Battery Charger

On my Buick Enclave, 2008, I notice a few things regarding the panel
volt meter while driving.  About half the time, after starting the
engine, the panel meter goes to a position (let's say at the 2:00
o'clock position, 14.5 vdc using my DVM) then settles to the 3:00
o'clock position within 5 or so miles, and at that point measuring
13.1 vdc.  I figure that's about right for a trickle charge. (I take
these meter measurements when arrive in my garage.)

The other half of the time, the meter sits at 14.5 vdc for hours.  As
an example, on a 125 mile trip I made on  Christmas, the meter sat at
14.5 vdc all the way and I would have thought it would have gone to
the 3.1 vdc trickle charge after a short while.  Other times when I
drive 40 miles to the neighboring town, the meter never goes to the
3.1 vdc point and hangs in at the 4.5 vdc point.

My question is, would a continuous charge at 14.5 vdc cause any
overcharging resulting in a shorter battery life?

The operation conditions are daytime, no headlights or any other
accessories, radio and gps on and no other things running except what
is required to operate the car.

My knowledge is a little thin on these matters.

I am probably over analyzing this (a little too wordy) but I thought
I'd ask.

Dave C.