[Al Skierkiewicz]

Kevin,
You would have to get the motors up to speed to generate 12 volts in the motors. While you can get enough voltage and current to light the LEDs, I don't believe you can exceed the reverse bias maximums. Remember that the rest of the robot is also supplying a significant load to that controller when the robot is pushed. When you connect the battery, you get a low impedance, high current voltage source at 12 volts.