On Sunday, June 23, 2019 at 9:36:43 AM UTC-4, Xeno wrote:

But it can't tell the difference between current going to the lights and
to the battery.

It doesn't need to. All it needs to know is the aggregate current draw,
the total. That will be indicated by the voltage.


--

Xeno



The voltage regulator actually doesn't need to actually know the current period.
It just senses the system voltage and adjusts the current to the alternator
rotor to maintain the target voltage of ~14V.