Abstract: An electrical combination including a power tool and a battery pack. The power tool includes power tool terminals. The battery pack is configured to be interfaced with the power tool. The battery pack includes a battery pack housing, at least three terminals, and a plurality of battery cells. The battery pack terminals include a positive terminal, a negative terminal, and a sense terminal. The at least three terminals are configured to be interfaced with the power tool terminals. The plurality of battery cells are arranged within and supported by the battery pack housing. Each of the battery cells has a lithium-based chemistry and a respective state of charge, and power is transferable between the battery cells and the power tool. A circuit is configured to monitor the battery cells, detect a charge imbalance among the battery cells, and prevent the battery pack from operating when the charge imbalance is detected.

Abstract: An electrical combination including a power tool and a battery pack. The power tool includes power tool terminals. The battery pack is configured to be interfaced with the power tool. The battery pack includes a battery pack housing, at least three terminals, and a plurality of battery cells. The battery pack terminals include a positive terminal, a negative terminal, and a sense terminal. The at least three terminals are configured to be interfaced with the power tool terminals. The plurality of battery cells are arranged within and supported by the battery pack housing. Each of the battery cells has a lithium-based chemistry and a respective state of charge, and power is transferable between the battery cells and the power tool. A circuit is configured to monitor the battery cells, detect a charge imbalance among the battery cells, and prevent the battery pack from operating when the charge imbalance is detected.

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: 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: 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: 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: 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 plurality of battery cells having a lithium-based chemistry and a present state of charge. The battery pack also includes a battery microcontroller that is operable to measure the present state of charge of at least one of the battery cells to produce battery cell present state of charge measurements. The battery charger includes a charger microcontroller that is operable to receive the battery cell present state of charge measurements from the battery microcontroller. The charger microcontroller is also operable to supply the charging current to the battery pack in pulses, wherein each pulse includes a first time interval where charging current is being supplied to the battery and a second time interval where charging current is being suspended from the battery.