[tmodelman]

Never have run an alt on a Model T, just the std gen. The cut-out serves to prevent battery discharge when not running the gen. Without that device, the battery would be drained to ground thru the gen.

Most folks with T gen use the Fun Project regulator, that precisely does what is inside modern alternators. It tells when to charge the battery and when to not, and it stops current flow from the battery too.

A std T gen will keep on volting the battery all the time it is turning, the cutout does not regulate. That is why back ago, most folks ran headlamps to burn off the excess current to the battery. Simple way.

Or I used to place a toggle switch in the cutout wire, and then to ground. Flip the switch when running and grounded the gen, so the battery would not cook. Pic shows the toggle switch under the dash with wires to ground out the generator while on long day tours.