[eugenebrooks]

[/font][/color]
Input welcome, could a EE out there explain back EMF for me a little better?
Matt[/color][/quote]

If one motor is over driven by the other, it becomes a generator,
in effect and saps power from the drive train to backfeed electrical
power in into the robots electrical system. This is easily demonstrated
by turning a motor by hand and watching the leds on robot control system.
You will see them light up.

If the over driven motor is sapping power from the mechanical drive
train, it is taking up power that would otherwise move the robot forward,
hence the loss in efficiency.