An example includes apparatus including a non-thin-film battery, that can include an implantable housing, electronics disposed in the implantable housing, and a battery disposed in the implantable housing, the battery comprising: a plurality of cells electrically connected to one another, with at least one cell including a stack including at least one substantially planar anode having a thickness greater than 1 micrometer and at least one substantially planar cathode having a thickness greater than 1 micrometer, and a cell housing enclosing the stack of substantially planar anodes and cathodes and displacing less than approximately 0.024 cubic centimeters, wherein the plurality of cells are interconnected in at least one of series and parallel, and terminals interconnecting the battery and the electronics.