What Does Corrosion on Car Battery Mean and How to Get Rid of It

Sometimes, when you are jumpstarting your car or replacing the old car battery, you must be familiar with the car battery’s terminals. When your battery is old and has not been maintained properly, there is a powdery substance on the car battery terminal. The powder shows that the battery is corroded.

Battery corrosion causes the battery not to function at its optimal level.

The corrosion is leaking to the performance of the battery and also the lifespan. If the battery corrosion is not cleaned, it will cause problems to the car. Such issues include the starting problems or even the damage of the electrical systems in the vehicle.

What does corrosion on a car battery mean, and how to get rid of it?Corrosion on Car Battery

Corrosion is a crusty ashy substance that is formed around the ports of a car battery. The corrosion in the battery is formed due to the reaction of chemicals at the car battery’s terminals and the end of the cables. When the battery is charging or discharging, they are filled with sulfuric acid that is heated or cooled to produce hydrogen gas. The corrosion is caused by the hydrogen gas that is produced by the sulfuric acid inside the battery.

The corrosive environment is created when the hydrogen gas reacts with the external environment. 

Reasons for corrosion of the battery terminalsReasons for corrosion of the battery terminals

There are different reasons why corrosion is formed on the terminals of the car battery. The corrosions differ in color, appearance and texture due to the difference in the formation process. The following are the different causes of car battery terminal corrosion.

  • Leakage of electrolyte- when the electrolyte in the battery leaks, it will accumulate around the battery’s terminals and cause corrosion due to lack of proper maintenance.
  • When the battery is overfull- when the battery water is overfull and expands, the excess will flow out of the vents and corrode them since they are made of metals.
  • The reaction of chemicals on the copper clumps- the sulphuric gases produced from the leaking battery combine with the copper clumps in the presence of the flowing current to form copper sulphate that causes the corrosion of the battery terminals.
  • Overcharging of the battery
  •  Hydrogen gas
  • The old age of the battery

How to remove corrosion from car battery terminalsHow to remove corrosion from car battery terminals

Below are the steps that are followed to remove corrosion from the terminals of a battery.

1. Disconnecting the battery

First, ensure that the cables are disconnected from the battery terminals to avoid damage to the sensitive electronic parts of the car. The terminals are not supposed to be touched at once. First, you need to remove the clamp from the grounded terminal and then the ungrounded terminal. Removing the grounded clamp first is a safety measure that prevents damage to the electrical system by preventing the sparking caused by the positive terminal.

If the corrosion is a lot, it will be hard to remove the cables from the battery terminals. Therefore using a pair of vice grips will be of much help to loosen them. Do not put a lot of pressure on the clamps to avoid damage. Ensure that you wiggle them until they are loose and remove them safely.

2. Inspect the clamps and the cables

Check the cables and the clumps and replace them if they are corrupted or damaged. Inspect any signs of corrosion at the point where the line enters the clamp. Battery Corrosion can be built around the clamps and cables and also inside the wires. To know that the wires have been invaded by corrosion, you will see a white or Bluegreen residue in powder form. When the wires are corroded, they have to be cleaned or replaced to ensure that the battery functions correctly.

Ensure that you do not breathe the powder since it is a crystallized acid and can be harmful when inhaled.

3. Examining the battery

Ensure that you check the battery whether it has signs of damage. When you notice any issue with the battery, it is advisable to replace it with a new modern battery that is recycled. Remove the entire battery before you clean the terminals.

4. Inspect the terminals and clamp connection

To maximize the conductivity, ensure a smooth and clean connection between the clamp and the battery connection. Ensure that the terminals do not have many tiny holes or heavy scoring.

The pitting might not have a nasty look at the surface, but you might be unsure how deep the corrosion caused by the pitting goes into the terminal. If there is excessive damage, it is good to consider replacing the battery with a new one.  Otherwise, you can consult your mechanic to file back the terminals and new clamps.

5. Neutralized the sulphuric acid in the battery

Before you clean the battery terminals, ensure that you spread a small amount of baking soda into the terminals to neutralize the sulphuric acid. Sulphuric acid is toxic and can cause accidental burns. Again, the acid harms the environment and can also damage the components in the engine bay. The mixture of water and baking soda is not supposed to be used to clean the battery terminals.

6. Clean using a soft brush

Use a soft brush and gently apply water to the baking soda. As you do that, ensure that you don’t spread the water too much. When the baking soda mixes with water, it reacts with the acid in the corrosive deposits. Leave the baking soda to fizz for a few minutes to ensure there is more neutralization of acid before proceeding with the cleaning. A soft brush is suitable for this step since it carries more water than a stiff brush.

7. Cleaning using a stiff brush

Use a specialized terminal cleaning brush that is harder or any other stiff brush to clean the water and baking soda mixture on the terminal posts. Ensure that you don’t splash in case of an acid that is still active. Clean the inside and outside of the cable clamps giving full attention to the knowledge where the connection is made.

8. Do the final cleaning

When the fizzing has stopped completely, use water to rinse the battery terminals. Also, you can use a wiper or a piece of cloth to wipe the mix. Ensure that the mixture does not touch your skin or material since the dilute acid can still cause burns.

9. Apply petroleum jelly on the battery terminals

Ensure that you apply petroleum jelly on the terminals of the battery to prevent further corrosion. The jelly will also ensure that it is much easier to reconnect the clumps.

10. Reconnect the battery

Once you complete all the other steps, you need to reconnect the battery to complete the cleaning process. The reconnecting is done in the reverse order of how it is disconnected. The cable is connected to the positive terminal first and then to the negative terminal. Once you have joined, you can still add another petroleum jelly.


To conclude, when you notice any problem with the functioning of the battery, for example, poor connection, etc., ensure that the first option before you consider replacing it is cleaning the corrosion and applying protective grease or washer to prevent further decay. If the battery corrosion still appears within a few days or weeks after cleaning, it is advisable to consider buying a new one.

Identifying battery corrosion and getting rid of it is easy, as explained in this article. Again, when cleaning the battery corrosion, ensure the products you use for cleaning and protection are ideal for your car battery.

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