73 Dart Alternator doesn't show charge anymore.

Now the tricky part.
Why does the ammeter normally show zero after a few minutes of recharging?
If the alternator is supplying power at 14.5 volts, and the battery is fully charged, then is the battery at 14.5 volts?
My best answer is yes, sort of.
Once the battery is has chemicaly returned to fully charge, then a surface cahrge develops. Immediately after charging, and shutting off the engine, we will find the battery is around 13.5 Volts. That surface charge will go away over time, or if we turn a light on, it will go away quickly.