So many people discussing how to clean the terminals, but no one mentioning the importance of a battery check.

MAKE SURE, your battery is not leaking gas at the terminal. Often, batteries develop leaks at the terminals. Make sure your battery is in good health.

Take the cables off, clean them with a battery brush, make a solution of warm water and baking soda, clean the entire battery compartment well, flush well. The baking soda will neutralize any acid that is laying around, and there is some. Re install cables, reprogram radio...

I poured a can of Coca-cola to get rid of the white deposit first (Heard it from the brothers on Car-Talk). I then flushed it with water, dried it and applied grease on the outside. It worked fine. DR Pepper works too.

disclaimer: try it at your own risk. especially, make sure the coke doesn't get into the battery, i.e., make sure the caps are closed.

Clean the battery, the battery compartment, the cables and their ends scrupulously clean. I MEAN CLEAN. Get out there with Fantastic and a toothbrush, if you have to.

Then, take some steel wool, or sandpaper, and scuff up the contact surfaces of the battery cable ends and the battery posts.

Then glop a whole bunch of grease (wheel bearing grease is the best 'cause it is the thickest and most temperature resistant and will stay where it is put compaired to other greases) on the post, before you put the cable on. Then put the cable on, tighten it up add evey more grease.

Make sure your battery is topped up with distilled water, to it's proper fill height.

Ocassionally, re-clean and re-grease the whole thing.

By the way, grease is okay between the cable end and the battery post. It will not hinder the electrical connection. If you look at just about every connector on just about every quality car made today, it is filled with silicon dielectric (that stands for insulating) grease. Good electrical connections are called "gas tight" connections because there is solid contact between the two metal services--a connection so tight that even a gas cannot pass. The grease will be displaced and, although you will not acheive a "gass tight" connection, you will achieve an excellent connection and the grease will protect the connection into the future.

Ken

Auto parts store sell a special wire brush. Basically, a short
pipe with wire brushes on the inside that clean the terminal.
You can also get some little felt pads that go under the post
to reduce corrosion.

Example of a cleaning brush:

http://www.vehicle-wiring-products.co.uk/VWPweb2000/photos/1450.jpg

(that one looks a bit fancy, I've seen simplier ones that are
probably cheaper.)

I have also seen many posts here about battery cable corrosion so
check both ends of the cables in case they are corroding at the
other end, too (disconnect at the battery to do this).

Don't forget to wear safety glasses when working around the battery :)

A wire brush to get rid of all the gunk on there (dont' touch it with your hands...if you do, rinse thouroughly with water). Then sand down the posts to give a clean contact patch.

Put some vaseline or grease on the posts to keep them off, and you should be set