How to Clean Car Battery Corrosion? – Causes and Preventions

Battery corrosion is a common issue car owners face, which is why they are constantly battling with battery issues. This could slow down the electric current supplied to the vehicle.

Corrosion is simply the deterioration of metal parts like the terminals and cable. This is usually caused by the chemical component in the battery escaping and getting in contact with these metal sections.

Once the battery fluid gets to metal parts, a chemical reaction occurs that slowly damages the surface of these components. You can then see green, white, or a blue powdery substance on the affected sections, showing that corrosion is occurring.

Today, we will be looking at what battery corrosion is, how to clean it, and its causes. Also, we will examine other related questions.

How to Clean Car Battery Corrosion

What does corrosion on car batteries mean?

Battery corrosion refers to the gradual deterioration of metal parts of the battery, majorly the terminals or cables. This usually happens when chemical components like sulphuric acid get to the metal components.

Within the battery, there is a chemical mixture called electrolyte. It is a combination of distilled water and sulfuric acid. During the charging or discharging process, ions move between the positive and negative plates, which is how they can retain charges.  

For one reason or the other, these fluids escape from the battery and get to metal parts or terminals. When this happens, a chemical reaction occurs, which is called oxidation.

Oxidation is the process where, in this case, the metal will lose electrons, which are then immediately replaced by oxygen.

As the oxidation process happens, the surface of the terminals or metal parts of the battery gets damaged gradually.

How can you tell if your battery is corroded? Look for white, blue, or greenish powdery substances on the terminal or around the cables of the battery.

What Causes Battery Corrosion?

Below are the factors that could cause corrosion on a car battery.

Leaking battery

Once there is a leak in the battery, it allows the chemical fluids and vapor within it to escape. Once they get out, it locates metal parts like the terminals and the wire connection and begins to attack or cause deterioration.

Leaks in the battery can be caused by numerous reasons, some of which include exposure to high temperatures, weak plastic body (due to age), normal wear and tear, physical damage, and more.

Also, undercharging or overcharging could cause leaks. When the battery is overcharged, the electrolyte will expand and the plastic body will not be able to contain the liquid, causing it to leak. On the other hand, an undercharging increases gasses fluid discharge, which could cause a leak.

Old battery

Old batteries will definitely have corroded terminals. Why is that? An older battery is more prone to having leaks and damaged bushing. This is because the battery’s body has been exposed to all sorts of conditions, causing it to deteriorate after some time.

Damaged terminal bushing

When you check the cells of a battery, you will notice that they are all filled with fluids. However, when you notice one terminal is corroded, check the fluids again. If the cell at the corroded part of the terminal is empty, then you have a damaged bush issue.

The bushing is a seal between the battery case and the terminal. What this does is that it prevents the fluid in the battery from escaping to the terminals.

When the battery bushing is damaged, the fluid from the battery will escape to the terminal and cause it to get corroded.

Adding too much-distilled water to the battery

Most batteries contain a mixture of Sulfuric acid and distilled water, so when the liquid level is low, people add distilled water. The problem with doing this is that it is carried out wrongly.

People tend to add too much fluid to the battery, which causes what is called overwatering. When there is too much water in the battery, it is much easier to get to the terminal, which will cause corrosion.

To avoid “overwatering” if you are adding fluid, do it after the battery has been charged.

How to Clean Car Battery Corrosion?

To clean the battery of corrosion, you will need baking soda, water, and a rag. The baking soda will be mixed with the water to make a mixture that will effectively clean the corrosion off the battery terminal. Ensure you do not pour the mixture on the battery directly, as this can damage it if it gets into it and mixes with the battery fluids.

Below is how to clean a car battery’s corrosion.

  • Switch off the vehicle and disconnect the battery terminals; remove the battery from the car if you can.
  • Put the baking soda in a container and add a small amount of water to activate the soda.

Using the rag, apply the baking soda mixture to the affected part of the battery to neutralize the battery acid reacting to the metal.

  • Use the rag to wipe the corrosion away.
  • Clean the corrosion off the terminal using a steel wire brush.
  • Clean the terminal with a paper towel or dry rag.
  • Go ahead to connect the cables.

If you do not have baking soda, use cleaning spray or vinegar. Follow the steps provided above with the cleaning alternative.

Soak the corroded terminal or cable in a cup of Pepsi for 10 minutes if the corrosion persists. It should completely neutralize the battery fluids and would make it easier for you to clean the affected metal parts.

clean car battery terminals

How to prevent car battery terminals from Corrosion?

Below are ways that you can prevent the battery from corrosion.

1. Apply terminal grease

What grease prevents the sulfuric acid, hydrogen, and other forms of corrosive substances from getting to the metal terminal?

Applying the grease to the metal terminal creates a coating that shields these contaminants from the terminal. Whether or not the sulfur or hydrogen gas from the battery gets in contact with the metal, as long as it is well-greased, it will not be corroded.

2. Monitor battery charging behavior

There are some signs that your battery will show that it is either overcharged or undercharged. For instance, if you have an overcharged battery, there will be excessive voltage readings, acid smell, bulging shape, and more.

3. Regularly check the battery terminal

Checking the battery regularly will help you notice issues with the battery, like leaks and other forms of damage. The good thing is that leaks noticed fast can be fixed before they can cause much bigger damage or even corrode the terminals.

4. Use battery protectors

There are different types of battery protectors; there is the spray protector, which, when sprayed on the terminal, creates a film that will shield it from all corrosive substances.

Also, there is the terminal cover, which we recommend all vehicles use. The terminal cover is a rubber that protects the terminal from corrosion, short-circuiting, and more.


Can corrosion kill a car battery?

Yes, corrosion can kill a car battery; how? It can do that by preventing it from charging. Normally, the alternator is meant to provide electric current while the vehicle is being driven.

However, as long as the terminals are corroded, that will not happen. The corrosion will reduce the terminal’s ability to conduct electricity. After a while of not being charged, the battery will eventually die.

Can I clean a battery terminal while connected?

We advise that you remove the battery terminals before going ahead to clean them. Doing this will prevent a short circuit, electrocution, and other damage to the battery or yourself. When removing the terminals, remove the negative first and then the positive.

What household item will clean battery corrosion?

A good household item that could be used to clean corrosion is baking soda, warm water, and a rag. If you cannot access baking soda, you can go for white vinegar or lemon juice. These two both serve as a good neutralizer for the chemical reaction.

Is boiled water OK for a car battery?

We recommend using warm water mixed with baking soda, not hot water when cleaning the battery terminal. Boiled water could be considered as it could dissolve that corrosion quite easily; however, it comes with a downside. Due to the extreme heat it could destroy rubber parts of the battery.

What happens when you put salt water on a car battery?

Avoid putting salt water on the battery at all costs. Putting salt water on the battery will significantly damage the Li-ion battery and completely damage the battery. It does not stop there, as it can also cause a chemical reaction leading to extreme fire risk.

Does a corroded battery need to be replaced?

Corrosion is a sign of a damaged battery, but does not necessarily mean it needs to be replaced. Different reasons could cause it, and these factors will determine if the battery will be replaced. If the corrosion is caused by leaks or too much-distilled water, it should be cleaned, and the appropriate fix should be done. Older batteries, however, should be changed.

What is best to clean car battery corrosion?

The best way to clean battery corrosion is by using a battery cleaner. It is a product specifically made to clean corrosion off the battery. If you cannot access the product, you can then opt for baking soda and water. You will have to be careful using this mixture as it could cause damage if it comes into contact with the electrolytes. 

Final Words

Once you notice that your vehicle’s battery is corroded, the first step is to determine the cause. This will help you find a better fix for the problem. Going directly to clean the corrosion without solving the underlying problem will mean that the issue will come up again. Ensure to replace the battery if it has been used for more than four years, as this could cause constant corrosion. 

Akindayini Temiloluwa

I am passionate about everything automotive. Right from when I got my first toy car as a kid, I developed an interest in the inner workings of vehicles. As I grew up, my love for mechanical stuff became more substantial enough for me to pursue a career in it. My goal as an automotive content writer is to simplify the most challenging concepts for my readers, help them self-diagnose what may be wrong with their vehicles and offer real value for their time.

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