Pictureman
Enthusiast
Back in my auto mechanic days (80's) we were told not to disconnect the battery with the engine running because it would tell the alternator to go full tilt and start to spike the voltage output and start doing bad things to your electrical system. It was an easy way to test the alt, because if the car died that meant the alt. wasn't working, if it keeps running the alt. is working. So if someone trys it lets us know if it causes a meltdown of some sort.