Can you really pull a battery cable and the engine still runs?

Seems if your battery is already full and your ammeter is resting in the middle, then the alternator is no longer charging and it's only running any load that is on the car. In this case, the voltage spike would be minimal to non-existant. However, if you start the car and the ammeter is pushing to the far right, then I could see where pulling a cable would be bad ju-ju on the system.

I personally have never done this on the car. I always had a volt/ohm meter and would know exactly what was going on. However, I remember my grandfather decades ago saying this was how to check the alternator... but that was back in the days when the most electronics you had was a vacuum-tubed AM radio... and those radios are pretty good about momentary spikes. I sure wouldn't try it on a modern car!

I did, for the first time, do this on an old riding mower last week because I was having a charging issue. Pulled the cable and it died. It was just an old mower, so I really wasn't concerned if I messed anything up. Later found out it had some corrosion on a connector at the regulator. Fixed that, and then pulled the cable and it continued to run.