Good long story A and C.
Many years ago, I accidentally did a similar demonstration, all be it unknowingly, in my C150. After a series of summer day flights, only a few of which required the use of the radio, I found that the radio was not working well at all, and the received transmissions were quite garbled. I finished my landing, only to find that the flaps would not retract after landing.
After testing other electrical things, I realized I had a totally flat battery, and the alternator was not working either. Without shutting down, I flew home to correct the problem.
It turned out that the alternator had not been functioning for some unnown time, but probably many hours of flying over at least a day at least. The "self resetting" alternator field circuit breaker, hidden behind the panel, had opened, and remained that way, with a bit of lint stuck in the contacts. This failure does not illuminate the "low voltage" warning light, and if your current draw is very low (day VFR) is indistinguishable on the ammeter. This odd failure, is not even mentioned in the maintenance manual trouble shooting table, so it was a hard find, once I did realize I'd had a failure.
My plane is now modified to have the same 2 amp field breaker that all of the other Cessnas do.
I've had several alternator failures since, mostly at night. My experience is that the alternators are durable enough, it's the over voltage sensors which seem to quit with no warning, and take the alternator off line. There's a fix for this too, but that is beyond the scope of this thread...
My most useful tool for such night failures: You can buy very small self contained LED/battery bulbs for decorations. They are about .5" diameter, and just over an inch long. They can be jammed into, or taped to, those handy clear plastic suction cups, pointing toward the suction side. When you want to illuminate an instrument, turn on the LED, and stick the assembly to the center of the instrument glass. They provide just enough light to work perfectly, and will provide hours of light. A few of these in your flight bag are a great idea.