One embodiment of the present subject matter includes an implantable medical device which includes a first power source comprising a first plurality of substantially planar electrodes, the first power source including at least a first power source face, an electronics module including a first substantially planar electronics face, and a second electronics face opposed to the first substantially planar electronics face, with the first substantially planar electronics face adjacent to, and substantially coextensive with, the first power source face and a second power source comprising a second plurality of substantially planar electrodes, the second power source positioned adjacent to and adapted to interface with the second electronics face.
