Vehicle battery management systems (BMS) and methods are described, in which the output of a vehicle battery is reduced by activating a shutdown mode. A BMS may be configured to start a timer when the vehicle is turned off, e.g. based on when the main power between the vehicle and the battery is interrupted or based on a signal from the vehicle control system. The BMS may further be configured to store BMS data (e.g. variable data related to operation and/or status of the battery) to an electronic storage device, and to switch the battery to a shutdown mode, when the timer reaches a predetermined value. The BMS may be further configured to load the BMS data from the electronic storage device and/or to deactivate the shutdown mode when the vehicle is turned back on.