Abstract: A stacked battery comprises a first substrate having top and bottom surfaces, and a pair of spaced apart first holes that extend from the top surface to the bottom surface, each first hole having an edge. A first battery cell is on the first substrate, the first battery cell comprising at least a pair of electrode films with an electrolyte therebetween, and a pair of first contact pads, each contact pad contacting an electrode film and an edge of a first hole. A second battery cell is on a second substrate and has a pair of second contact pads that each contact an electrode film and an edge of a first hole. An electrical conductor in each first holes electrically connects a first contact pad to a second contact pad.