Abstract: A controller or processing system for a vehicle, such as a passenger service vehicle, the vehicle having at least one energy storage system, at least one alternator or other charging device coupled to and/or operable or driven by an engine or motor, wherein the alternator or other charging device is switchable between an operational state and a non-operational state by the controller or processing system responsive to one or more parameters of the vehicle. The invention also includes an associated vehicle and method. The parameters of the vehicle optionally include one or more or each of: acceleration of the vehicle, accelerator pedal position, vehicle speed, rotation speed of the engine, the gear currently selected and/or the current being drawn from, or load on, the at least one energy storage system and/or current being drawn by one or more or all electrical components of the vehicle and/or engine coolant temperature.