Why Do Car Batteries Corrode? (7 Reasons Why)

Since a car’s functioning depends on the battery’s performance, a car’s battery is crucially significant in the automobile business.

But what if your car battery corrodes? It can no longer regulate your car’s ignition, air conditioning, and several functions. Then, it’s time to discover more about battery corrosion!

Why Do Car Batteries Corrode?

1. Hydrogen Gas Leakage Causes Battery Corrosion

When the acid in a car battery is converted into an electrical current, hydrogen gas is good to enter the battery and the atmosphere.

Then, the battery terminal corrodes due to a reaction with other environmental substances. Of course, depending on how the battery is constructed, you can identify various issues.

For example, if the corrosion is found at the negative terminal section, it was caused by the undercharging problem.

However, overcharging causes corrosion in the positive terminal section.

2. Electrolyte Leakage Leads To Corrosion

The battery’s container is strong enough to withstand the electrolyte’s pressure.

However, many circumstances exist when electrolyte leaks and causes corrosion on the battery terminals, including old batteries and inadequate maintenance.

Although maintenance-free batteries have a lower risk of leaking electrolytes and causing corrosion, it is still possible.

As a result, the terminals of batteries that require water regularly are more likely to corrode.

3. When The Battery Is Overcharged

It’s important to only charge your car battery adequately and up to a specific point.

That said, if the battery is overcharged, the average temperature of the electrolytes rises, increasing the levels of the electrolyte.

Further, because these batteries are securely sealed or filled up, the pressure of the electrolyte would rise as the volume of the battery increases.

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As a result, this pressure will induce electrolyte leakage through vents, and this will initiate corrosion on the terminals, lowering the battery’s efficiency.

4. The Reaction Of Copper Clamps On The Battery

The Reaction Of Copper Clamps On The Battery

Copper has high conductivity and is a corrosive-resistant metal; when an electrical current travels through copper terminals, copper sulfate is formed, causing corrosion.

In addition, copper sulfate could cause a bluish material at the copper terminals.

Finally, because copper sulfate is a poor conductor, you will begin to experience problems while driving your car.

5. Corrosion Is Noticed On Aged Car Batteries

It makes no difference how well you care for your car batteries; if you use them for more than five years, there is a greater probability of corrosion developing on the battery terminals.

So, since batteries have a five-year life span, their performance degrades beyond that; and you should replace your old battery with a new one.

Further, if your car’s battery isn’t in good shape, it will not just cause corrosion but will show itself in the form of decreased engine performance and problems starting the vehicle.

6. Faulty Car Battery Terminals

Inadequate or loose battery connections cause poor electrical connections and excessive temperatures.

Additionally, because of the material expansion and temperature differences between the housing and battery posts, gasses can escape and come into contact with the battery terminals.

Furthermore, the consequent corrosion will damage the electrical connection. Finally, because the battery will not receive the charge, it will die.

7. Batteries Corrode When Overfilled

The water or electrolyte should be poured into the battery until it reaches the specified limit.

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However, in cold regions, it’s ideal to fill car batteries with water, so the liquid has room to expand due to temperature changes. But, still, it’s not necessary to keep refilling the water.

That said, if the water is overfilled, there is a risk of leakage, which will damage the battery’s terminals and create corrosion.

To learn more, you can also read our posts on why your airbag light is flashing, why electric cars can’t charge themselves, and why used trucks are so expensive.


Overall, car batteries corrode due to sulfuric acid inside the battery, which emits hydrogen gas, causing the battery to corrode.

Another cause of battery corrosion is an overfilled or overcharged battery that will cause leakage resulting in damaged terminals and, finally, corrosion.

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