It's very important not to let corrosion set it in on your battery terminals. Once corrosion sets in, your car will randomly fail to start due to electrical contact being lost between battery and cable. Especially common with GM vehicles. Read on for more details.
Step 1
Go to the auto parts store, and acquire some battery terminal goo, the stuff that prevents corrosion. Usually comes with a new battery. Better yet, you can purchase some battery corrosion prevention spray.. does the same thing, easier to apply.
Step 2
Remove any rubber or plastic covers off of the battery terminals. Not the posts on top, but the terminals on the side that the cables bolt on to.
Step 3
Do you see any blue or white powder/corrosion forming anywhere? If no, put the covers back on and crack open a beer, you're done.
Step 4
If yes, you see corrosion, then you've got work to do. Remove both battery terminals with a socket wrench. Make sure you remove the NEGATIVE (black) cable first. Please watch what you're doing here. Don't short circuit the red terminal to any metal part of the engine or your going to be sorry. Just be cool when you ratchet the wrench back and forth.
Step 5
Get a wire brush and scrape off all the corrosion crud from the bolt, the cable assembly and the battery terminal itself. Get inside the threads of the battery female connector. Make real sure you get all the crud off the cable assy, including the connectors. I have had to cut off the rubber insulation so that I could get all the corrosion off. Just make sure to cut the rubber so that you can put it back on later. Tip - pour boiling water over the corrosion before starting any other cleaning - it will dissolve much of the deposits and wash them away. Wash down thoroughly with plenty of cold water afterwards.
Step 6
Check again to make sure you've got every last bit of corrosion brushed off. The corrosion is battery acid that has reacted with the air and metal. If you don't get it off, it continues to react and cause problems. In fact some say it will slide down the cable assy insulation and force you to replace the whole assy at considerable cost.
Step 7
Once everything's hunky dory and spotless, then spread the goo or spray all the mating surfaces completely.
Step 8
Now you're ready to put it all together. Don't over tighten and strip the battery threads... it's only soft lead after all. Put the positive (red) on first, then the negative (black).
Tips
- You may have to reset your clocks and radio presets, since all battery power was lost.
- If your car doesn't start after running fine just hours before, it may be this problem. Usually it happens with an older car with an older battery. Just putting in a new battery without cleaning the cable connectors corrosion sets you up for the same exact problem all over again! That corroded material just keeps eating away forever, if you don't get it all. Don't be lazy, do it right, and you should be good to go. A good dusting with baking soda occasionally, neutrulizes the battery acid. The red and green felt washers from the auto part store for post batteries are useful and help ID the polarity better.
Warnings
- Watch out with sparks when attaching the positive terminal back... if you have an old battery that is leaking hydrogen gas from the cells, then a spark might cause a little flash-bang, and that won't do your eyebrows any good. Make sure there is plenty of ventilation, and as always wear good eye protection during the whole job.
- Do not wear a watch especially with a metal strap or bracelet while working on a battery. Shorting the positive terminal to ground or chassis anywhere with your watch strap will cause it to become red hot very quickly and badly burn your wrist at the very least. This applies also to any other metal jewelry such as rings etc.
- Do not touch the white powder or corrosion with bare hands. The battery acid can and will start eating through your skin. If you do touch it be sure to wash your hands right away - Once you feel it, it's often too late.
