A method for powering electrically powered surgical instruments includes removably inserting a cordless battery assembly into a handle thereof, the instrument handles having a battery chamber and different types. The battery assembly comprises an energy cell powering a signal generation assembly of the instruments. A battery/handle interface has connectors mating with connectors within the chamber. A voltage-control circuit is operable to communicate with and power the signal generation assembly, detect which handle type is connected to the battery assembly, and provide different outputs in response to a detection of the handle types. As the battery assembly is inserted, connectors of the battery/handle interface are coupled with connectors within the battery chamber to communicatively couple the voltage-control circuit to the signal generation assembly and provide power thereto. The connected handle is detected and dependent upon the detected handle type a different one of the outputs are provided.