relay powered voltage regulator ?

THE DIFFERENCE between sensing at the alternator stud and the battery:

The reason you want the VR to sense "at the battery" is because it is the target!!! LOL that you are trying to charge.

If you have a battery that is low, and or a too small charging wire for the size of the alternator there will be voltage drop in the charging wire under heavy load

What this means is, if the VR is properly regulating at 13.8--14.2 and is connected to the alternator output, then the battery will be seeing LESS voltage.

This is one reason I don't care for "one wire" setups for many applications.

Another reason is your loads and accessories. If they are tapped off near the battery, they will also see low voltage compared to the alternator.

The original systems WERE ALL intended to be "sensed" at the battery, not the charging device. It wasn't until "one wire" setups came into vogue that this changed.

If a "one wire" has what amounts to an oversized charging wire, there is no real problem. Someplace there used to be a recommendation chart for charging wire size for Delco "one wire." They didn't get "very big" (amps output) before stuff like a no 6 wire was specified.