OK, this one is for"leitmotif." Under no load the Gen. was showing 11.26 volts. I turned the lights on and it went to 10.90v. You would think the gen. was not putting out enough voltage. Read the following.
Well that is not too bad. What is more inportant is the data you reported where you grounded the field and got 16 volt.
I agree with other guy (I forget name) that gen is probably OK and you have regulatorproblem
Dan Bentler