How to & Guides

Battery Terminal Corrosion: A Guide to Fixing and Preventing it


To ensure smooth operation of your vehicle, it’s crucial to maintain a good battery condition. A well-functioning battery provides the power needed to activate electrical components. Regular checks are necessary to confirm the battery’s functionality. Battery terminal corrosion is a common issue that needs prompt attention. Neglecting it can result in significant damage to the alternator and prevent your battery from fully charging.

Tools and Materials Required

To address battery terminal corrosion, you will need the following tools and materials:

  • Battery terminal cleaning tool
  • Eye protection
  • Acid-resistant gloves
  • Power supply or 12 volt battery
  • Cleaning rags or paper towels
  • Socket or wrench set
  • Water sprayer
  • Battery terminal cleaner
  • Battery terminal spray

5 Causes of Battery Terminal Corrosion

Understanding the causes of battery terminal corrosion is crucial for effective resolution. Here are the main contributing factors:

Hydrogen Gas Leakage

The leakage of hydrogen gas is a significant cause of battery terminal corrosion. When the battery converts acid into electric current, there is a high chance that hydrogen gas will escape into the atmosphere. This can lead to poor engine performance. Corrosion on the positive terminal can result in battery overcharging, while corrosion on the negative terminal can cause undercharging.

Electrolyte Leakage

Battery fluid leakage is another factor that can damage the battery and contribute to corrosion. When the liquid leaks, electrolyte accumulates on the terminals, leading to corrosion. This issue is especially common with sealed lead-acid batteries, but can also occur with lithium-ion batteries.

Chemical Reaction in the Copper Clamps

Although copper is a good conductor and not easily prone to corrosion, it can produce copper sulfate when an electric current passes through it. This reaction leads to battery terminal corrosion. Look out for bluish precipitate on the copper terminals, as it can indicate trouble with electrical conductivity in your car.

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Overcharging by the alternator can significantly increase the likelihood of battery terminal corrosion. It’s essential to ensure that your battery is not being overcharged, which you can check using a multimeter to measure the voltage.

Overfilling the Battery

Overfilling the car battery can result in electrolyte leakage. Always check that the battery is not overfilled. However, keep in mind that not all car batteries are designed to be refilled.

How to Fix Battery Terminal Corrosion

Baking Soda-Water Solution

You can remove copper sulfate from the terminals by using a solution of baking soda and water. Follow these steps:

  1. Turn off the car’s ignition.
  2. Remove the battery terminals.
  3. Use a brush to remove some corrosion.
  4. Apply the baking soda solution and use the brush to clean the corrosion.
  5. Clean the terminals with water.
  6. Apply wheel bearing grease or petroleum jelly to prevent further corrosion.
  7. Reattach the clamps to the terminals.


Another method is to use soda to remove residue. Soft drinks contain carbonic acid, which can effectively clean the terminals. Simply apply some soda to the terminals and use a soft sponge to remove the residue.

Cleaning Heavy Corrosion

For heavy corrosion, you can use an old toothbrush and a baking soda-water solution. Follow these steps:

  1. Remove the battery terminals.
  2. Prepare a baking soda solution in cups.
  3. Soak each terminal in the solution for about 20 minutes.
  4. Scrub off the corrosive materials.
  5. Pour soda solution over the terminals.
  6. Soak the battery terminals again.
  7. Use water to clean the terminals.
  8. Let the terminals dry or wipe them with a damp cloth.
  9. Consider using sandpaper to further clean the terminals.
  10. Apply Vaseline or grease before reattaching the terminals.
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How to Prevent Battery Corrosion

Prevention is key to avoiding battery terminal corrosion. Here are a few preventative measures:

  • Replace the car battery: If you have a leaking car battery, replacing it is the best way to prevent further corrosion. Typically, batteries should be replaced every 5 years.
  • Copper compression terminals: Use copper compression terminals that come in clamp form with tinned copper. These terminals ensure proper electrical contact.
  • Battery charging: Avoid overcharging or undercharging the battery, as both can lead to corrosion. The manufacturer provides a recommended battery voltage; do not exceed it. Use a multimeter to check the voltage if your car is experiencing idle throttling. If the alternator voltage exceeds 14.5 volts, it indicates a problem.
  • Anti-corrosive sprays: Consider using sprays specifically designed to prevent battery terminal corrosion. Coated felt pads can protect the terminals, and some people prefer using Vaseline or grease.


Your car battery plays a vital role in its performance. Battery terminal corrosion can occur due to various reasons, resulting in poor battery performance. Overfilling or overcharging the battery are common causes of corrosion. Fortunately, several methods exist to fix battery terminal corrosion, and you can also take preventive measures to avoid it. By following these steps, you can ensure that your battery operates optimally and prolong its lifespan.

OnSpec Electronic, Inc.

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