Abstract: Disclosed are devices configured to execute multiple functions and methods for calculating a remaining power source life value. A method can include providing information related to the remaining power source life value correlated to operation of at least one of the multiple functions. Downloaded current drain information related to current drain during operation of at least one of multiple functions may be received by the device and/or may be internally detected. A current drain profile stored in memory may be updated based on current drain information. A remaining power source life value and/or a time-to-charge value can then be calculated, based on the updated current drain profile.