Wiring Problem

A....First...........do you have any loads (lights stereo etc) connected to the starter relay "big stud?" Doing so puts loads on the "wrong side" of the ammeter, causing this sort of reading


B....So far as your voltages.........
The two that really really matter and they "seem OK" is

1....With key in RUN, batt pos to blue VR or alternator field, as low as possible.

2....With engine running fast and charging, measured first with loads off and again with lights, heater, etc on, is batt neg to VR case

Both these readings should be very low or zero.

If I understand your post, they are pretty low? "Except" looks like .47--.53? If your VR is at 14.2 (let's say) that ADDS to the VR giving you a running voltage of 14.75, pretty close to 15. "Not all that bad" but still

C....You may have a sulfated or other problem with the battery. I would round up a "known good" battery and swap in for long enough to "tell"