On Mon, 25 Mar 2013 20:04:47 +0000, Bill Wright wrote:

Any sort of reasonable connection between the two batteries will do to
charge.

You can't really charge a battery from another battery. It works for a
while but the recipient battery ends up still pretty well flat.

Selective quoting. Read the end of the next para:

"Making sound connections to the batteries might be the hard bit if you
want to try starting the vehicle with the flat battery rather than just
charge it's battery from the other one (will need the donor engine
running)."

--
Cheers
Dave.