One wire alternator

OK here's the thing:

You cannot use the small contacts in the Cole Hearse to break the charging wire directly, as they won't carry the current, depending on how large your alternator is.

With the 4 terminal switch there is no need for a separate charging wire back to the rear. You can just tie it in up front to the main cable.

The reason for the relay is that you MUST break the ignition circuit. Remember the old wives tale, where you can SUPPOSEDLY check an alternator by disconnecting the battery on a running engine? Same thing here. If you wreck your car, and it's still running, the rescue crew cannot kill the engine by pulling the disconnect. It will still run off the alternator.

The other thing gets into "strategy" I guess. Some guys don't like the idea of having a huge big main cable that is hot anytime the disconnect is on. So this is where the Ford solenoid in the trunk thing comes in---they run a no6 or so wire for charging and ignition, etc, and then use a Ford relay to only fire up the main starting cable during cranking. But this becomes even more complicated, as you STILL need to separate ignition from the alternator in order to insure that the engine dies when the disconnect is pulled.