On Wednesday, April 10, 2019 at 12:37:58 PM UTC-4, Ralph Mowery wrote:
In article ,
says...

It takes from about 300 amps or more to start the small engines and much
more for the large engines.

It don't think it takes anywhere near that. Typical car starter is
~1200 watts which is ~1.5 hp, so 100 amps is more in the ball park.







Sure the starter is rated for 100 or less amps while running in the
small cars. As with most all electric motors I know of, it takes 2 to
10 times the running curent to get them to start turning, especially
under load. Most in the 2 to 4 times current. Then add to that a cold
engine in the winter time will take more current to start than one in
the summer time.

The wire has to stand that 200 plus amps with out dropping too much
voltage (including the resistance of the jumper clamps).

Most of the better jumpers will use atleast # 6 copper wire, The real
good ones will be even larger wire. It just gets to a point of how big
and bulkey and expensive one wants to go.

I agree, all of the above is consistent with what I said.