So you want to give me a hard time for a 1/2 second surge? Does that prove I'm wrong about something?
The wire from an ignition switch to energize a solenoid can vary 12 14 16 gauge. If a solenoid was not used and the high motor currents were carried thru the ignition switch, heavy cable would be needed to limit voltage drop. Since the ignition switch is some distance from battery and solenoid, the long leads connected to the switch can be of reasonable size since they conduct only a small current drawn by the solenoid switch winding. The hold-in winding contains many turns of fine wire. The pull-in windings are the same number of turns of larger wire. When the ignition switch is operated, the current from the battery flows to solenoid "S", thru the hold-in windings to ground.(back to battery). The current also flows thru the solenoid motor terminal, thru the motor windings to ground. The magnetism created by each winding adds together to form a strong pull on the plunger. In a half second this closes the circuit between the solenoid battery terminal and the motor terminal and cranking happens.
The pull-in winding operates to assist the hold-in winding in pulling plunger into the core. Once plunger movement is completed, less magnetism is needed to hold plunger to disc. Now battery and motor are connected and the pull-in winding is shorted and no current flows thru it.
So I stand by my "advice"/previous post. Using a 50 amp useless factoid to disparage a friend is not needed. These systems have operated with small wire, low actuation current, no additional relays, standard ignition switches, universal ignition switches, no fuses and without failures. Where's the beef?
I'm not discussing micro switches.
Carl: Check out that idea posted here. It looks pretty good. Not much fab and cheap. Yours is probably good also but look at that one too. I think it's a tractor start button, not sure. The overall design is compact like yours. Does not stick into engine bay much. 1" ? Maybe find a 90 deg. rubber insulator boot for the hot studs. Similar to the one's on alternators.
To fit over the ring tongue terminals and over the stud?
