Tools and Materials
Tools
- Adjustable Wrench
- Wire Brush
- Nitrile Gloves
- Safety Goggles
Battery Post & Terminal Brush (Optional)
Materials
Baking Soda
- Dielectric Grease
- Microfiber Cloths
Shallow Pan or Bin
Battery Washers
Product costs, availability and item numbers may vary online or by market.
What’s Battery Corrosion?
Battery corrosion creates a green, white or blue deposit that forms on vehicle battery posts and terminals. The flakey or powdery deposits develop when gas seeps through seams in the battery housing and reacts with air, moisture and road salt.
Small amounts of corrosion can be common, particularly on an older battery, but an overcharged or overheated battery is also prone to corrosion. Battery corrosion reduces the power the battery supplies to your vehicle and reduces the lifespan of your battery. However, if the battery is in good shape, cleaning the corrosion away is a relatively simple way to restore maximum power to your vehicle’s electrical system.
Corrosion may be a sign of a defective battery. It’s always best to have a battery tested if you find corrosion. If there’s lots of corrosion on the battery and battery compartment or you’re not sure if the battery is in good shape, get it inspected by a professional before using it or attempting to clean it. If the battery is cracked, leaking or swollen, don’t attempt to clean it. Have it replaced.
Signs of Battery Corrosion
Residue on the battery posts (metal studs on a vehicle battery) or the terminals (clamps on the battery cables) is an obvious sign of corrosion. But even if you don’t typically check under the hood of your vehicle, there are other symptoms you might notice:
- You notice that your headlights are dim.
- You have problems with electronics like lights, cameras and power windows.
- The battery doesn’t charge properly and loses its charge quickly.
- The vehicle is difficult to start.
If left uncleaned, corrosion can eventually damage the battery and create excess wear on the alternator or starter.
Tips for Cleaning Minor Corrosion From a Battery
We’ve got general tips on how to clean battery corrosion from terminals and battery posts, but different vehicles might have different steps and precautions for working with the battery. Check your manual first and follow the battery handling instructions for your vehicle. Follow any instructions on the battery. If you don’t feel comfortable doing the work yourself, take the vehicle to a professional.
These tips apply to a standard 12-volt lead-acid battery in a combustion engine vehicle, not an electric vehicle battery.
Step 1: Protect Yourself and Prepare a Work Area
Start by dressing correctly and wearing the right safety gear. Wear long pants, a long-sleeved shirt and work boots or closed-toe shoes. Put on safety goggles and chemical-resistant gloves, like nitrile gloves, to protect yourself from any battery acid.
Cleaning a battery can be messy, and you need to have good ventilation, so prepare an appropriate workspace. Set up a shallow pan to hold the battery while you clean the corrosion.
Step 2: Disconnect the Battery
Ensure the vehicle is off, then use a wrench to loosen the bolt connecting the negative terminal to the negative battery post. The negative cable will likely be black and there should be a – symbol or “NEG” stamped on the battery case to indicate the negative post. Place the terminal so it can’t contact the post or any metal on the car. Then disconnect the positive terminal from the positive post. If there are battery washers on the posts, remove them.
Remove the battery hold-down and lift the battery from the vehicle, placing it in the shallow pan. The pan will collect the corrosion and cleaning solution. Be careful, the battery is heavy.
Before you disconnect the battery, you might want to connect an auxiliary power supply to your vehicle to maintain your clock, audio, seat adjustments and other settings.
Step 3: Clean Away Loose Corrosion
Use a small wire brush or a battery post/terminal cleaner to scrub away any loose corrosion from the battery posts and the cable terminals.
Step 4: Clean the Remaining Corrosion With a DIY Solution
You can clean remaining corrosion from the battery terminals and posts with a homemade solution made with a tablespoon of baking soda and a cup of warm water. Mix the solution and use a small scrub brush or wire brush to apply it to the battery posts. Don’t douse the battery, just apply as much of the solution as necessary. The solution neutralizes battery acid and may bubble and froth when it contacts the corrosion. This is normal.
Scrub the posts but avoid damaging the metal. Wipe down the posts with a damp microfiber cloth to remove the solution and residue. Dry the posts and battery case thoroughly with a cloth. Repeat the process with the terminals on the battery cables, but avoid getting the solution on the engine components. If necessary, clean the battery compartment as well.
Step 5: Inspect the Battery, Cables and Terminals
With the corrosion cleaned away, check the condition of the battery posts, the cable terminals and the battery cables. If any of the components are damaged or heavily worn, have a mechanic replace them as soon as possible.
Step 6: Reconnect the Battery and Apply Dielectric Grease
Carefully return the battery to the battery compartment and secure it in place with the hold-down. Place new battery washers or pads over the posts to help prevent corrosion. Place the red washer on the positive post and the green washer on the negative post. You might see some washers designated for side-post batteries and some for top-post batteries. Use the washers for your battery type and follow the installation instructions.
Reconnect the positive terminal to the positive post first, pushing it down onto the washer. Secure the bolt but don’t overtighten. Now connect the negative terminal. Once the terminals are secure, apply dielectric grease to the posts and terminals as an additional protection against corrosion. If you connected an auxiliary power supply, disconnect it now.
Some dielectric grease manufacturers might recommend coating the posts before connecting the terminals. Follow the instructions for your product.
Step 7: Test the Battery and Electrical Components
After cleaning the battery and reconnecting the terminals, turn on the engine and check the lights, sound system, etc. to ensure everything is working correctly.
Don’t pour any waste water from the cleaning process down a household drain or street drain. Check with your local municipality for disposal instructions for the material. You might need to seal it in a bag or container or absorb it with shop towels before disposal.
Key Points for Cleaning Corrosion From Battery Terminals and Posts
Knowing how to clean battery corrosion helps you keep your vehicle performing at its best and can prevent costly repairs. Follow your vehicle manual instructions on working with the battery and remember:
- If there’s lots of corrosion or you’re unsure if the battery is in good shape, have it tested.
- If the battery is damaged, leaking or swollen, have it replaced.
- Wear safety goggles and chemical-resistant gloves and work in a well-ventilated area.
- Disconnect the negative terminal and keep it from contacting the battery or metal on the car.
- Disconnect the positive terminal, remove the battery and set it in a shallow pan.
- Scrub away corrosion from the posts and terminals with a wire brush and then scrub the components with a solution of baking soda and warm water.
- Dry the battery and cable terminals, install anti-corrosion washers and then reconnect the positive terminal, followed by the negative terminal.
- Apply dielectric grease over the terminal and exposed post.
- Start the car and test the electronics.
Shop Lowes.com for the tools and materials you need to clean corrosion from your battery. From safety gear to protective dielectric grease, we can help with your project. If you’re not sure what you need, stop by your local Lowe’s and talk to a Red Vest associate. They can help you find everything you need to keep your battery and vehicle in top shape.
FAQ on Cleaning Battery Corrosion
If you have questions about recognizing corrosion and cleaning it from your vehicle batteries, these answers can help.
What Are the Deposits on My Car Battery?
White, green or blue deposits around the posts on a vehicle battery or the cable terminals are most likely signs of corrosion, where gas escaping from the battery has reacted with air and moisture. A small amount of the material is normal, particularly as a battery ages, and relatively easy to clean. If there’s lots of corrosion or the battery appears swollen, have the battery replaced as soon as possible.
What Problems Does Battery Corrosion Cause?
Corrosion keeps the battery from fully powering your vehicle and the onboard electronics. Left in place, corrosion can cause problems with electronics, reduce headlight brightness and make a vehicle hard to start. In some cases, it can damage the battery and lead to premature wear of vehicle components.
Is Battery Corrosion Normal?
While minor corrosion can be a normal occurrence, it can be a sign of a bad battery. If you notice corrosion, it’s always a good idea to have a battery tested to make sure it’s in good shape. If there’s a lot of corrosion, have the battery inspected by a professional before using it. If the battery is cracked, leaking or swollen, don’t use it. Have it replaced.