Abstract: Displaying remaining longevity of energy source of implantable medical device having a longevity characterized by a depth of discharge representative of a first stage of discharge, e.g., beginning of service, a second stage of discharge, e.g., recommended replacement time, and a third stage of discharge, e.g., end of service. A display is configured to display in graphical form using a scale length representative of a time between the first stage of discharge and the third stage of discharge. A first portion of the display between the second stage of discharge and the third stage of discharge is indicated in a first color, e.g., red. A second portion of the display between the remaining longevity and the second stage of discharge is indicated in a second color, e.g., green. A third portion of the display between the first stage of discharge and the remaining longevity is indicated in a third color, e.g., white.