When you turn the ignition key to start your car and absolutely nothing happens, you’re first thought is always of a dead battery. Something has happened to drain it such as leaving a light on. But if you pop the hood you might find that the culprit is a greasy, dirty, or corroded battery terminal.
Battery Terminal Corrosion
The problem arises more often if you don’t drive your car regularly. When the engine is not running and the battery is sitting, the terminals oxidize at a faster rate. This means you need to check the battery terminals more often for corrosion. Corrosion appears as a white, ashy deposit around one or both battery posts. Sometimes there is also a bit of color mixed in. These deposits are the result of one of several possible chemical exchanges involving vapors and the battery post.
How to Clean Car Battery Terminals
- A combination tool – battery post brush and battery clamp brush, obtainable at any auto parts store, or online. These generally come in two designs, one employing wire brush elements and the other using two cutting blades and a reamer. Though old pros prefer the latter, either will work and either is suitable if you’re not cleaning battery posts on a daily basis.
- Locking pliers (vice grips).
- Baking soda.
- Clean, lint-free cloth.
- Grease or petroleum jelly.
- Remove the battery cables from the battery terminals by loosening the nut on each cable clamp. Once they are loose, always remove the cable clamp from the negative terminal first. It’s marked with a minus (-) sign; the positive terminal has a plus (+) sign. Reverse the procedure, positive first, negative second, when replacing the cables. The cable may not come off easily. You will have to wiggle it and lift it upward until the clamp comes off the terminal post. Sometimes, especially if there is a lot of corrosion, you may need the assistance of pair of locking pliers. Be careful not to short any tools you use against the car when they’re in contact with the battery.
- Examine the battery cables and clamps for excess wear or corrosion. Should damage appear extensive, replace the cables and clamps to avoid future problems.
- Check the battery case for cracks and the terminals for damage. If you find either, replace the battery.
- Secure the loose cables so that they don’t accidentally flop back onto the terminals.
- Pour some baking soda directly onto the posts.
- Dip a toothbrush in water and use it to scrub the baking soda into the terminal posts and cable clamps. Skin and eye protection is recommended.
- If the toothbrush isn’t doing the job, Use a battery terminal cleaner brush on it. Also shine up the insides of the cable clamps by using the clamp cleaner that usually comes attached to the terminal brush or use a plain, soap-free steel wool pad.
- Dry everything off with a clean, disposable, lint-free rag.
- Smear grease or petroleum jelly on the posts to slow down the formation of corrosive deposits. Cover all exposed metal surfaces on the battery posts, battery cables, and clamps.
- Replace the positive clamp first and then replace the negative clamp. Tighten them down with the proper sized wrench.
- Replace the rubber boot or plastic shield that covers the positive terminal. If you don’t have one, go and buy some from your local auto parts store.
Penny on Battery Post?
We have heard of a trick of using pennies placed on top of the battery, one held in place with a drop of oil near each post. The copper supposedly draws corrosion off the battery terminals. We don’t know whether this works or not – if you know, please let your fellow readers know using the comments at the bottom of this page.