Here is my "BMS" hard at work:
Crude but awesome.
Here is my latest schematic for controlling my field controller with an amp transducer:
The bit with the microswitch simply raises the signal voltage slightly when the throttle is depressed to a minimum field amperage, adjustable with "Min Current Trim". Not sure if the transducer will like that very much, but I didn't want to install a diode on the output of the transducer that will eat 0.4V off the bottom of its 2.5-5.0V output range.
I hope it works!