So, this morning I jump started our van (kids wanted to finish
listening to a story on the CD player when we got home last night, and
a person who shall rename nameless forgot to go back out later and
take the keys out of the ignition which was then left in "Acc"
position all night).  This brought to mind a question I have long had
about jump starting.  The battery in my car starts my car immediately.
 But when I connect that same battery to another car (the one I am
jump starting), that car will not start immediately...I need to wait
several minutes with the cables connected until it will start.

My question: why is that?  I will share some hypotheses I have, mostly
for their entertainment value:

1. The resistance of the cables is too high to deliver the needed
current to start the dead vehicle.  (It seems if that were true,
someone would be out there selling uber-cables that don't have this
problem, but I don't recall seeing such cables.)

2. The dead battery is a low impedance current sink while it is
charging, sucking away the available current from the higher impedance
starter until it is charged enough to start the car on its own.

And while we are on it, why does the owner's manual suggest connecting
the negative end of the cable to the engine block of the dead vehicle
(doesn't the engine have continuity with the negative terminal on the
battery--making it simpler from a procedure point of view to just
connect the battery terminals on both vehicles)?

Thanks,
Eric
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