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.
Table of Contents:
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
Supplies:
- 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).
- Toothbrush.
- Baking soda.
- Water.
- Clean, lint-free cloth.
- Wrench.
- Grease or petroleum jelly.
Directions:
- 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.
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re: legality of defacing currency
to:
Thomas A Echols Jr October 2, 2007 at 12:27 am
It is not illegal to deface US currency. I can take my coins and melt them down and/or burn my bills till they are ash.
What IS illegal is defacing currency and THEN attempting to use it as currency. Haven’t you ever read the “penny souvenir” machines? They explain right on the machine why what they do is legal.
Copper Penny
Putting penny on the center of your battery does work. I have had mine on for years and the penny is corroded, but not my terminals. The trick to that is to get a penny that was before the world wars because there is more copper in it than there is today. Now a days it is mixed with a nother metal. Mine is held on with a roled peice of electrical tape
It’s the same principle as a sacrficial anode in your swamp cooler. The corrosion attacks the “weaker” metal. I don’t know about the pre war copper stuff…… Pennys are still 95% copper.
Pennies
Pre-1982 pennies are all 95% copper (with the exception of the 1943 steel cent). Post 1982 pennies are actually copper plated zinc. Not sure if that would make a difference in this case or not though.
using grease on battery terminals.
Do you really put grease on the clean battery terminals before you reattach cables?
A drop of oil
When I was a kid, There was something my dad did every time he checked the oil level in the car. He would pull the dipstick and put a couple of drops of the motor oil on each post. He never had any corrosion on the battery terminals. I never had a chance to try it cause I had a chevy with side mount cables, which my dad hated because he was a Ford guy.
Seal it up
I was told to put any grease on the terminal to ’seal’ it from the elements. I would assume oil from the dip stick would give the same short term protection thus the need to re-apply every time you check the oil. I would not suggest greasing the cable before attaching, that would most likely cause a poor contact.
grease helps conduction?
I heard that you should indeed put grease on the bare battery post before reattaching the cables. The grease is actualy supposed to help conduct electricity. Is this true?
New Battery, New Grease
I just bought a new battery, and the salesman told me that you should grease the terminals and posts to prevent corrosion. He said to put it on after everything is attached, though.
He also suggested felt washers that you put over the posts before you connect the terminals.
Together, I hope that my new battery lasts longer than my last one.
NO grease between post and cable terminal
My local NAPA guy agrees with katie Jo … do NOT put grease between the battery post and the terminal lug at the end of the battery cable before connecting the terminal to the post. Instead, simply clean the post and inside of the terminal (NAPA actually sells a $5 tool that does both jobs) to get both surfaces down to bare metal, and THEN after connecting the cable, apply grease over the post and connected terminal to reduce corrosion.
Cables stuck on terminals
My battery terminals are so rusted I can’t unscrew the wing nuts from the terminals without risquing damages. What can I do?
Thanks for any advice.
Re: stuck cables
Your best bet is to pick up a new set of terminals, whether or not you damage them.. If its already rusted, then you might have issues tightening the wing nut back (if you don’t damage it), which could lead to a bad connection. They’re cheap, only a couple bucks for a pack of two.
Sorry theres no edit button =/
I forgot to mention that as long as there is a little slack in your battery cables, installation will be a breeze. At most you’ll need a razor blade, a pair of dykes, a screwdriver, and a rachet set.
Mixing brass and lead
The positive battery terminal on my car was corroded so I replaced it with a brass terminal. The negative terminal, which was made of lead, was not corroded so I left the original one in. Does any one know if it is a problem to have one brass terminal and one lead terminal? Thanks for your reply.
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