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How To Clean Corrosion Off Car Battery Terminals

By Edited Nov 13, 2013 0 0

If you've noticed your car battery running a little weak recently, there's a good chance you've got a buildup of corrosion on the battery terminals. Don't worry, learning how to clean corrosion off car battery terminals only takes a few minutes, and actually cleaning them doesn't take much longer.

But first, what is car battery corrosion and why is it bad?

Corrosion is that nasty white-and-green junk that forms on your car battery terminals and cables. It's actually the result of ongoing chemical and electrical reactions between the acids in your car's battery and the electricity that passes through it on the way to the engine, stereo and other accessories. While it's easy to spot in extreme cases (it can look like a living tumor that's completely engulfed the terminal and cable), it might be harder to notice in lighter scenarios.

Battery corrosion causes current loss and adds resistance to your car's electrical system. In layman's terms, that means that your battery won't charge up as easily, nor will it produce the normal amount of "juice." You can normally tell when you're battery is losing power during start-up, when you'll hear the tell-tale "wah-wah" of an engine struggling to turn over.

But just because you can't see it doesn't mean it's not there. In fact, I'd contribute at least 95 percent of every "battery problem" to corrosion that you can't see. Needless to say, if you're having issues with your car battery, it's always a good idea to clean the battery terminals and treat them to prevent future corrosion even if you don't see any problems on first glance.

How To Clean Corrosion Off Car Battery Terminals:

Tools You'll Need:

You don't need an industrial auto mechanic's tool chest to take care of corrosion. All you really need is a crescent wrench or two for removing the cables from the terminal, and an inexpensive battery terminal cleaner. An optional product (which I recommend) is a can of battery terminal protector to help slow and prevent the future accumulation of corrosion.

I'm assuming you already know what a crescent wrench is, but you might not be familiar with the other products I just mentioned - so let me explain.

Car Battery Terminal Cleaner
A Battery Terminal Cleaner is a handy wire brush tool that has two "business ends." The first is a socket-style orifice that fits over the top of a battery terminal. The other side is designed to clean the inside of a battery cable.

These tools cost about $4 and they're small enough to fit in any tool box or trunk.

If you don't have one of these tools (and have no intention of buying one), you can try to make do with a standard wire brush, though your results likely won't be as good.

Battery Terminal Spray
Battery Terminal Protection Spray can help protect the surface of your cables and terminals, thus preventing the future build up of corrosion. While this is optional, I'd highly recommend using it, unless you want to spend frequent time under the hood cleaning off your battery.

This spray costs about $8 per can, and will last for a very long time.

When I was in high school, I experimented with WD-40 as a corrosion prevention chemical. Honestly, it worked great. However, I'm not a chemist and don't know if this was safe. While I included this little tidbit for your reference, I would highly recommend against using WD-40 in this application unless you know for sure that it's safe.

Let's Clean Those Car Battery Terminals

Step 1: Disconnect the battery cables from the terminals. They are usually held on by a single bolt and nut and should come off relatively easily. Note: If you've got a bad case of corrosion, you might need to break some of it off to find the nut.

Step 2: Clean the battery terminal post. Using the "female" end of the battery cleaner tool, twist the tool over the terminal post - it should set right over the top. Rotate the tool several times, moving it up and down slightly with each twist. The wires inside should be scraping off any corrosion that's built up on them.

Step 3: Clean the battery cable connector. Using the "male" end of the same tool, run the brush into the eye of the batter cable, using the same twisting motion. You'll notice that one side of the cable is flared out wider than the other - that should correspond with the tool, which has a tapered brush. Make sure you use the "fat end" of the tool on the "fat end" of the eye hole. The easiest way to remember: Put the skinny end of the brush through the fat end of the hole.

Step 4: Repeat steps 2 and 3 on the other batter terminal and cable.

Step 5 (optional): Spray battery terminal protection spray on the battery terminals. Don't soak them, but make sure you spray every exposed millimeter of each terminal.

Step 6: Reconnect the batter cables to their appropriate terminals. DO NOT put the wrong cable on the wrong terminal post, you could cause serious (and very expensive) damage to your vehicle.

Step 7 (if necessary): Hook a battery charger up to your battery. Corrosion will severely limit a car batter's charging capacity and power, so there's a good chance yours is running low on juice. If you have a good battery charger, it's a good idea to hook it up and let it do some serious charging.

See, that wasn't so hard, was it?

I would recommend driving your car around the neighborhood for at least 15 minutes after you've cleaned the battery cables, as it will help refill the battery's charge. When I say "drive" I don't mean "let idle" - make sure to get the RPMs into normal driving range for a while. Why? Because most alternators (the device on the engine responsible for recharging the battery) don't operate at idle speeds, they only kick on when you've got your foot on the pedal. So letting your car idle does absolutely nothing for recharging the battery, but it does cost gas.

Note: If you used a battery charger (step 7) you can omit that last part.

As an added bonus, by clearing off all that junk, you're helping your alternator and electrical system run more efficiently, which can actually help you get better gas mileage.

Now you officially know how to clean corrosion off car battery terminals!



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