Jump starting - which manual is correct?

Originally Posted by wild1poet2

I just saw this thread. The reason some advise connecting the negative to a ground is to avoid the situation where a spark from connecting to the negative terminal on a battery ignites combustible gases from the battery. There have been cases where batteries have exploded into peoples faces. But sometimes you cannot get a good ground a you just take your chances and connect to the negative terminal. LOL The Porsche manual also has to consider legal liability.

Ditto. That is correct. In addition, a running donor car was a must a few times I jumped a dead car. The good battery alone didn't have enough juice to turn over the car from the dead battery. I recall the alternator squealed some, and took about 3-5min to get a good enough crank. I would surmise that without the alternater, some really drained batteries would never trickle enough juice from the charged battery to start a car in some situations (very cold outside, or big block, etc...). So while I respect Jim's opinion, I don't agree with him.