For the high voltage reading on your instrument cluster, that could be nothing more than a loose/dirty/corroded connection at the battery. The alternator requires an accurate charge indication from the battery and it can only get that if the battery connections are clean and tight. A bad battery connection can cause the alternator to think the battery is not charged which can cause it to keep upping its voltage output.
Don't just look at the battery connections and pronounce them as good. Bad battery connections can look fine. Physically remove both connectors and wire brush both the battery posts and the connectors themselves, then reinstall and get them good and tight. Once the connector nuts are tight, see if you can move the connectors around the battery posts with your hand which indicates a worn connector which there is a simple fix for.