Lex Jenkins , Mar 02, 2011; 05:53 p.m.
I've used old fashioned ink pen or typewriter erasers to clean corrosion or heavy oxidation from battery contacts. These are getting hard to find. Last source I found for typewriter erasers was in an antique shop, of all places. They're the kind that can be "sharpened" like a pencil as the eraser wears down. Bought a bunch of 'em. They were still cheaper than the equivalents sold in a local camera shop. Pencil erasers are useless - they leave smudges on the contacts.
For light cleaning or delicate plated contacts I'll use cotton swabs very slightly dampened with isopropyl alcohol.