If your car or truck is having a hard time starting, or if it’s not starting at all, check your battery for corrosion. Battery corrosion is a natural part of using a lead acid battery. When the battery gets hot enough, or while it gets charged as you drive, gas from the acid escapes through the vents or through joints or cracks in the case. The gas reacts with the metals that the battery post and cable are made out of, causing battery corrosion. The buildup of battery corrosion around your posts can disrupt the flow of electricity from the battery to the cable. Since the cable is what carries the power from the battery to your car or truck, this can stop you cold.
The good news is that it’s not hard to clean up battery corrosion. Below is a step-by-step guide to do it. Here’s what you’ll need:
Tools to clean up battery corrosion
- Some gloves to protect your skin. Rubber, latex, or nitrile gloves work best.
- Safety glasses to protect your eyes. Choose a pair that’s not shaded—It can be dark under the hood.
- Brushes. A toothbrush, wire brushes, and a battery terminal cleaner all work well.
- Baking soda. Might as well get a box to keep around the garage in case of future acid spills.
- Water. Works best when it’s hot. Distilled water is preferred.
- A cup or some other container. A measuring cup works nicely. You can mix the baking soda and water in this and use it to soak the cable clamp.
- Clean, non-cotton washcloth or shop towels.
- A wrench. A ratchet with at least a 6″ extension or an extension wrench is the best for reaching down to loosen the battery mount.
- A pliers or vise grips. You may need them as you loosen and tighten the clamps on the battery cables.
- Dielectric grease or battery terminal protectant spray.
That’s all you need. So let’s get started.
Step 1: With gloves and glasses on, open the hood and disconnect the battery.
Always remove the negative “-” terminal first. This is a precaution against a short circuit. After you’ve disconnected both terminals, you’ll need to take off the battery hold-down, and/or loosen the bracket at the base of the battery that holds it in place. These can be hard to reach, but that’s why you brought a ratchet with an extension.
Step 2: Remove the battery from the engine compartment.
Set it in a place away from the car so you don’t risk the splatter of acid onto your car when you clean it.
Step 3: In your container, mix about 1/3 cup (75-100 ml) of baking soda with 2/3 cup (150-200 ml) of water.
Baking soda neutralizes battery acid and dissolves corrosion. This is what you’ll use to clean the terminal clamps and the battery posts
Step 4: Stick the end of the battery cable into the container and let it soak to dissolve the battery corrosion on it.
This may take a few minutes. If the corrosion is not dissolving, add more baking soda to your cup. After the corrosion is all gone, wipe the clamp dry with a towel or washcloth. Usually, only the positive cable and post corrode, but check them both anyway. Check the cables to make sure there are no breaks, cracks, or fraying. If you see any of these, you should replace the cable and clamp.
Step 5: Dip a washcloth or towel into the container and use it to wet and wipe the battery corrosion from your battery’s posts.
If you have a battery with vent caps, keep the baking soda solution from touching them. Since it neutralizes acid, you don’t want to get any inside your battery. If you can’t get the corrosion off with the towel or cloth, use the brushes. Be careful not to splatter any of the battery corrosion. It can eat holes in fabrics and cause corrosion on metals that it lands on. Take the time to check your battery. If you see any cracks or leaks, you should replace it immediately.
Step 6: Make sure your battery posts and cables are dry before putting the battery back in.
Red on positive, black on negative. Reconnect the negative cable last. Snug all of the bolts down tight, but don’t over-tighten them.
Step 7: Cover the terminals with the battery protectant spray or dielectric grease.
This will help keep the battery corrosion from coming back.
Step 8: Start the car or truck to make sure the battery is hooked up correctly.
If your vehicle still doesn’t start after this, you may need a new battery or have another problem. Even if it does start, you should take it in to have your battery tested. Battery corrosion can be a sign of other problems with the battery, or even old age.
As always, we recommend visiting your local auto mechanic if you’re not comfortable working on your own vehicle. A skilled, trained mechanic should be able to clean up battery corrosion.