Alternator Full fielding..??

Whatever the drop is you measure will be added to the VR setpoint. So "if" the VR is not faulty it will want to charge about 14 when warmed up. If you measure 1.5V in the drop test, it will "run" the battery at 14+ 1.5 =15.5 V

Also notice the chart and temp. The VR is temp sensitive, so when evaluating system voltage get the engine warmed up to warm the engine bay and battery and VR and get the battery "up and normalized."