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How to Clean Car Battery Terminals?

Car batteries must be fully functioning in order for the vehicle to start up and continue running. If the battery is corroded, it may not be able to start if the build-up becomes excessive. Fortunately, battery corrosion can be cleaned off at home.

If you need to clean car battery terminals, here’s how:

  1. You can buy special tools and cleaners or use a baking soda and water mixture and a toothbrush to clean the car battery terminals. 
  2. Apply the cleaner or mixture to the external parts of the battery that is corroded.
  3. Let it sit for a few minutes, and then rinse with water. 
  4. Wearing protective goggles and gloves are recommended.

Batteries contain toxic acid that can damage whatever it touches or start fires. Be careful when cleaning car batteries. Continue reading to learn about what causes corrosion, the best way to clean batteries, and how to safely clean them. 

How to Clean Car Battery Terminals

Cleaning car battery terminals is a necessary task when you see corrosion. Too much corrosion will prevent your car from starting up, or it could potentially cause a fire. You can easily clean it at home with several methods.

Before You Clean

Before you begin cleaning, make sure the engine is off. The engine needs to be turned off and cooled down before you begin cleaning. If you decide to clean it after you have driven the car for a while, let it cool down completely before you get under the hood. Park in the shade and wait about an hour for the car to cool down. 

It’s possible to burn yourself when all the parts under the hood are hot. As previously mentioned, battery acid is toxic and can start fires if it gets too hot. If the hot engine doesn’t burn you, a fire just might do it.

Wear protective gear when you clean the battery terminals. If acid is the cause of the corrosion, you might be at risk of getting injured. Wear goggles, gloves, and cover your skin to avoid any contact with acid. Leaking acid may not be the issue, but it is always best to take safety precautions from the beginning, especially if you don’t know the cause of the corrosion.

Disconnect the cables from the battery. You should be wearing protective gear when you do this step. Car batteries have two cables: a positive and a negative. Remove the negative cable first by using a battery cable wrench. Put the wrench around the cable nut and turn it counter-clockwise. After you remove the negative cable, you can remove the positive cable.

Make sure you have lint-free cloths. You will need a towel or cloth to wash away the corrosion. If you don’t want to let the battery air dry, you will need a second cloth to dry off the battery. Make sure they are lint-free. If the towel leaves behind lint, you risk starting a fire when the engine starts up, and it gets hot under the hood. A microfiber cloth should work well for these tasks. 

Use Specific Products

You can use a do-it-yourself method of baking soda and water to clean the battery terminals, but there are specific products meant for this task. Battery cleaner is about $10, and a battery terminal cleaning brush is about $5. 

These tools are affordable and are sold online, and in auto parts stores, so they should be easy to find. Since they are made specifically to clean car battery terminals, you can be assured that they will get the job done. Home remedies will work, but with battery cleaner, you don’t have to make any guesses about the ratio of ingredients or how to use them.

To clean the battery terminals, spray the cleaner onto the corroded terminals, making sure to cover all the affected areas. Allow it to sit for two or three minutes, and then wipe clean with a wet towel. If that didn’t remove all of the corrosion, use the battery terminal brush or a toothbrush to scrub it. Apply more cleaner as necessary.

Be sure to follow the directions on the cleaner packaging. While most cleaners are meant to be used the same way, different brands may have slightly different instructions. Just follow whatever it says to do on the packaging. 

Be mindful when using a wet towel to wipe up the cleaner. It’s okay to have a wet rag around the car battery, but remember that water can cause the electrolyte to leak out of the battery, which will eventually lead to more corrosion. Make sure the rag isn’t dripping wet, but wet enough to remove the cleaner. 

Homemade Baking Soda Cleaner

Baking soda and water can be used as a cleaner to remove corrosion. If you choose this method, you can either use the battery terminal cleaning brush mentioned above or just use an old toothbrush. You might have to scrub harder with a toothbrush, but it will get the job done if you’re looking to use household items.

The baking soda cleaner should be the consistency of paste. You don’t want the mixture to be too runny, or it will get into the battery. There are many different recommendations for baking soda to water ratios, so you can pick which will work best for you. 

Use three tablespoons of baking soda and one tablespoon of water for a thick cleaner. For a thinner cleaner, you can use one tablespoon of baking soda in one cup of water. It’s better to use a thick cleaner so you can control where it goes, and so it will stick onto the battery terminals.

To clean the battery terminals with baking soda and water, apply the mixture to the corroded areas. Cover them thoroughly with the thick mixture and allow it to sit for two or three minutes. Then, you can begin scrubbing with a toothbrush or the battery terminal cleaning brush. Wipe it down with a wet rag, making sure not to get water into the battery itself. Repeat the process as needed.

Another method to use with baking soda is to pour baking soda directly onto the corrosion. You can either dip a toothbrush into some water and begin scrubbing or pour a tablespoon or two of water on top of the baking soda. With the latter option, the baking soda will bubble up once the water is poured. The reaction will neutralize the acidic corrosion and make it easier and safe to remove.

Let the baking soda bubble for a few minutes before you begin scrubbing. As with the baking soda paste method, you can use the battery terminal brush or a toothbrush to scrub away the corrosion. Wipe away the mess with a wet rag.

Alternative Cleaning Method

It’s said that Coca-Cola or Pepsi can be used to clean off corrosion if you don’t have any baking soda. It might work in a pinch, but it isn’t recommended since liquids around a battery are potentially dangerous. Plus, it will leave behind a sticky residue if it isn’t completely cleaned off, which can also be a hazard. As with any home remedy, you should use caution if you decide to test this method. 

To clean the battery terminals, pour a small amount of soda over the corroded areas and let it sit for a few minutes, just as you would with the baking soda or terminal cleaner. The soda will react with the corrosion and neutralize it just like the baking soda does. After a few minutes, you can begin scrubbing with a toothbrush. Rinse the area with a wet towel. Once it’s dry, make sure it isn’t sticky. Rinse again if it is.

After You Finish Cleaning

Once you complete the cleaning process and all of the corrosion is removed from the battery, let the battery dry completely. Do not try to reattach the cables while there is still some water left behind. Use a towel to dry the area or let it air dry. Air drying is the safest option since a towel can leave behind lint. Let it air dry for about twenty minutes.

After the battery is dry, put the battery cables back into place. The positive cable should go on first, then followed by the negative. Use the battery cable wrench you used to take them off to put them back on. Be sure to tighten them until they aren’t loose.

Once the battery cables are securely in place, apply petroleum jelly to the battery terminals. Put the jelly wherever corrosion can occur, including the cable clamps, the nut, and the surrounding areas. If there is exposed metal, that should be covered with petroleum jelly.

You can apply petroleum jelly before you put the battery cables into place. If you choose to use this method, you still need to make sure the battery is completely dry. Apply the jelly to all exposed metals. Then, you can put the cables back into place. As you tighten the cables, excess jelly may squeeze out. Wipe it up with a towel.

You can also use grease instead of petroleum jelly. Each one will act as a protective layer that will prevent corrosion from forming. If you choose to skip this step altogether, corrosion will form faster, and you’ll have to clean the battery more often. Greasing up the metals will allow you to go longer periods of time without cleaning. 

What Causes Corrosion?

Corrosion is the result of a chemical reaction that occurs when the fluid from inside the battery leaks out and reacts to the metal of the battery terminals. Occasionally, the reaction may happen inside the battery and leak out. If the leak happens inside the battery, you should replace it soon since it will only cause more problems later.

Corrosion can also be caused by built-up gasses. Batteries contain a sulfuric acid that releases hydrogen gas. If the gas is poorly ventilated and can’t escape the hood of your car, it can cause build-up at the battery terminals.

The fluid that’s inside the battery is an electrolyte. If water gets into the battery, it can cause the electrolyte to overflow. Once you turn your car on and it heats up under the hood, the electrolyte that has leaked out of the battery can heat up and form a gas. Just like the hydrogen gas, poor ventilation will cause it to get built-up on battery terminals.

Corrosion forms because of the reaction between the escaped liquid or gas and the metals of the battery terminals. If the substance is white, it is probably lead or copper sulfate and will turn blue when water is added to it. It’s a good idea to remember that a blue substance means it was wet at some point and that white means dry because that will help you identify the source of the problem. Remember that electrolyte can spill out if water gets into the battery, which might be the reason the corrosion turned blue.

What About Internal Corrosion?

External corrosion can typically be cleaned up, but internal corrosion usually means something needs to be replaced. Baking soda won’t be able to solve internal issues. 

The inside of the battery contains acid. The acid can leak out to the exterior if the battery is cracked. The acid is toxic and dangerous, so you should replace it immediately. 

The battery terminals can become loose, which will cause the acid to leak out. Loose battery terminals can cause the engine to catch on fire, so you need to replace them immediately if that is the source of the corrosion.

Remember that battery acid is highly toxic, so you should wear protective gear if you are handling a leaky battery. Heat may cause a fire to start, so avoid turning on the engine if you’re able to. Don’t leave it on for too long if you do have to turn it on.

How to Prevent Corrosion

Corrosion is a common problem for car batteries that is often a result of everyday wear and tear. Fortunately, you can take a few preventive measures to prolong the life of your battery.

Check the Water Level

Car batteries have water in them, and that water level needs to be maintained. Check it every few months to make sure it isn’t too low. If you need to refill it, make sure you use purified and distilled water so there won’t be any minerals left behind. Minerals can build up and cause corrosion on the terminals. Remember that too much water will cause the electrolyte to overflow, which will cause corrosion and possibly fire. 

Clean the Battery Regularly

Eventually, your battery will not power up your car if there is too much corrosion on the terminals. Create a maintenance schedule for yourself, so you can frequently clean the battery and prevent build-up. 

It’s better to clean when there is little to no corrosion rather than when there is a large pile of it. It will be easier to clean, and you won’t have to scrub as hard. Sometimes, it can be difficult to clean off the corrosion with a toothbrush, but it shouldn’t be as difficult if you choose to clean frequently.

It would be wise to clean it every few weeks or once a month. The longer you wait, the more corrosion you will have built up.

Anti-Corrosion Washers

There are washers made specifically to keep corrosion from forming on car batteries. You can find these washers at your auto parts store. They have a felt lining on the inside of them that has a formula that will prevent corrosion. Place them on the nut that you connect the cables to, and then put the cables on over them.

Using these washers and applying petroleum jelly or grease is probably the best way to prevent corrosion. It may not stop it completely, but it will allow you to clean the battery less frequently. 

Final Thoughts

Cleaning car battery terminals is a simple process. All you need are:

  • Protective gear such as goggles and gloves
  • Cleaner or baking soda and water
  • Battery terminal cleaning brush or a toothbrush
  • Petroleum jelly or grease

Make sure the engine is off and cooled down completely before you begin to clean. Wear protective gear to prevent any burns or injury from battery acid. Remove the cables, beginning with the negative.

Apply cleaner or a baking soda mixture to the corroded areas. Cover them completely and let them sit for a few minutes. They will neutralize the corrosion and make it safer to handle.

Scrub with a toothbrush or battery terminal cleaning brush. The toothbrush may be more difficult to use, but it will get the job done. 

Rinse with a wet rag. Be sure all traces of corrosion, cleaner, or baking soda are gone. Make sure the rag isn’t so wet that it’s dripping all over the battery.

Allow the battery to dry completely.
Once the battery is completely dry, apply petroleum jelly or grease and put the cables on. You can choose which step you want to do first. Make sure you put on the positive cable before the negative, and that all metal surfaces are covered with jelly or grease.

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