This is actually pretty simple, really.   As car batteries charge, they
generate hydrogen gas.  In practice, they should always be treated like
there is hydrogen gas (flammable - remember the Hindenburg?) floating around
them.

Now the IMPORTANT thing is not only that you attach the cable to the car
frame, but also that it is the LAST of the four connections that you make.
This way, when you complete the circuit, if there is a small spark, it will
be somewhere AWAY from the source of the hydrogen, the battery.

I have seen a battery explode like this and it is not pretty.  (Thank
goodness no one was hurt)

Brent Christensen
'89 GL Syncro Westy
Santa Barbara, CA

-----Original Message-----
From: Woody Halsey [mailto:WoodyHalsey@COMPUSERVE.COM]
Sent: Monday, February 07, 2000 1:27 PM
To: vanagon@GERRY.VANAGON.COM
Subject: battery explosions + a theory

Dear List,

Yesterday I caught only the tale end of Prairie Home Companion, at the
point when Garrison Keillor was talking about his automotive need to jump
start his car again and his psychic need to reassure himself by
reconfirming that it was indeed "positive to positive and negative to
negative," much to the exasperation of his interlocutor and savior.

My questions: why, according to Haynes and everyone else who knows,  should
he have in fact attached the negative end of the jumper cable not to the
strong battery's negative post, but to its ground on the frame; and why
(and how) do batteries improperly jumped sometimes explode?

My theory: members of this list are disproportionately fans of Garrison
Keillor and PHC.

Looking forward to hearing your thoughts on both the questions and the
theory.

Woody