[Al Skierkiewicz]

Jim,
The trouble with this is your controller never knows what the internal resistance of the battery is at any one point in time. (It is a variable that is hard to predict and varies battery to battery.) If the sensors on a device were able to sense voltage rapidly and the load on the battery remained constant, it would be a cool thing to do. On a variable system such as a robot in competition I don't think it would give as good a response as sensors telling the controller how fast/far motors were responding to stimuli.