Voltage drops when turn on electric fan

Let me answer some questions. Yes it is an internal volt regulator, I also have a ground strap from chassis to the block and the voltage stays low even at higher RPM. One thing I forgot to mention and I am sure it is important. the last time I drove it I had the fan on low speed and when I got back the fan motor was smoking. After it cooled I had to literally manually turn the fan blades to get the motor to turn. It still turns on ok now but does not spin freely with a flick of a finger. The motor gets hot in low speed and cools down in high. Do you think the motor drag could be causing the volt drop. Sorry for the lack of info. Not much wire involved, just from starter up to switches and out to fan.