A method and apparatus for determining estimated remaining longevity for an implantable stimulator. A programmer processor is employed to acquire from the implantable stimulator a signal comprising data associated with the power source in the implantable stimulator and a date in which the stimulator was implanted. The programmer processor and the data are used to determine whether a pre-recommended replacement time threshold (pre-RRT) has been attained for replacing the implantable stimulator. The programmer processor is used to select an equation in which to calculate a recommended replacement time (RRT), the equation is selected in response to determining a time period that extends from the date in which the stimulator was implanted until a date in which the pre-RRT is attained.
