What Causes Car Battery Corrosion and How to Remove It


The most highly likely car trouble that you will be encountering is battery corrosion. If for some reason, I have a busy schedule and forget to have my car check, at the very least, I always check under the hood and see if there are any powdery white or bluish substances forming at the terminals of the car battery. 

If that is the case, I would immediately send the car for a further checkup to find out if there is something wrong with the battery.

Some might say that I am overreacting to the thought that a little corrosion might cause harm to the entire car, but corroded battery terminals can lead to severe problems in your engine if it is left unchecked. It could be the reason why your car suddenly stops functioning or have an engine breakdown in the middle of nowhere.

What Does Corrosion On Car Battery Mean?

There are a lot of issues surrounding battery corrosion, and some say that it is normal to have that around the battery terminals. Corrosion on your car battery is indeed part of the normal wear and tear of your car. However, it can worsen, especially during hotter seasons, when the temperature is high.

Based on my experience, having a corroded car battery means that I would not be able to start my car. Even with exerting a lot of effort, the car just simply fails to jump start. Having these issues with the car battery also means that my car would not have enough power to sustain other parts of the car, such as the radio or lights.

The computer within the car is powered by the battery and if it does not receive any power that it fails to operate. This can lead to issues with the sensors and alerts that will keep us safe while on the road. If you continue to ignore these issues and fail to have your car checked up, this could put a risk on all of our safety, including your family.

What Causes Corrosion on Car Batteries?

Car batteries are placed inside the car and are generally protected from the natural external elements. However, I would also ask myself, how does a well-protected item inside the car get affected by corrosion? This led me to research what car batteries are made of and how they get affected by different things, which causes them to corrode. As I've noticed, it all boils down to chemistry.

The most common reason behind this build-up is the fact that many batteries contain sulfuric acid. The rise in temperature, especially during the summer seasons, causes gases to be released from the battery through the vents. These gases are created due to the rise and fall of the temperatures. These gases then get mixed with other elements outside of the battery, thus causing the powdery white to bluish build-up that you normally see on the surface.

However, after spending time researching on what can cause car battery corrosion, I've discovered there are a lot of reasons why car batteries get corroded.

1. Battery Age

Age plays a huge role in the overall integrity of the car battery. One thing I noticed is that the car battery that is still being used beyond 5 years tend to develop more terminal corrosion than those that are still new. No matter how frequently I maintain the vehicle, it will always start to develop some corrosion over time. Batteries usually have a lifespan of about 5 years, and if you continue to use them over time, it will always succumb to the normal wear and tear, thus influencing the corrosion and the overall performance of your car.

2. Overcharging

Another huge factor that can lead to battery corrosion is overcharging. This usually happens when I try to charge the batteries way too often and way too much. Overcharging, as I have found out, can increase the temperature in the batteries, which expands the electrolytes found inside. This causes pressure within the batteries, and it leaks out, causing the electrolytes to flow through the cracks. The electrolytes then get tangled up in the terminals, thereby causing the corrosion.

3. Too Much Water

One of the factors that I noticed that added to the corrosion of the car battery is adding too much water. I highly advised avoiding putting too much water in the refillable battery, especially if it has already gone beyond the mark. Make sure that you also fill the battery up on a cool day so that the liquid can have enough space to expand, especially when the temperature rises again. Adding too much water seemed to overflow the battery, and the excess liquid flowed out through the vents, thus causing deterioration.

4. Copper Clamps

As I mentioned a while ago, chemistry plays a huge role in the corrosion of batteries and the formation of the buildup around the terminals. Copper clamps are generally used as a conductor as they don't easily corrode. However, when electricity is produced through the clamps, it mixes with the sulfuric gases that come from within the battery, thus forming what is called copper sulfate. Copper sulfate is the bluish powdery substance you see building up on the terminals. This is the reason why I mostly have trouble starting my car since electricity doesn't conduct well with the presence of copper sulfate.

5. Electrolyte Leakage

I'm currently using a sealed battery, which prevents any leakage from happening, but other battery types need regular topping and maintenance, and this can cause leakage and spillage. The exposure of electrolytes in different key areas of the battery can cause corrosion and certain buildup of substances that may cause the deterioration of the car battery.

How To Remove Car Battery Corrosion

Knowing that I have car battery corrosion is just half the case. Learning to remove the corrosion is the key element to saving the battery and the car overall. The first thing that I do in removing the corrosion from the car battery is to disconnect the battery cables first. This is an important rule that you and I have to follow to avoid getting burned or shocked. Always disconnect the negative cable first before the positive one. I always keep reminding myself to do this for my safety.

After removing the battery, I would then check the cables if there any damage and see if they are worn out. I would also check if they are dried or cracked or even splintered in some way that could also cause corrosion. If I do find some form of damage, I have them replaced immediately.

Now, after checking the cables, it is time to remove the corrosion from the battery and the terminals. I would simply use a cleaning agent or the ones that I found in car maintenance shops or sections in the store. This will help clear out the corrosion from the battery and help reduce the acidity of the battery as well.

Apart from using commercial battery cleaning agents, I would also like to share a few tricks if these cleaning agents are not available in your area. I've discovered that these tricks are helpful in cleaning and removing the substances that cause corrosion without having to invest a lot of money into it.

1. Baking Soda

I would mix baking soda and water first and apply them to the terminals to remove copper sulfate build-up. I also make sure that the battery terminals are removed, and the car's ignition has been turned off for safety purposes. I just pour the baking soda solution over the brush the terminals until the build-up is removed. I then use clean water to clean up the rest of the terminal and smear some grease to protect the terminals.

2. Coke or Soda

Another trick that I've used is to incorporate soda into the mixture. Simply pour soda on the terminal and either brush or wipe the residue. Coke has carbonic acid, which is a great way to remove the residue from the terminals.


Car batteries are vital to the overall function of a car. Without it, we would all be left stranded without having to use our cars. This is why I prioritize the integrity of the car battery by maintaining it frequently. However, if I find myself busy or unable to do checkups, I also make sure that I take preventive measures to delay any corrosion from happening to the battery. Measures such as anti-corrosive sprays and proper battery charging are just a few things that I usually do to help prevent corrosion from happening.

About the Author Simon Adams

Simon graduated with a Mechanical and Electrical Engineering Degree. He has over 20 years of servicing experience in both Japanese and German car dealerships. He now acts as a freelance mechanic's instructor for local schools.

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