Next episode:

Got the time to work on the overcharging issue today. Did all the tests mentioned above and think everyting is ok, except still overcharging, 15 to 17 at idle, running up to 18 volts with increasing rpm !!
Went back in my thoughts when this all started. A few months back I pulled out the alternator to connect a extra wire directly to the starterrelay.
One of the bolts broke and had to drill it out of the alt and make a new thread in it. I noticed then that I slightly hit the windings of the alt while drilling out the broken bolt. Now the windings are a bit damaged, so could thát be the reason of overcharging ?? that the windings are internally short now? Just guessing..

Luigi