Some tests need to be done.
- of volt meter on battery negative post.
+ of volt meter on + battery post - off, and running at Idle, and 1500RPM +/-.
+ of meter on the big terminal at the back of the alternator, running at Idle, and 1500RPM +/-.
Another handy one- voltmeter one lead on + battery, other on the alternator big terminal.
Need to determine what is going on.
14V running isn't too far out of normal.
The difference in voltage at the battery term vs alt term gives an indication of how much current is flowing.
At idle, the stock alternator does not put out it's full rated amps, since the RPM is too low.