Sounds normal to me...shouldn't drop and slowly go back up though in my opionion...should pop back up as soon as you let off the trim switch. Like IBNFSHN said...check out ALL you connections, water level if possible, have them load tested. 14-16 is normal. Have to remember these are not as stable as the alternator in your car...and most do not put out near the amps. The older ones I mean...the newer motors come with alternators now.