A power tool system, comprising: a first battery pack comprising a first plurality of battery cells and configured to provide only a first operating voltage; a second battery pack comprising a second plurality of battery cells and configured to provide the first operating voltage and a second operating voltage that is different from the first operating voltage; a first power tool comprising a first set of power terminals and configured (a) to operate at the first operating voltage, (b) to mechanically and electrically couple with the first battery pack such that the first battery pack provides the first operating voltage to the first power tool, and (c) to mechanically and electrically couple with the second battery pack such that the second battery pack provides the first operating voltage to the first power tool; and a second power tool comprising a second set of power terminals and configured (a) to operate at the second operating voltage, and (b) to mechanically and electrically couple with the second battery pack such that the second battery pack provides the second operating voltage to the second power tool, wherein the second plurality of cells comprise a first subset of cells connected in series and a second subset of cells connected in series, wherein, when the second battery pack is coupled to the first power tool, the first subset and the second subset are connected in parallel to provide the first operating voltage to the first power tool, and wherein, when the second battery pack is coupled to the second power tool, the first subset and the second subset are connected in series to provide the second operating voltage to the second power tool. a first battery pack comprising a first plurality of battery cells and configured to provide only a first operating voltage; a second battery pack comprising a second plurality of battery cells and configured to provide the first operating voltage and a second operating voltage that is different from the first operating voltage; a first power tool comprising a first set of power terminals and configured (a) to operate at the first operating voltage, (b) to mechanically and electrically couple with the first battery pack such that the first battery pack provides the first operating voltage to the first power tool, and (c) to mechanically and electrically couple with the second battery pack such that the second battery pack provides the first operating voltage to the first power tool; and a second power tool comprising a second set of power terminals and configured (a) to operate at the second operating voltage, and (b) to mechanically and electrically couple with the second battery pack such that the second battery pack provides the second operating voltage to the second power tool, wherein the second plurality of cells comprise a first subset of cells connected in series and a second subset of cells connected in series, wherein, when the second battery pack is coupled to the first power tool, the first subset and the second subset are connected in parallel to provide the first operating voltage to the first power tool, and wherein, when the second battery pack is coupled to the second power tool, the first subset and the second subset are connected in series to provide the second operating voltage to the second power tool. <EOS>