one wire Alternator and voltage regulator question

REGULATOR

A regulator does WAY WAY more than just simply "prevent overcharge." It does exactly what the name says "it regulates voltage."

Automotive systems ARE NOT 12V!!!! That is correct!!!!!

A properly operating charging system when running, operates at a target max, when battery is down/ under full load, or almost no load, or extreme cold or extreme hot, somewhere in the range 13.5--15V

A warm, happy, "normalized battery" under optimum conditions operates between 13.8 and 14.2V that is, "nominal" 14V operating voltage