Battery Measures 15.5 vdc

I have a 1968 Dodge Dart 270, SL-6. Very nice 2 DR H/T and totally restored.

Here is my question. My battery voltage while the car is idling is 15.5 Vdc. This seems high. VR is the "new type" solid state like the old VR-101 style w/ IGN and FLD markings on the black cover. Alternator squeals a bit so will be replaced next week. Alternator is also original

What voltage should I measure at the battery???. ALT meter is slightly to the right when driving. With lights ON, ALT dips just below mid point on meter.

I could replace ALT w/ new rebuilt ALT, eliminating squeal and whine. Belts are new and good tension.

Any thoughts, recommendations? words of wisdom?

Thx...great forum, great people, great experience!!!!