So about Vin on the Motor Control Shield...
I understand that you can use an external power supply on these screw terminals to power both the Arduino and Motor Controlling. And by cutting the Vin enable on the back, you can make that power input power just the motors, and not the Arduino, however I can't seem to get it to work?
I'm building a small robot and couldn't get enough power to the motors to drive over carpet. I prototyped a new setup where I provide 6v to the Ardiuno and 12v to the Motor Control Shield. I have two four-AA trays in series with each other, which should give me 12v, which is connected to the Motor Shield. After attempting to cut the Vin enable several times, I kept getting continuity across the two pads, so assumed I hadn't successfully disconnected them. Knowing this and not wanting to damage the Arduino with 12v, I simply bent the pin coming off the shield so it wouldn't connect with the Arduino.
To get things going, I powered the Arduino off my USB connection and the motor shield off the eight AA in series. I wasn't able to get any motion on the motors though?? One set of batteries got warm, the others stayed cool. I'm pretty sure I have the trays wired correctly (Motor Shield GND to tray-1 black, tray-1 red to tray-2 black, tray-2 red to Vin).
Am I doing something wrong??