The described principles provide a method and system for assisting a user of an electric vehicle in maintaining a charge state of the chargeable onboard energy storage system so as to be able to forgo the use of an auxiliary power unit to great extent. The method, also implemented by the system, comprises identifying charging locations for the vehicle, and prompting the user to charge the vehicle when the vehicle is at a charging location and a charge is need to avoid the use of the auxiliary power unit for a learned or planned journey. The charge reminder my be visible and/or audible within the vehicle and may optionally be remote from the vehicle.