Good advice Bill, you might also want to mention one important fact. The
reason car batteries explode. They produce highly explosive hydrogen as a
byproduct of the charging process. Batteries often explode when the owner
is trying to jump start his or her car. The spark from the contact of the
last jumper lead can ignite the hydrogen causing an explosion spreading
battery acid everywhere. The way to avoid this is to connect the positive
and negative leads to the battery of the donor car, at the dead battery,
connect the positive lead to the battery and then find a place far removed
as possible on the frame of the car for the negative lead. This will still
spark but it should be far enough away not to ignite any hydrogen coming
from the battery. All of us, at one time or another have had to jump a
car. How many times have you ever seen some one hook up battery leads
correctly with the last negative lead attached to the frame?

http://www.advanceautoparts.com/howt.../DSM20020301BB
..htm