It is dependents mostly on how much driving is done. The motors by far consume the most power in a robot. Battery capacity is rated in Amp/hours, which is the amount of Amps it can deliver for one hour before it is empty. So if a robot has two motors that draw an average of 20A each (40A) total, then the robot will be able to move for up to 1 hour on a 40A/h battery. When the motors are idle, the controller's output stage draws no power. At all times that it is turned on, the controller will consume approximately 150mA for its internal electronic circuitry.