I am pretty sure I solved my overvoltage issue.  I drowned the alternator with electrical contact cleaner and after it dried I started it up.  Voltage was now reading 14.0-14.2 volts and it stayed that way throughout a couple of flights.  That is down from 14.5 to 14.8 volts which was setting off the alarm on the previous flight (verified with 2 volt meters).  I tried that based on a hunch after realizing the voltage issue came up about the same time as a renewed oil leak in the turbo oil return line.

 

The good thing is that it finally made me get around to re-installing a proper alternator field switch and is going to keep me more on top of any oil leaks that pop up.

 

BTW, that spray can electrical contact cleaner is great stuff.  Four years ago it also put the magic smoke back into my flap motor and it has worked great ever since.