How to Clean Battery Terminals for At-Home Auto Maintenance

At some point or other, most car owners will need to learn how to clean battery terminals if they don’t already know how. A vehicle won’t start without a functioning battery, so it’s important to inspect it for signs of battery terminal corrosion about once every 6 months. Car battery corrosion is relatively easy to spot: It appears as a white, green, or blue crust on the battery terminals and terminal connections.

This battery corrosion build-up is typically created when hydrogen gas is released from sulfuric acid inside the battery, at which point it reacts with gasses and moisture in the air to produce a corrosive film or crust on the battery terminals. If battery corrosion isn’t cleaned, it can reduce the electrical efficiency of the battery post terminal’s connection to the vehicle. Severe battery corrosion can even cause electricity from the battery to take a different path than intended, leading to a transient current flow carrying electricity back to the battery through parts not designed to carry it.

To avoid damage to your car’s battery and electrical systems, follow these straightforward steps on how to clean battery terminals.

Project Overview

Working Time: 15 minutes
Total Time: 30 minutes
Skill Level: Beginner
Estimated Cost: $5 to $10

BEFORE YOU BEGIN

Testing the battery, charging the battery, and cleaning corrosion on car battery terminals are relatively straightforward maintenance tasks, but it’s still important to keep in mind that batteries can be dangerous. The most obvious risk that a corroded battery poses is accidental electrocution. When removing the battery cable ends, make sure to remove the negative clamp before the positive clamp; when you reconnect the cables, connect the positive clamp before the negative clamp.

Car batteries contain sulfuric acid, a chemical that can cause serious chemical burns if it comes in contact with your skin, which is why it’s necessary to wear protective gloves and eyewear when working on or around a corroded car battery. Smoke, sparks, flames, or other ignition sources can also cause a battery to catch fire or explode, so make sure all potential ignition sources are removed from the area before cleaning the battery.

STEP 1: Locate the car battery and look for corrosion.

The battery is usually easy to spot when you open a vehicle’s hood. Look for a large black or gray box with one black and one red plastic or rubber cap. When you find the battery, closely inspect it and the battery terminals for any signs of damage, wear and tear, or corrosion buildup. If there are any significant signs of damage to the battery, like a crack in the body of the battery, then it’s recommended to replace the entire car battery.

Lift the plastic covers off the battery terminals to inspect the condition of the connections. If you see a white, blue, or green crust on or around the battery terminals, it’s definitely time to clean the corrosion off of them.

STEP 2: Disconnect the negative and positive clamps.

Before cleaning battery corrosion, disconnect the car battery from the vehicle by first removing the negative battery terminal clamp, which should be marked with a minus (-) symbol. Depending on the vehicle, you may need a screwdriver or socket set to loosen the negative clamp before removing it from the battery. After removing the negative clamp, you can safely ‌remove the positive clamp, which should be marked with a plus (+) symbol. If you are using any metal tools, make sure that they do not touch the car frame or any other metal while they are in contact with the battery.

STEP 3: Prepare the battery terminal cleaning solution.

With the battery terminals exposed, get your battery terminal cleaner ready for use. For store-bought solutions, simply read and follow the manufacturer’s directions. Alternatively, you can create a baking soda paste by combining three tablespoons of baking soda with one tablespoon of distilled water. Stir the ingredients together to combine into an effective DIY battery terminal cleaner.

STEP 4: Apply battery cleaner to the terminals.

Apply the DIY or commercial solution to the battery terminals with an old rag or wire brush. Allow the solution to sit for 5 to 10 minutes, or as indicated by the product label. Wearing protective gloves, glasses, and a mask to avoid health and safety hazards, use a wire brush to gently scrub the corrosion away from the battery terminals and clean the cable connections.

STEP 5: Rinse and dry the clean battery terminals.

When the battery terminals look relatively clean and free of corrosion, carefully rinse them using water from a spray bottle or wet cloth. Don’t just pick up a hose and spray the entire engine, though—that could cause further problems. After rinsing, use a dry cloth or towel to dry the battery, battery terminals, and cable terminal connections, ensuring that the battery terminals are completely clean and dry before proceeding.

STEP 6: Reconnect the positive and negative clamps.

To prevent car battery corrosion further down the line, apply a thin layer of petroleum jelly onto the clean battery terminals before proceeding. Then, reattach the positive cable to the battery first, and tighten it to ensure it is securely connected. With the positive cable firmly in place, you can now safely reattach the negative clamp to the negative terminal on the battery and tighten the connection as needed. Replace the rubber or plastic caps on both terminals.

To test if the repair was successful, simply turn on the vehicle. If it starts without an issue, then the battery terminal cleaning was a success.

Final Thoughts

The car battery plays a critical role in a vehicle’s function, so it’s important that the battery terminals are kept clean and free of corrosion. This simple maintenance step makes it easier to charge the car battery while also increasing the life of the battery, so DIYers can keep more money in their wallet, instead of prematurely investing in a new car battery. Just keep in mind that there are significant dangers associated with car batteries, including exposure to sulfuric acid and electrical hazards. Always proceed with caution when cleaning battery terminals to avoid injury.

While cleaning, you may also find that a battery terminal replacement is necessary if the terminal connections on the positive and negative cables are bent, warped, or otherwise damaged. This is as simple as swapping them out after safely disconnecting the existing cables and terminals from the battery, and consider applying a light layer of petroleum jelly to the new car battery terminals to help prevent corrosion.