Razziel J

Hi All

i have strange problem on my car and need your help guys.

so about problem. i have f10 528 2010 year car and i have issue with charging voltage. some times it goes over 16 and car automatically disables most of electrical systems. display turns off. ac turns off. power assist and dsc turns off some times. so i'm watching voltage while driving and it goes down to 12.2, for some time it stays on that voltage for 5-10 min after that it goes up to 14.2-14.7 and after few seconds it goes up over 16. when reading fault codes in most units only fault codes are overvoltage. i replaced battery with new on and registered it. replaced alternator with used one and problem stays. today replaced IBS but problem still here...

what you think what i must to do/check next. i have all required software and hardware to fix the car. and till today i thinked that i had knowladge to fix any issue 

sorry for my english 