Where are you measuring the charge voltage? I wonder if you have bad grounds or voltage drops. Try measuring the voltage right at the battery terminal of the alternator. Engine running charge voltage at the Battery terminal at the alternator should be 14.6 volts or so, what ever voltage you have there you should have across the battery if not you have a voltage drop. With a pair of set of jumper cables attach one negative lead to battery negative terminal and the other negitive lead of the battery jumper cables to the engine block, does the charge voltage raise?
If you want to check for voltage drop I saw a youtube video that was good.
When you checked the diode pattern did you use an oscilloscope to check the diode pattern?