high voltage

I have an RV7A with an HDX/EMS 220, IO360-M1B, PlanePower 12V Alternator (PN 99-1012 / internal VR) charging an Odyssey PC680 battery. The HDX voltage indication has been running higher than I'd expect (14.7 and .8) with a recent flight indicating 15.0 for a short period of time. I've read...