NOVELTY - The method involves comparing usable time on a battery (190) with necessary time for arrival at a selected destination during navigation mode. Power saving mode is activated according to predetermined criteria when the usable time on the battery is less than the necessary time for arrival. A determination is made to check whether residual battery power level is less than a predefined threshold value if a user-defined power saving mode is turned-on. Total battery power of the battery is measured during navigation mode. Battery time is calculated for a set of power consumption levels.    USE - Method for reducing power consumption of a secondary rechargeable battery of a mobile device in a vehicle. Uses include but are not limited to lithium ion battery, nickel battery, cadmium battery, nickel-cadmium battery and chemical cell battery, of mobile communication terminal such as cell phone, personal digital assistant (PDA), tablet personal computer (PC) and portable multimedia player (PMP).    ADVANTAGE - The method enables reducing battery power consumption to conserve battery life when the mobile device executes navigation application. The method allows a mobile user to stop the navigation application before arriving at destination to save the battery power or the navigation application can be unexpectedly stopped before an arrival at the destination. The method enables using a global positioning system (GPS) for receiving time setting function to allow a reduction in power consumption of the battery, thus increasing a battery usable time. The method allows a control unit to increase a screen update cycle of the navigation application depending on decrease in speed of a vehicle, thus preventing the screen from being continuously updated.    DETAILED DESCRIPTION - An INDEPENDENT CLAIM is also included for an apparatus for reducing power consumption of a battery of a mobile device.    DESCRIPTION OF DRAWING(S) - The drawing shows a block diagram of a mobile device.    Mobile device (100)    Touchscreen (140)    Illuminance sensor (160)    Location information receiver (180)    Battery (190)