Jim, I've used that "trick" many times. If you live up here in the
frozen tundra it will make you a believer. I've used it successfully
on trucks, tractors, garden tractors, and the Aztec. I've haven't
heard that it makes the battery warmer, but rather that the draw
causes the battery to "wake up" and re-charge itself. Suposedly the
draw from the starter isn't long enough to "wake up" the battery.
JimB