A battery assembly is used in battery-powered surgical instruments with handles having a battery chamber and different handle types. The battery assembly includes a housing having an exterior shape formed to removably connect with the battery chamber of the handles and a voltage-control circuit. The housing has at least one energy storage cell operable to power a signal generation assembly of the surgical instruments and a battery/handle interface having a plurality of connectors shaped to mate with a plurality of corresponding connectors within the battery chamber of the handles. The voltage-control circuit is operable to communicatively couple with and provide power to the signal generation assembly, detect which one of the handle types is connected to the housing, provide a first output in response to a detection of a first handle type, and provide at least a second output in response to a detection of a second handle type.