Have you ever gone to start your car and heard a clicking sound? Or maybe you’ve noticed corrosion on the terminals of your battery? If so, then this blog post is for you! 

We’re going to look at why car batteries corrode, how to avoid them, and how to clean them up. Let’s get started!

What is Battery Corrosion?

Battery corrosion is a common problem that occurs with lead-acid batteries when the volatile chemicals or gases inside a battery escape and come into contact with the metal terminals. It is usually characterized by a brown, white, or blue/green residue on the terminals. 

This buildup is caused by lead sulfate crystals that form on the battery plates when the battery is over-discharged or left unused for some time. It can have a serious impact on the battery’s ability to start and can interfere with the electrical current.

Causes of Battery Corrosion

Battery corrosion is caused by a variety of factors. Overcharging, mixing of acid and other materials, interference with electrical current flow, and overheating are all common causes of corrosion. 

In this section, we’ll look closer at each of these potential causes and discuss how to avoid them in order to keep your car’s battery functioning properly.


When it comes to battery corrosion, overcharging is one of the most common culprits. This happens when your alternator makes more electricity than you need, which overcharges the battery. 

As long as the battery keeps getting overcharged, it will keep giving off hydrogen gas, which is corrosive. This will cause the positive terminal of your car battery to rust. 

Additionally, this overcharging can also cause a mixture of other materials and acids, which can worsen the corrosion. 

Therefore, it is important to regularly check your alternator for any signs of wear and tear and to make sure it is functioning correctly.

Mixing of Acid and Other Materials

One of the main causes of battery corrosion is the mixing of sulfuric acid and other materials. 

The sulfuric acid present in the battery reacts with lead alloy plates and other materials inside the battery to create a corrosive substance. 

This corrosive substance is then released in the form of hydrogen gas, which can mix with other materials near the battery terminals. This mixing leads to a buildup of a white or gray powdery substance that can corrode your battery terminals and ultimately affect your battery performance. 

To prevent this from happening, it is important to make sure that your battery connection is sealed airtight, to prevent any hydrogen gas from escaping and mixing with other materials.

Interference with Electrical Current Flow

When it comes to battery corrosion, one of the causes is interference with electrical current flow. 

Corrosion makes electrical contact poor and resistance high, which means the battery has to work harder to get power to the starter motor and the alternator has to work harder to charge the battery. This can prevent your car from getting the juice it needs and prevent the flow of electricity. 

If the cables have any sort of problem, it may interfere with their ability to conduct power. Starting a vehicle takes a considerable amount of energy and if left unchecked, corrosion can affect the lifespan of car batteries.

Electrolyte or Electrolyte Vapors

Another common cause of battery corrosion is the leakage of electrolytes from cracks or loose joints. This can happen when the battery is overused or left for too long. 

Electrolytes are a combination of water and sulfuric acid, and when they leak, they can corrode the metal parts of the battery. When vented electrolyte vapors circulate around the engine compartment, they can cause corrosion as well.

The risk of electrolyte spilling onto the terminals is greater in batteries that need to be topped up with water on a regular basis. 

It’s important to check your battery regularly to ensure that it’s not leaking or corroding.

Hydrogen Gas

Hydrogen gas is one of the most common causes of car battery corrosion. This gas is released as part of the chemical reaction that occurs when sulfuric acid is present in a battery. When the hydrogen gas is trapped under your hood, it can react with the heat and cause corrosion to your battery terminals. 

This corrosion can be seen as a white-blue or greenish powder that gathers around the positive and negative posts of the battery. 

To prevent this from happening, it is important to regularly check for any signs of corrosion and take steps to ensure that your battery does not overcharge.


Overheating is another common cause of corrosion on a car battery. If the battery is not properly vented and exposed to excessive heat, its temperature can rise to dangerous levels. 

This could be because the copper wires inside the cable are corroded or because the terminal is loose. This resistance will cause heat, which will be transferred to the battery and cause it to overheat. As it reaches higher temperatures, the electrolyte solution inside begins to boil, and eventually, the battery can explode and release acid in all directions. 

To check if your battery is overheating, you may want to touch the cable. If it feels hot or even warm, then you should take precautions to cool down your battery immediately.

car-battery-corrosion. signs-and-how-to-clean-and-avoid-it

Signs of Battery Corrosion

It’s important to take note of any signs of corrosion in order to prevent further damage to your car battery.

Symptoms of battery corrosion can vary, but there are a few common signs that you should watch out for. 

The white or gray buildup on the terminals or cables is the most obvious sign of corrosion.

This is usually a sign that hydrogen fumes are escaping from the battery and reacting with the air and metal.

You may also be able to smell the acidic gas, which will smell like rotten eggs.

If you notice any of these signs, it’s important to take action quickly to prevent further damage to your battery.

Prevention of Battery Corrosion

There are things you can do to keep corrosion from happening to your car battery so that it stays in good shape.

One of the most important is to make sure the alternator is not overcharging the battery.

Additionally, you can apply petroleum jelly or a commercial product to the terminals to help protect them from corrosion. 

You may also want to use battery terminal protectors, and copper compression terminals, and limit the mixing of acid and other materials.

By taking these preventative measures, you can help protect your car battery from corrosion and keep it in good working order.

How to clean a corroded battery?

To clean battery corrosion, it is important to use protective gloves, as the acid can be caustic.

Start by neutralizing the corrosion with a paste of baking soda and water or by using a battery-cleaning spray. Then, grab an old toothbrush and dip it into the baking soda cleaner, and start scrubbing the terminals. 

For tougher corrosion, you can use a commercial-grade battery cleaner or a mixture of baking soda and warm water. 

Once the corrosion is removed, you can disconnect the cables (first black, then red) and use cotton swabs or a toothbrush dipped in vinegar or lemon juice to further clean the device. 

Finally, use isopropyl alcohol to clean the device without leaving behind any moisture or residue.

Chris Miller

Chris Miller is an auto journalist who specializes in reviewing new cars and providing helpful advice on family vehicles. He has a passion for cars and enjoys sharing his knowledge and expertise with others.

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