What Causes Corrosion on Battery Terminals?

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What Causes Corrosion on Battery Terminals?

Have you ever seen some white or green-bluish powder on your battery terminals? That’s corrosion, and it could be the main culprit behind your car refusing to start. The variation in the color and the texture of the corrosion will depend on what has caused the corrosion. Regular maintenance of your vehicle is vital. Unfortunately, when washing your car, you may forget to clean the terminals causing corrosion to build up. As a result, it will have severe impacts on your vehicle, as indicated below. Maybe you are wondering if it’s possible never to experience corrosion on your battery. Chances are minimal if any since corrosion is one of the signs of an aging battery. So what causes corrosion on the battery terminal? Here are several reasons behind it.

What Causes Corrosion on Battery Terminal

Electrolyte Leakage

Do you practice regular maintenance of your car battery? Note that whenever the electrolyte gets into contact with the terminals, it will cause corrosion. So how can it get into contact with the terminals? In case of any damage to your battery, electrolyte leakage will occur. It will accumulate around your battery terminals, causing corrosion. Again, when adding water, the electrolyte may spill on your terminals, causing corrosion.

Battery Age

Despite your regular car maintenance, at some point, your battery will require replacement. One of the signs includes corrosion around its terminals and reduced engine performance.

Overcharging/Undercharging The Battery

Once you overcharge your battery, the temperature will increase. The electrolytes will expand, and due to high pressure, leakage will occur. Once the electrolytes come into contact with your terminals, corrosion will occur. Other than corrosion, an increase in temperature can damage your battery. It can also cause excessive water consumption. Overcharging affects positive terminals. Undercharging is not good either. As a result, the lead sulfate will form on the battery plate, causing your battery to fail. Corrosion on a negative battery terminal occurs when you undercharge your battery.

Overfilling The Battery

If you overfill the water on your battery, the electrolyte may spill over, causing corrosion on your battery. Avoid filling the water when the temperature is high. If you fill your battery on a cool day, the electrolytes will expand without leaking out when the temperature increases.

Copper Clamps

Another battery terminal corrosion cause is the copper clamps. Have you seen some bluish-greenish precipitates on the service of your copper terminals? That could be a result of copper clamps. As the current flows through your copper clamp and come into contact with the leaked sulfuric gas, it will result in the formation of copper sulfate. Copper sulfate will cause your terminals to have a bluish substance. Since it’s a poor conductor of electricity, you will have a hard time starting your car.

Also Read: Can A Car Battery Freeze?

Symptoms of Car Battery Corrosion

Note that the car battery is made of heavy-duty metals that have a low resistance to electricity. The cheap and the most common are lead-acid batteries. Once corrosion occurs, it affects the electrical system of your car. The signs below are an indicator that the terminals of your vehicle are corroded and require immediate servicing.

Difficulty Starting The Car

It’s frustrating trying to start your car several times, while else you need to attend to something urgently. In case that happens, corroded terminals could be the reason. If you notice that the terminal’s corrosion is not the problem, then the terminals could be loose. Corroded/loose terminals will interfere with the connection of your car. As a result, you will have challenges starting the vehicle, slow cranking, or when you turn on the key, you will hear some rapid clicking. In the worst-case scenario, the car will fail to start.

Loss Of Electrical Power

Terminals are vital components in the functionality of your car’s electric system. In case of severe damage/corrosion, it will cause a loss of electrical power. The only way to fix that is by replacing the terminals.

Corrosion On Your Battery

If you look at your battery and see some bluish-greenish or even whitish substance, the corrosion has taken place. The corrosion on the battery is a visible sign that you don’t require any help to see. If you check the end of the terminals, you will also know that it’s damaged. That’s why you need a regular inspection of your battery and deal with the signs and symptoms immediately.

Also Read: Best Car Battery Charger for Dead Battery

Ways to Prevent ​Car Battery Corrosion

Preventing the corrosion from occurring is a plus. If it has already happened, try to prevent it from accelerating. There are various ways you can achieve that. Some includes

Regular Vehicle Maintenance

If you want your battery to last longer without corrosion, have regular vehicle servicing. Avoid parking your car without using it for long or even underutilizing the battery with short trips.

Copper Compression Terminals

Copper can hardly get corroded on its own since it’s a good conductor. You already know what will happen when the currents flow in the copper clamps and mix with the linked sulfuric gas. To prevent that, get copper compression terminals. The tinned copper ensures that’s the entire clamp contacts your battery terminals.


Since overcharging or undercharging can cause corrosion, let your mechanic have a look at it. He will tune the electrical fault. The ever-running Ac or even a powerful amplifier can result in undercharging. Make the right adjustments if that is the cause of undercharging.

Anti-Corrosive Sprays

A variety of sprays are available in the market that prevents corrosion. They come in different instructions and are easy to use. If you don’t want to incur a high cost when buying the anti-corrosive spray, use home remedies. You can use coated felt pads, Vaseline, or grease as substitutes to anti-corrosive sprays.

Also Read: What Causes A Car Battery to Die Quickly?

How to Fix Battery Corrosion of Your Car

If corrosion has occurred despite all the preventative measures you have applied, don’t worry. You can still fix the problem though it’s not an easy task. Luckily, you don’t need to incur an extra cost since you can do it on your own. Below are several steps you require to take:

Gather The Right Materials

You can use various products to clean your car. Some include the baking soda-water solution and terminal cleaning sprays, among others. Some home remedies like Coca-Cola are not advisable. The synthetic sugar and the phosphoric acid in Coca-Cola can damage your engine and other components in your car. You will also require a brush, sandpaper, and a sharp knife. You need the right protective gear that includes sunglasses and gloves. If you have any jewelry, remove them first.

Remove The Battery Cables

Start by switching off the engine before attempting to work on your car. Check the condition of your battery. If the battery is swollen or has a leaking acid, seek professional help. Acid is dangerous if it spills over your skin. If the battery is okay, it’s time to remove the cable.

It’s easy to identify the positive and the negative cable due to their abbreviations. Note that whenever you are removing the cables, always start with the negative cable. It should have a (-) sign and a (NEG) abbreviation. After removing the negative, remove the positive one. It has a (+) symbol and a (POS) abbreviation making it easy to identify. It can also have a red color.

Inspect The Cables

Frayed cables are the reason behind the difficulty in starting the car. So after removing the cables check if there are any battery corrosion and any excess wear. Check if the insulation is either dried, cracked or even peeling. If the cables are damaged, replace them immediately.

Neutralize The Corrosion 

You can buy battery cleaning agents or use home remedies. Such remedies include a baking soda-water solution. Unfortunately, home remedies may not remove corrosion and neutralize acid like the cleaning agent.

One of the main benefits of using battery cleaning sprays is that they are easy to use and take less time. Note that different battery cleaning sprays come with different instructions. So before using the spray, read the instructions carefully.

If you don’t want to incur an extra cost when dealing with the copper sulfate on your battery terminals, use the baking soda-water solution. It’s cheaper and readily available compared to the expensive cleaning agents. Take one cup of hot water and mix it with a tablespoon of baking soda. Take an old toothbrush and use the solution to scrub off corrosion buildup on top of the battery. If the terminals are severally corroded, use a sharp knife or sandpaper to scrap off corrosion. Then leave the terminal in hot water for a few minutes to help dissolve any left corrosion.

You can soak the toothbrush as often as you want to help you clean the battery clamps and posts. Apart from an old toothbrush, you can decide to use sandpaper if the corrosion is in excess. You can also buy a battery terminal brush. Once the battery is clean, rinse it using cold water.


Once you are satisfied that the posts and the terminals of your battery cables are clean, it’s time to dry them. Use a clean microfiber cleaning cloth to remove any additional residue. Then wipe the terminals using a clean, dry rag.

Install Battery Terminal Protector

One way of preventing further corrosion is by using anti-corrosion pads. If you don’t have the protective pads, you can apply grease to the terminals. If you don’t have some grease, use Vaseline though it has some short-term effects. You can also use anti-corrosion sprays.

Also Read: Why Did My 12-Volt Power Outlet Stop Working?

Reconnect Battery Cables

Note that, when reconnecting the battery cables, you should start by connecting the positive cable, followed by the negative cable. Arcing may occur if you fail to remove the negative first and also reconnect it last.

Apply Battery Corrosion Preventative

Use the right corrosion preventative measures to provide the right coating on your battery terminals.

Test Your Battery

Remember, once corrosion builds up, it will affect the performance of your battery. So after cleaning the terminals, you expect the performance to improve. If you crank on the engine and discover that there is no improvement, you should consider buying a new battery.

Also Read: [Top 10] Best Battery Tester for Small Batteries

Buying A New Battery

If the battery has outlived its useful life or is damaged, the next option is to buy a new battery. You may seek advice from your mechanic before buying another battery. Once you start shopping for one, don’t just choose one for the sake. You need to check the manual of your car to know the recommended one.

Other than the manual, consider various factors before buying. Such factors include the warranty. What’s the warrant for the vehicle? Can you get a replacement for that battery within that time for free? What are the cranking amps as well as the cold cranking amps of your battery? Ensure the battery’s reserve capacity is high.

Also Read: [Top 8 Review] Best Battery for Jeep Wrangler


There are several causes of corrosion in the terminals of your battery. The battery age, electrolyte leakages, over/under charging are some of the causes of corrosion. Luckily, you can prevent corrosion or acceleration of the same at home. You can use home remedies or even buy some battery cleaning products. Some people use coco-cola, but it’s not advisable since it can harm your engine. When using the battery cleaning sprays, read the instructions carefully to help you achieve the desired results. If you notice any leakage of acid or the battery is swollen, seek help immediately from professionals. Never attempt to disconnect the cables when the engine is on. Always wear the right protective gear when trying to do any repair on your car. If the terminals or the battery is damaged, consider replacing them. When removing and reconnecting the cables, start with the negative terminal and reconnect it last. Before buying a new battery, ask your mechanic for advice. You should also check the manual before replacing the battery.

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