I'm using a 200 amp 3G from PA so I don't see much of a drop when the fan kicks on. I'm using the high speed wire (yellow stripe, not orange) on the taurus fan so it really moves some air.
I do see the volts go from about 14.2 V to 14.0 when the fan is on. So there is a difference.

Gotta love a 3G/Taurus fan combo.

Now I just need to figure out how to hook up a LED to show me when the fan is on. I'm not good at electrics so I have no idea. I need a tech article to show me.