My voltage regulator in my engine computer would allow 14.9v, but the range it allowed was 13.7 to 14.9v
14.9 being too high and often it would choose 13.7 when battery was still far from fully charged had me bypass this voltage regulator and add an adjustable one with potentiometer on dashboard next to voltmeters whose voltage sense lines are right on battery terminals.
So I choose, and generally leave it at 14.4v until I know battery is fully charged or battery is above 87f, then I lower it
I understand the gauge reading different is a red flag to you. I'd double check the gauge. and the connections on back of alternator and firewall grounds.
And get a can of Caig Deoxit d5 spray for any connectors you open. no other electrical contact cleaner comes close. The presence of dielectric grease does not mean the conducting surfaces are 'just fine', as so many people seem to think.
