How To Properly Clean Battery Terminals

The Best How to Guide on Cleaning Car Battery Corrosion

how to clean corrosion off a car battery

Bare metal surfaces, electrical currents, moisture and oxygen do not mix well together. They all meet at the battery terminals of a car, especially in vehicles where the battery is located in the engine bay.

The corrosion resulting from the unity of these factors decreases the battery's life and performance. As corrosion prevents the current from flowing normally, corroded battery terminals can cause the vehicle to not start in the morning. This is because a cold engine needs a lot of power to be started. The rust and corrosion don't let the battery conduct the high-ampere current required to start the car.

On top of that, battery rust can cause an uneven supply of current, damaging the delicate engine electronics of modern cars.

But, you can avoid all that by following this guide to know what battery terminal corrosion is and how to clean it making it look and work as it did when it was new.

If your terminals are nice and shiny and the car won't start, you might need a new battery. Go to this 7 Steps Easy Guide on How to Replace a Car Battery for more information.

What is Car Battery Corrosion?

The reason car rust and car battery corrosion are so different is the presence of a unique rust-causing agent that does not typically affect the rest of the car. That is the sulfuric acid vapor produced during the working of the battery. At the high temperatures of the engine bay(250C), this vapor and all the factors described in the introduction combine to corrode the lead and copper joint of the battery terminal in a way far more different and harsh than the moisture and oxygen corroding the car's structural steel components.

As Sulfur Dioxide (SO2) and Hydrogen (H2) are gases, they evaporate from the reaction site. Water (H2O), Lead Sulfate (PbSO4) and Copper Sulfate (CuSO4) stay on the terminals. Copper Sulfate is soluble in water, and it gives the rust a light blue color which is dominated by the white Lead Sulfate.

At a solubility of just 0.0032 g/100 mL, Lead Sulfate cannot dissolve in water to form a solution and forms a paste instead. This paste dries and hardens under the heat of the engine.

The corrosion on a car battery terminal does not conduct electricity. All of the problems it causes are by hindering the path of electricity resulting in elevated battery temperatures and decreased life and efficiency.

It looks daunting, but car battery corrosion is easy to clean.

How to Remove Battery Corrosion from Battery and Terminals

Disclaimer: While cleaning a car battery terminal, keep in mind that the battery has Sulfuric acid (H2SO4) in it. It is high;y corrosive and can damage your skin. Always wear gloves and safety goggles and handle the battery and acid with care.

Step 1 – Disconnect the Battery

Any time you are working on the battery or any other electric component of the car, it is vital that you disconnect the battery from the electric circuit of the vehicle. This is because working on the system with the battery connected can lead to a short circuit. A current surge can cause the car's electronics to malfunction and can even cause a fire in extreme cases.

Just unscrew the terminal cables from both terminals and remove them from the battery to cut off the circuit and isolate the battery.

Step 2 – Inspect Battery Cables

The corrosion on car batteries can eat through the cables and decrease their ability to conduct electricity properly. Inspect them closely, and if they are showing signs of wear, you can do two things:

Cut the cable a few inches from the terminal and install new terminals on the fresh end of the cable, if it is long enough.
If the cable is not long enough, replace it with a new one.

Step 3 – How to Clean Car Battery Terminals?

Neutralize the car battery acid.
Clean the terminals.

These two are typically done in a single step. There are two methods to do this:

Use a Car Battery Cleaner

The best and easiest way is to buy a battery cleaner from an auto parts store. These products are designed to neutralize the acid and clean the terminals at the same time. The instructions for the use of these vary from product to product, but here is the general procedure:

Apply a generous amount of the cleaner to the terminals of the battery.
Let the cleaner sit for a couple of minutes to neutralize the acid and soften the corrosion.
Use a toothbrush to agitate and remove the corrosion entirely from the terminal.
Rinse the terminals thoroughly with clean water.
Dry the battery and surrounding area with compressed air or a used towel.

Use Baking Soda

Suppose you cannot get a commercial car battery cleaner. In that case, you can make do with a common household material, baking soda. As baking soda is alkaline in pH, it can neutralize car battery acid and soften the rust.

Take a glass of drinking water and dissolve two tablespoons of baking soda in it.
Soak your car battery terminals in the solution for a few minutes.
Use a toothbrush to agitate and remove the corrosion from the terminals.
Rinse the battery with clean water and then dry it with a used towel or compressed air

Step 4 – Prepare the Terminals for Connection

The above steps remove the corrosion from car battery terminals. However, you still have to remove the last thin layer of rust from the terminals. It will tremendously increase the efficiency of the electric system and the battery.

Take 80-grit sandpaper and sand the battery terminals thoroughly.
Use the same sandpaper for the terminals attached to the wires too.

Step 5 – Reconnect the Battery

Reconnect the battery wires and double-check that you are connecting them with the correct polarity. Tighten the cables so that they are snug but do not overtighten them. Battery terminals are not very rigid and easily break.

Step 6 – Take Steps to Prevent Corrosion in the Future

There's a simple step that can prevent your battery terminals from getting corroded and never require cleaning again. Apply dielectric grease on the terminals once they are in place. It is essential that you apply it after tightening the terminals. This grease is an insulator and can hinder the proper current flow if applied before the terminals are tightened down.

How to Neutralize and Clean Up Car Battery Acid

Disclaimer: Car battery acid is corrosive and gives off harmful vapors. Please exercise caution and always use personal protection equipment when dealing with it.

Suppose you happen to spill car battery acid or some leaked out of the battery and contaminated the engine bay. In that case, you need to clean it as soon as possible. This acid can eat through the car's paint and react with the structural parts of the car's body to weaken them.

Here are the easy steps to clean car battery acid:

Step 1 – Diagnose the Source

Before cleaning the acid, you need to know the source. The most common cause is an overflowing battery. Sometimes the battery can also be leaking. Make sure you find the exact cause and rectify it before proceeding with cleaning the acid.

Step 2 – Disconnect and Remove the Battery

If there is an acid spill or leak, the area under the battery must be affected. So, remove the terminals from the battery and take it out to clean the area under it.

Step 3 – Neutralize the Acid

Before you clean the acid, you need to neutralize it. You can use commercial products, but something as simple as a baking soda solution can also work. The goal is to make an alkaline solution react with the acid to neutralize the acidity. Soak the affected area with the neutralizer and let it sit for a couple of minutes.

Step 4 – Clean the Acid

Now, use paper towels or any other absorbent to remove as much of the acid as possible. Once all of it is cleaned, rinse the area thoroughly with clean water and dry it.

Step 5 – Reconnect the Battery

Place the battery back in its place and reconnect the terminals, ensuring that you are connecting them in the correct polarity.

In Conclusion

That's all there is to cleaning corroded battery terminals to get optimum electrical conductivity. Remember that the acid is corrosive and should not come in contact with your skin or the car's body for an extended period.

If doing all this is just too much for you, you can use our trade-in option to get the best price on your car and get a new one, free of all these problems.

Frequently Asked Questions

Can you clean battery terminals while connected?

No, you cannot. The goal is to clean the contact surface of the terminals on the wire with the battery terminals. This can only be done if the terminals are removed. Attempting to clean them while still connected will remove the external corrosion, with the internal corrosion remaining in its place.

How do you clean battery corrosion from connectors?

Soak the connectors in an alkaline solution, like baking soda, for a couple of minutes. Then, use a toothbrush to remove the corrosion. Once the bulk of the rust is removed, dry the connector and sand it down with 80-grit sandpaper to get a nice and clean mating surface.

What does corrosion on car batteries mean?

Corrosion on car batteries means that the sulfuric acid fumes from the battery are reacting with the metallic terminals. This leads to the production of lead and copper sulfate that accumulate on the battery.

Do I need a new battery if there is corrosion?

No, you do not want a new battery right away. Try cleaning the battery first, and if that solves the problem, you are good to go. If the battery does not perform well even after the corrosion has been removed, then you'll need a new battery.

What can I use to clean battery terminals?

You can use a commercial car battery corrosion cleaner to clean battery terminals. If you cannot get that, make a solution of baking soda and use it to clean the terminals.

How often should I service my battery?

You should check the electrolyte level in the battery every week. Clean the terminals and remove any corrosion that might be on them every two months. You'll generally need a new battery every 4-5 years.

How dangerous is car battery acid?

Battery acid is pretty corrosive. It is diluted sulfuric acid with a pH of <2. It can permanently damage your eyes and cause severe chemical burns to the skin. It is also hazardous for the metallic parts and paint of the car.