourmechanic.com)
  1. Spraying the car battery terminals. Implementing preventive measures is just as important as learning how to clean car battery corrosion. Proper battery corrosion prevention is critical to the health of the car battery and your vehicle’s performance. After all that cleaning, remember to spray a battery corrosion preventative spray or brush-on compound, or apply a generous layer of petroleum jelly, or Vaseline, on the battery posts on the battery and battery terminals of the battery cable.
Using petroleum jelly to protect car battery from corrosion attacks
Using petroleum jelly to protect car battery from corrosion attacks (Souce: Yourmechanic.com)

Step 3: Reconnecting the car battery terminals

In this step, a battery terminal wrench is all you need in order to make the cable ends reconnected.

Replacing the cables. First, you install the positive cable back into its position. For some top-post batteries, you will have to fully wiggle or tap the cable end down into its position.

Tightening the nut. You need to tighten the nut on the clamp to make it snug. Then try to add another quarter twist.

Placing negative cable. You reconnect the negative battery cable in the same way like what you do with a positive cable.

Find out How to clean car battery corrosion by Coke in the video below

30 Comments
  1. Muhangi M says

    That was useful infomation,iliked it very much,thank you CAR FROM JAPAN!

  2. Gadson says

    Food for thought for my machine

  3. Prince Nyendwa says

    Hi, thanks for all the tips you post they really help. My car battery drains on its on even if you remove the terminals after parking it still drains. Any idea on how to over come this issue?

    1. Trang Tran says

      Thank you for contacting Car From Japan. However, we cannot answer your problem because there is many things we need to see at your car. I suggest you to bring the car to a local mechanical shop o solve your problem.

  4. Abongo Stephen says

    Liked the information on cleaning of corrosion on battery. Wonderful

  5. Crescent Bwengye says

    must have information for every owner and prospective car owner

    1. Trang Tran says

      We are happy to receive your comments. Please share with your friends so they can enjoy this article, too.

  6. Paul kirwa says

    Your informative tips are really of great help to motorists.

    1. Trang Tran says

      We are glad that you like the article. Don’t forget to share with your friends!

  7. kenn says

    Can I change engine oil by myself, and to do it?

    1. Trang Tran says

      U should bring your car to a mechanic if u are not confident about DIY

  8. BUSINDO HASSAN says

    Thanx da knowledge

    1. Trang Tran says

      Thank you. We will provide more useful information like this. Stay tuned

  9. karu joseph says

    That very good information

    1. Trang Tran says

      Thank you. We will provide more useful information like this. Stay tuned

  10. Kennedy says

    Perfect… learned a new thing on corrosion management

    1. Trang Tran says

      We are happy to receive your comments. Please share with your friends so they can enjoy this article, too.

  11. Ocen Samuel says

    To avoid that you have clean and after aply grease can also be ok

    1. Trang Tran says

      Thank u for your comment

  12. Hara Benjamin says

    Thank you for the information . is it a good way to clean battery corrosion with hot water?

  13. Moddie says

    THANKS FOR THE USEFUL INFOR

  14. Blessure says

    And Coca-Cola does the work too

  15. Indika Marasinghe says

    thank you very much. verry good information.thank you again.

  16. indika Marasinghe says

    thank you

  17. Rebecca E. Cox says

    Hello Tsukasa Azuma, Thank you for sharing the useful information. This post I found very much knowledge and will help me so much when I clean My car battery corrosion. Keep up the useful article.

  18. Francis says

    Hi Azuma, we have been using Hot water in the past and its worked well is that dad for the battery.

  19. Jasmine Paulos says

    Using baking soda is such amazing method to remove corrosion.Corrosion is a very harmful and dangerous disaster and If not taken care it might make it useless.Thanks for sharing this article.

  20. Papita says

    You can also use Coca-Cola drink. Very effective

  21. David chobela says

    What is the right engine oil for Toyota corolla Spacio 1nz 2001 to use in southern african region?

  22. Alexander MB says

    DO NOT Remove any of your battery clamps before making a bridge to another spare battery! To prevent from a dead ECU or lock car radio, please follow this step. Take spare small 12 volt battery and make the connection to the back of the clamps, then slowly remove the old baterry on the car, then clean it as instructed above. The spare small batterry should keep the memory to the ECU and radio. Hope this help.😊

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