I can understand why people would do this with generators. Who wants to walk outside to start an engine

My alternator may not produce voltage straight away (although I'm pretty sure it does),
I am able to see an initial voltage, then a drop while cranking, then a gradual rise to a higher voltage.

I think this is nice because I should be able to use the supply leg of the 7805 to take
the voltage measurement, and need no extra wires.