Blue powder on car battery terminals. Causes and solutions

Most of the time, when your car’s battery corrodes around terminals, you will see powder-like forming on the terminals. The powder can be white or green, but sometimes, it may turn blue. But what causes blue powder on a car battery?

The white powder forming on the battery’s terminals can be anhydrous copper sulfate or lead sulfate. Chemically, when anhydrous copper sulfate is exposed to water vapor, it will change its color from white to blue.

Of course, the battery’s terminals are always exposed to free air with moisture, a condition that will lead to a chemical reaction in the white powder.

The connectors on the battery terminals are of copper material. The battery contains sulfuric acid inside, and this acid releases hydrogen gas through the terminals.

The terminals are located openly to the free air; therefore, the ambient atmosphere reacts with leased gasses, creating a corrosive environment. The presence of salt and moisture elements accelerates the reaction process on the terminals.

When such salts of sulfate get exposed to the ambient atmosphere with moisture and copper connectors, they will form a white substance that changes to bluish and its corrosion.

Battery terminal corrosion is not suitable for the healthy functioning of the car since it may face difficulties to start the engine, low power supply on the headlights, and even poor recharging.

Mostly, corrosion on the battery terminals will typically be seen on the negative terminal. If you see such occurrences, it suggests undercharging the car’s battery. However, if the corrosion is on the positive side of the battery terminal, then it is a symptom of overcharging.

The main problem that leads to battery undercharging can be the alternator failing to provide enough time after the battery has lost the capacity to replenish. However, this can be due to vehicle demand for electrical load and concise car usage. The gasses produced will be exposed on the negative terminal, and corrosive substances will form.

Overcharging the car battery means there will be excessive gassing production. In this case, the electrolyte will experience excess heat, and oxygen and hydrogen gasses will be produced.

When reacted with other elements on the terminals, such gasses will cause corrosion. For instance, if the battery is older vented, the electrolyte will leave the plates exposed and damage them after it cooks away.

How do I get the blue stuff off my car battery?

You inspected your car’s battery and found a blue staff on the battery terminals? The bluish staff you see is an anhydrous copper sulfate that causes corrosion on the battery terminals.

To remove the blue stuff, you need an anti reaction to the substance. It is corrosion, and dealing with it can be a nuisance. Here is the safe way to remove it;

  • Step 1: Take off the connectors: Two cable contactors, one on the negative and the other on the positive terminal. Start by removing the one on the negative lead terminal of the battery.
  • Step 2: Put water in a cup and add one tablespoon of baking soda and stir
  • Step 3: Using a baking soda and water mixture, scrub on the terminal with the bluish stuff using a toothbrush.
  • Step 4: Since there will be corrosive or baking soda elements residues, use water to rinse them off—dry clean thoroughly around the terminals with a clean cloth.
  • Step 5: Apply petroleum jelly on the terminals-this will help prevent corrosion
  • Step 6: Return the cable connectors carefully; start with one of the positive terminals, then the other one on the negative lead.

However, if you remove the connectors from the terminals and realize one or both have swollen, consider replacing them immediately. This is because handling such batter is dangerous because of getting harmed by the chemicals in the battery acid.

How to prevent the appearance of blue powder in the car battery?

Over time, you have seen your car’s battery terminals experiencing blue powder from time to time. You take action and remove it, but later, you realize it still appears.

Such substances occur when the battery experiences undercharging or overcharging or other forms of corrosion. Therefore, if you know what leads to the appearance of the blue stuff on the terminals, stopping causes will keep off such issues.

Are there any other colors on a battery that cause problems?

Most individuals will associate corrosion with rust, and they may expect brown color, but this expectation should be based on the metallic materials.

Although battery terminals are made of metal and experience corrosion, the form and color of corrosion are different from other corrosion.

Battery acids produce certain gasses and charges that form corrosive substances around the terminals. Most of the time, the corrosive substance around the battery terminals is anhydrous copper sulfate or lead sulfate, which appears white but sometimes greenish or blue after exposure to moisture.


It is easy to identify that your car battery is experiencing corrosion around the terminals. When you see a white, greenish, or bluish substance on the terminals, that is a lead sulfate or anhydrous copper sulfate and is responsible for corrosion.

It is good to wipe such conditions away as your batter may not provide correct performance e of the car. From time to time, inspecting the battery life can enhance the good health of the battery.

However, you need to know what causes the bluish stuff so as you prevent it from coming in the future.

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