Abstract: An electrical combination including a driver drill capable of producing an average current draw of approximately 20-amps, a circular saw capable of producing an average current draw of approximately 20-amps, and a power tool battery pack operable to supply power to the driver drill and to the circular saw, the battery pack including a plurality of battery cells, the plurality of battery cells each having a lithium-based chemistry.

Abstract: A combination including a battery pack and a battery charger operable to supply a charging current to the battery pack. The battery pack includes a first battery terminal, a second battery terminal, and a battery cell having a present state of charge. The battery cell is coupled to at least one of the first battery terminal and the second battery terminal. The battery pack also includes a battery microcontroller coupled to at least one of the first battery terminal and the second battery terminal. The microcontroller is operable to measure the present state of charge of the battery cell to produce battery cell present state of charge measurements. The battery charger includes a first charger terminal configured to couple to at least one of the first battery terminal and the second battery terminal and a second charger terminal configured to couple to at least one of the first battery terminal and the second battery terminal.