On 3/27/08 9:58 AM, in article -62dnQDV5NyzK3banZ2dnUVZ_uCinZ2d@comcast.com,

You should worry about several things with jumper cables:

1. the dead battery, if its really dead, can explode when current is applied
to it.  This is why you make the last connection somewhere on the frame as
far away from the battery as you can get.  I have not experienced it first
hand, but I pulled in to the local Honda dealer once as the ambulance was
leaving with the blinded tech who had just had the experience.  Sulfuric
acid burns can be serious.

2. As long as you don't short anything, as you say,  especially with newer
computer managed cars.  Accidentally touch the cables together and you could
be looking at a buying a new engine computer.  Accidentally connect + to -
between cars, you can be looking at buying a new engine computer.  Don't
underestimate how difficult it can be to keep the helpful idiot belonging to
the other car from just jumping right in to help and .... Oops.... Sorry
about that (then he quickly drives off if he didn't also kill his own car).

3. Be careful the cars themselves don't touch.  The ground circuit can be
completed that way.  See #1 & #2 above.

I think they try to put them on in an order that will limit the
potential for damage as the steps progress.

The last frame hookup is for spark control.  Most 'will' spark when the
last connection is made and a freshly discharged or charged battery can
have enough hydrogen gas in it to explode.

I had one explode in my face as I disconnected it after a highway drive.
 The little spark from the radio is enough to blow the top off the
battery, let alone the big spark a boost usually makes.  Chunks went
through the hood, cut up my face and totaled my clothes.  I was lucky, I
was half turned away 'as normal' when doing batteries and there was a
snowbank right there and running water 10 feet away.  Got away with a
couple scars.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
'New' frame in the works for '08.  Some Canadian Bush Trip and Build
Photos: http://mikeromainjeeptrips.shutterfly.com

Your goal is for the last connection to be made AWAY from the battery, so
the spark does not occur right next to a battery that is outgassing hydrogen.

Same reason.
--scott