Dimmed fog lights operating voltage?

[Edgingage]

Hi folks, 2011 SEL here:

 

We all know that, during daytime, with lights knob selected to automatic, the headlights AND signature/vertical/"fog" lights dim while driving.  I've heard/read some comments stating they go to 50% and other comments stating they go to 70%, but it's not always clear to me if they're referring to luminosity or actual voltage.  Does anyone know what's the actual voltage these lights dim at?

 

In other words, and specifically, I would like to know what's the minimum operating voltage the signature/vertical/"fog" lights get when operating in dimmed mode.

 

Your info is very welcome and greatly appreciated in advance.

Edited Monday at 02:27 AM by Edgingage