Howto: Clean up corroded battery terminals

Every time I open the hood they're there, mocking me - my corroded battery terminals.  I've cleaned off the corrosion before only to have it come right back.  Plus my brother also points it out every time as well, and reminds me that the Grand Am never has that problem.  So last time we were at the auto parts store I noticed a packet of "Battery No Corrode Gel", and decided it was time to fix this problem for good. This gel is supposed to insulate the terminals from corrosion, and it "sets" after drying so it doesn't remain goopy like other substances people use for the same purpose (such as petroleum jelly).

If your battery terminals look like a snow man, you need to read this article!

Battery terminals corrode due to an interaction between escaping acids/fumes from the battery and the metals on the terminal connectors.  I've read that some people glue a penny to the top of the battery and it attracts the corrosion instead, which is interesting but I've never tried it.  Depending on your type of battery and other factors such as leaks between the battery case and terminals, your battery may tend to get a lot of corrosion.

The corrosion not only looks bad, but it degrades the connectors and can prevent a good electrical connection which can prevent your battery from charging cause your car to not start.

• Note: You're going to be disconnecting your battery causing a power loss to your car electronics.  Make a note of your radio presets, and have your radio anti-theft code handy as well as the codes for any other electronics in the car, such as navigation units, if applicable.

First, clean off what corrosion you can so you don't make a big mess and get it all over your fingers when you remove the battery contacts.  A solution of baking soda and water will neutralize the acid, but I thought it was easier to just suck it all up with the shop vac (which is not a generic term, when I asked for a shop vac filter at Home Depot the guy told me they don't carry Shop Vac, only Ridgid, which is what I have, but asking for a "Ridgid filter" seemed weird).

You'll need to clean off enough corrosion to be able to get to the nuts holding the connectors on.  Loosen these nuts with a wrench just enough to be able to slide the connector off.  Remove the negative terminal first, then the positive terminal (reconnect in reverse - positive first, then negative).

Remove negative terminal, then positive.  The positive terminal will generally
be color coded red somehow and should have a rubber hood over the terminal. The extra
red wire and fuse pictured is for an aftermarket amp. 

Many sites will recommend this but won't tell you why.  The reason is that you risk shorting your wrench between the positive terminal and any piece of metal on the car (which is all connected to ground) as you loosen it, possibly welding the wrench to the metal or starting a fire.  There is no such risk with the negative terminal, so you start there.  After that is disconnected, the chassis is no longer grounded.

In my case I also wanted to clean up the battery and the tray underneath it, so I removed the battery.  To remove the battery, there is generally some kind of tie down holding the battery in place.  On the TL just loosen the tie down bolts and unhook them from the battery tray bracket, then pull the battery out.

With the battery out, I wiped down the top with a wet paper towel:

Now you'll need to really clean those battery terminals and connectors.  Some people use a solution of baking soda to wipe down the terminals, and soak the ends of the connectors in.  Things seemed to be cleaning up fairly well without it, so I just used a wire terminal cleaning brush. These have a brush for the terminals on one end, and a brush for the connectors on the inside:

A battery terminal cleaning brush is a handy tool for cleaning your battery contacts.

Brush the terminals well.

Scrub the inside of the connector well until the corrosion is gone.

After you've cleaned up the terminals (and replaced the battery, if you've removed it) apply some No Corrode Gel to both the terminals and the contacts.  First you'll need to open the package, and I recommend using a knife or scissors:

Does NOT "tear here". I tried.

The instructions say to apply to all the parts then reassemble them.  It also says not to get the gel on your hands, so I used some paper towel to carefully apply it.  Then, I got it all over my fingers when I reattached the contacts.  So, whatever.

Apply to the terminal and connectors on all exposed metal.

Now reattach the terminal contacts in the reverse order, positive first then negative. Wear gloves, or just wash your hands afterward.  I wouldn't have gotten so much on my hands if I hadn't forgotten about the power wire for the amp until after I applied all the gel.

Bam! Take that Grand Am.

Now make sure your car starts and enter the anti-theft code and presets into your radio.  If the car has no power, re-check your connections and make sure you tightened everything down correctly.