Just turning power off to the alternator isn't good enough for me.
No I want to stop the alternator from turning and sever its electrical connection, with the push of a switch, because I am lazy.
Just removing the electrical load is only removing half the over all load at best. Since vehicle alternators are around 50% efficient at their peak efficiency (max amp draw for that RPM).
So most of the time the vast majority of the engine power sent to the alternator is used to beating on the air around the alternator.
This is why you want to stop it.
Then you must cut power to the voltage regulator, With the alternator stopped and the voltage regulator powered up it will still draw 2 to 3 amps. I found this out the hard way when I rewired my charging system to use the high amp output post on the alternator and put one of the wires in the wrong spot. It slowly drained my batteries.
I have seen people put A/C clutches on an alternator. Only problem with that is you put a bigger pulley on, reducing amp out put. For some applications that larger alt pulley is great. Not mine.
When I need power, really I need power.
How then?
I believe I should take the alternator, make it pivot. Install a spring to bring the alternator belt under tension. Then counter the spring tension with a pneumatic linier actuator when alt power is not required.
But that would allow the belt to fall off the pulleys.
Not unless I install a guard around the belt holding it in place. Just like on a riding lawn mower. The guard holds the belt just off the alternator drive pulley when tension is relaxed.
Since its riding lawn mower technology I think it could work.
All it then needs is a source of compressed air.
I have that at least.
How to control the air? The smartest way to do it would be non electronic. Something like this.
