A thin film battery comprises a substrate having a surface, and a plurality of battery cells on the substrate surface. Each battery cell comprises an electrolyte having opposing surfaces, and a plurality of conductors in electrical contact with at least one of the opposing surfaces of the electrolyte, the plurality of conductors including a first conductor in electrical contact with a surface of the electrolyte and a second conductor in electrical contact with the opposing surface of the electrolyte. At least one electrical connector strip connects a conductor of a first battery cell to a conductor of a second battery cell to electrically couple the first and second battery cells to one another.