Abstract: A battery pack for powering a cordless power tool. The battery pack includes at least one battery cell operable to supply a discharge current, a switch operable to control the discharge current and a protection device to protect the switch. The protection device is positioned such that the device absorbs a current traveling in a direction opposite to that of the discharge current supplied from the battery cell.

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.

Abstract: A method for conducting an operation including a power tool battery pack. The battery pack can include a housing, a first cell supported by the housing and having a voltage, and a second cell supported by the housing and having a voltage. The battery pack also can be connectable to a power tool and be operable to supply power to operate the power tool. The method can include discharging one of the first cell and the second cell until the voltage of the one of the first cell and the second cell is substantially equal to the voltage of the other of the first cell and the second cell.

Abstract: A system and method for battery protection. In some aspects, a power tool battery pack operable to supply power to a power tool includes a controller. The controller is operable to sample a battery pack condition in at least a first sampling mode and a second sampling mode to produce a plurality of measurements. The controller is further operable to average the plurality of measurements to produce an averaged measurement, and operable to modify operation of the battery pack when the averaged measurement is outside a specified range.

Abstract: A method and system for battery charging. In some aspects, a battery charger includes a controller and a charging circuit that is operable to charge Lithium-based batteries of varying nominal voltages and/or number of battery cells.

Abstract: A method and system for battery charging. In some aspects, an electrical combination including a battery charger operable to supply a charging current to a battery to charge the battery and a battery including a switch having an interrupt condition, in which the switch is operable to interrupt a discharge current from the battery. The battery is electrically connectable to the battery charger and the supply of the charging current from the battery charger to the battery is enabled when the switch is in the interrupt condition.

Abstract: A method and system for battery charging. In some aspects, a battery charger including at least one terminal to electrically connect to a lithium-based chemistry battery pack and a controller operable to provide a charging current to the battery pack through the at least one terminal. The controller is operable to select a threshold for a charging function according to a nominal voltage of the battery pack.

Abstract: A method for conducting an operation including a power tool battery pack. The battery pack can include a housing, a first cell supported by the housing and having a voltage, and a second cell supported by the housing and having a voltage. The battery pack also can be connectable to a power tool and be operable to supply power to operate the power tool. The method can include discharging one of the first cell and the second cell until the voltage of the one of the first cell and the second cell is substantially equal to the voltage of the other of the first cell and the second cell.

Abstract: A method and system for battery charging. In some aspects, an electrical combination comprises a first battery having a Lithium-based chemistry, the first battery having a first nominal voltage in a nominal voltage range, a second battery having a Lithium-based chemistry, the second battery having a second nominal voltage, the second nominal voltage being different than the first nominal voltage and being outside of the nominal voltage range, and a battery charger operable to charge the first battery and the second battery.

Abstract: A system and method for battery protection. In some aspects, a battery pack including a housing, a cell supported by the housing and power being transferable between the cell and an electrical device, a circuit supported by the housing and operable to control a function of the battery pack, and a heat sink in heat transfer relationship with the circuit and operable to dissipate heat from the circuit.

Abstract: A system and method for battery protection. In some aspects, a method of conducting an operation including a battery pack, includes the acts of monitoring a first battery pack condition at a first monitoring rate, determining when a second battery pack condition reaches a threshold, after the second battery pack condition reaches the threshold, monitoring the first battery pack condition at a second monitoring rate, the second monitoring rate being different than the first monitoring rate.

Abstract: A system and method for battery protection. In some aspects, a method of a method for operating a battery pack. The battery pack having a battery pack condition, and the battery pack condition having a range. The method including the acts of conducting an operation including the battery pack, measuring a first measurement of the battery pack condition, measuring a second measurement of the battery pack condition, averaging the first measurement and the second measurement to provide an average measurement and if the average measurement is within the range, continuing the operation including the battery pack. At least one of the first measurement and the second measurement being outside of the range.

Abstract: A method and system for battery charging. In some aspects, an electrical combination comprises a first battery having a Lithium-based chemistry, the first battery having a first nominal voltage in a nominal voltage range, a second battery having a Lithium-based chemistry, the second battery having a second nominal voltage, the second nominal voltage being different than the first nominal voltage and being outside of the nominal voltage range, and a battery charger operable to charge the first battery and the second battery.

Abstract: A method for conducting an operation including a power tool battery pack. The battery pack can include a housing, a first cell supported by the housing and having a voltage, and a second cell supported by the housing and having a voltage. The battery pack also can be connectable to a power tool and be operable to supply power to operate the power tool. The method can include discharging one of the first cell and the second cell until the voltage of the one of the first cell and the second cell is substantially equal to the voltage of the other of the first cell and the second cell.