C230sportdude19

Hi all, i just got my alternator replaced yesterday by my mechanic because it would make this horrible whining noise when driving. Got a new one installed and the noise disappeared. But this afternoon i was checking the voltage numbers in the engine menu and the numbers would go up and down like crazy! If i drove the car at speed it would stay at 14v-14.5v but the moment i would pull over at a stop light the numbers go up and down like crazy, sometimes going as low as 12v and the car kinda trembles a bit not sure if related. My car had issues starting today at my works parking lot. Managed to get it to start after a bit. Not too familiar with these types of things so I'd thought id ask to hear opinions. Wont see my mechanic till next week. I will post a video maybe give you guys an idea of what i mean. Is this normal?

https://youtu.be/mGrEfvuomDs

efzauner

not totally unheard of that a replacement alternator has a faulty regulator. Not sure where you go it and what warranty or who installed it.