[Kevin Sevcik]

For the record, "Coasting" isn't exactly electrically identical to disconnecting the leads of the motor, though it's functionally equivalent under most operating conditions. The FETs that make up the H-bridge have body diodes that make the H-bridge a rectifier when the FETs are unpowered. A rambling explanation follows.

If the robot is turned off, the voltage generated by a turning motor feeds back through these diodes to the Jag's V+/- terminals and can actually power up your robot. Which means there's current flowing through the motor, which means resistance to turning.

If the robot's turned on, there's +12V across the Jag's V+/- terminals. Which means the voltage generated by the motor would have to exceed (12+1.4)V before any current would flow and cause resistance. That's highly unlikely, but theoretically possible. For instance, if you spin a shooter up to full speed then put it in coast, the motor's generating near to 12V. If you then get in a shoving match that drops your battery voltage to 9V, the voltage generated by the shooter motor will be greater than the input voltage on the Jag. The difference in voltage means current will start flowing, slowing the motor more rapidly, and actually powering the rest of your robot slightly.