Do we have any electrical system guru’s on here?

[Chicagowil]

The circuit must be completed to get the Alt Reg "excited". It is possible to have an Alternator that has a failing diode that will give a "false" voltage as if it is charging but it is supplying a "ripple" DC voltage charge instead of a full rectified charge. That can also damage your other electrical devices (such as a fuel pump). They are not designed to run on voltage with an "AC" component.

The original generators required a mechanic to "flash" the field to get the right polarity for the generator to charge correctly. Many a generator was installed and replaced because "shade tree mechanics" did not understand this concept.

The alternators with an internal voltage regulator need to sense the charging needs to establish its charge effect. Thus the connection after star- not the "ACC" feed.

Thom