[drcoastline]

One of my friends dad's owned a Sunoco when we were in school (he still does) My friend was the tow truck/jump start guy. I would go with him from time to time. The truck had a plug for the jumpers he would plug the plug in first. Then he would hook the black cable to a ground on the car. A bolt, bracket the hood hinge something but not the black terminal on the battery. Then he would connect the red cable to the battery. I asked why he didn't hook the black to the battery? He said because if you hook both directly to the battery the battery could explode. So that's how I have done it ever since.

I guess i should add that was in the 80's when the majority of batteries still had to have water added to the battery. I don't know if the theory holds true with new batteries but it works so that's what I do.