Skip to Content

Blue Stuff on Car Battery: What Is It & How to Remove?

One of the significant parts of a car is the battery. The car battery powers the headlights, dashboard lights, and engine. Problems with the car battery or wiring can cause issues and the whole vehicle to malfunction.

What is the blue stuff on battery terminals?

The blue stuff on battery terminals is hydrated copper sulfate. If you see white powder around the battery terminals of your car battery, that is anhydrous copper sulfate. When anhydrous copper sulfate gets moist, it becomes blue. You can see blue stuff around battery terminals made of copper.

Batteries provide electrical energy required by the car. Over time, as the battery operates, the battery terminals corrode. This corrosion produces blue and white stuff that you can see around the battery terminals.

You can identify a battery terminal corrosion as they are usually a white, green, or blue powder that sits around the battery terminals. 

The white powder around a battery terminal may be lead sulfate or anhydrous copper sulfate, depending on the material used to manufacture the battery terminals. In most cases, the white powder is anhydrous copper sulfate since battery terminals are made of copper.

The blue crusty stuff around a battery terminal is hydrated copper sulfate. When anhydrous copper sulfate gets moisture, it becomes hydrated copper sulfate which is blue. This blue power, hydrated copper sulfate, can be seen around the battery terminals made of copper.

Is blue corrosion on a car battery normal? Can corrosion ruin a car battery?

The blue corrosion of battery terminals is normal. It happens due to the wear and tear of a battery. As a battery is used for a long time, the battery terminals get corroded due to chemical reactions at the battery terminal.

One of the concerning reasons behind decreased battery life and performance is the corrosion of battery terminals. The white or blue mark is an insulator and prevents the flowing of current through the tunnels. 

As the terminals corrode more, it will create an obstacle and block the current flow.

Therefore, the car will receive insufficient power. Also, the battery will not receive enough charge from the alternator to recharge, and hence, the battery will get ruined. Moreover, lack of power may cause problems to the onboard computer and cause further complications.

Can blue corrosion cause cars not to start?

The blue corrosion can reduce the current flowing through the terminals to the other electrical components of the car. If it is not cleaned, the terminals will corrode more, and the corrosion will accumulate over time. As a result, the current flow may stop abruptly.

If the current flow faces obstruction, the other electrical components will not receive enough power from the battery to operate. Also, the battery will not recharge since the battery will not receive current from the alternator. Lack of recharge will cause the battery to expire.

Moreover, the engine will not receive sufficient electrical energy from the battery. Insufficient power from the car battery will cause you to use jumper cables to start your car every time you need to start the vehicle. Therefore, the blue corrosion can cause cars not to start.

Why is there blue corrosion on my car battery?

Blue powdery stuff on car battery terminals is usual. There are various reasons why car battery terminals corrode. One prominent reason for the blue corrosion on your car battery is the leaking of the electrolyte inside the battery. Another reason could be the wear and tear of the terminals.

There are various reasons why car battery terminals corrode. Some of the reasons are:

A leak of electrolyte solution:

Damaged batteries can leak the electrolyte inside them. This electrolyte accumulates on the battery terminals of the car battery, and chemical reactions take place. 

Due to the chemical reactions occurring around the battery terminals, corrosion occurs, and blue powdery stuff forms around the battery terminals.

Leaking hydrogen gas:

When current is produced inside the battery, hydrogen gas is released. Usually, hydrogen gas is released through the top venting blocks. Sometimes, the gas leaks through the fissure where the battery post is connected with the plastic casing. 

The leaked hydrogen gas reacts with other gases and forms corrosion at the battery terminals.

Overcharging of battery:

Sometimes, the battery may get overcharged. Overcharging of the battery increases the battery temperature. Overcharging increases the temperature of the electrolyte inside the battery and causes it to expand. 

As the electrolyte expands, it leaks from the battery terminals. The leaking sulfuric acid steam causes corrosion on the battery terminals.

Chemical reaction on the copper terminals of battery:

Although copper does not corrode naturally, chemical reactions can cause copper to corrode easily. Overheating the battery can cause leaking of the electrolyte from the battery terminals. 

Electrolyte leaking will leak the sulfuric acid steam and cause it to react with copper. Therefore, corrosion takes place. The blue powdery stuff acts as insulation and should be cleaned.

Overfilled battery:

If the electrolyte is overfilled, the excess electrolyte will overflow and react with the copper or metal present in the battery terminals. This chemical reaction will cause corrosion in the battery terminals and produce a white and blue powder.

These are most of the reasons why the battery terminals may be corroded. If you observe that the battery in your car has corroded terminals, clean it as soon as possible.

What does blue corrosion around the battery mean?

If you see blue corrosion around the battery terminals, it means that some chemical reactions have taken place at the battery terminals. It can also happen due to the wearing out of the battery terminals.

Corrosion on the negative terminal will cause insufficient charging of the battery. It will impact its lifetime and cause the battery to supply low power. It also usually results in white powdery elements around the terminal.

Additionally, corrosion on the positive terminal will cause the battery to overcharge. It will cause the battery to supply an insufficient amount of energy. Corrosion on the positive terminal usually results in the formation of the blue or white stuff.

How to clean blue stuff off car batteries?

You can clean the blue stuff off car batteries by using a few household items. One example of such a product is the baking soda solution. You can also use fizzy drinks to do the task. However, you should call a mechanic over to clean the battery terminal corrosion as it is a safer choice.

If you want to clean the blue stuff off car batteries yourself, follow the steps below:

Gather the necessary equipment and inspect the battery:

Before starting, it is necessary to get ready with all the required equipment. You will need a cleaning solution, a stiff wire brush, pliers and wrench, and rags and gloves.

The cleaning solution can be a household cleaning agent such as a baking soda solution. Use the stiff wire brush to scrub away the corrosion.

Use the pliers and wrench to disconnect the battery, and use the gloves and rags for protection and cleaning.

Moreover, before disconnecting the battery cables, check for any leakage or damage on the battery casing.

Disconnect the battery cables and inspect them:

Use the pliers and wrench to disconnect the battery cables from the terminals. After disconnecting, check the battery cables to ensure they are intact and corrosion-free.

Loosen the corrosion on the battery terminals:

Apply the cleaning solution that you have decided to use. If you are using a battery terminal cleaner, apply it at the corrosion site to loosen the corrosion.

However, if you are using a baking soda solution, pour a cup of the baking soda solution on the affected area. The baking soda solution will loosen the corrosion on the terminal of the battery.

Scrub to clean the corrosion and rinse and dry:

After leaving the solution on the affected area for a few minutes, clean the area by scrubbing with a stiff wire brush. After it is clean, rinse the place and leave it to dry.

Reconnecting the battery:

Once you have cleaned the corrosion, reconnect the battery using the battery cables. Make sure to connect the terminals correctly.

If done correctly, you will have a corrosion-free battery in your car. It will work as usual and not cause any complications.

Final Thoughts

Corrosion of the car battery terminals is usual, and you can easily clean it at home. Although a little bit of it is harmless to the car, it will increase over time if left untreated, resulting in complications in the future. Therefore, you should clean the battery terminals frequently.