Dunno about cleaning circuit boards, but as for removing crud from car batteries.....not only will baking soda work, it'll also neutralize the battery if you allow any of it to get inside....so be careful!

Believe it or plotz, but warm water or even Windex do a great job of cleaning batteries....mebbe the vinegar or ammonia in some Windex-like products is the culprit in this case.

Anthony