Thanks for the link. I will research what is over my head, but this begs the question... Can't a plug be connected to a computer to falsify the amperage signal?
It could be. The signal is generated in the first place by some kind of microcontroller device.
Specifically, say a Nissan Leaf connects to a 72 amp system, can't an interposed computer falsify the signal?
Yes. But this is hardly going to happen by accident.
Now, would that leave the Nissan Leaf open to getting fried by higher amperage OR would the Leaf be able to self regulate an only use what it needs without overloading?
The pilot signal tells the car how much current is
available from the supply.
If the car isn't able to take that much current (or doesn't want to right now due to its state of charge etc.) it will draw less.
So in your particular example, a Leaf can't draw more than 30A (depending on model), so if the true signal was saying 30A and your hypothetical box in the middle was falsifying this to read 72, then nothing would happen. If the true signal was saying something less (maybe 10A), then the Leaf would draw 30A when it should be drawing only 10A. Similarly, a Roadster connected to a 30A point that had been falsified to 72A would now draw 72A.
In a properly installed system, the pilot signal indicates the current that can be drawn safely without overloading the wiring; there should then be a circuit breaker to protect the wiring from short circuits etc., so the effect of inserting your box would normally be that the breaker then trips.
Understood and thanks. Yes, I was referring to the internal car charger and not the external Supercharger type system.
Just how is the signal encoded into the charge current?
How does the car "read" it?
I read a Wikipedia article but I don't understand yet where the signal is hidden.
Maybe you are not understanding that there is an extra wire in the cable and an extra pin in the connector to carry the pilot signal.
Note also that the pilot signal has two functions - the pulses communicate the available AC current, but the car is also required to present a particular resistance between the pilot pin and earth - the EVSE passes a current through the pilot pin and back via the earth pin/wire, and uses this to verify that the earth wire has not become disconnected.