So I know this thread is older but I have had a similar problem. I have a 96 Gsx that had the exact same problem. Battery not charging, 12 volt low etc. Put my meter on it and 12.x when off and something stupid like 190 volts when running. Unfortunately I ran it for a while without knowing. Then all of a sudden, ski would start run great then when u shut it off it would need 20 mins to start again. Replaced rectifier same problem, ended up today putting a new electrical box in the front with CDI, MPEM etc and now voltage at idle or when running is 12.8. And now problems with restarting the ski. So still now charging but at least now throwing 200 volts at MPEM. Gonna try the new rectifier again then test strator. Not sure if this helps but at least the concerns over the use of the meter is fixed. It does happen.