Abstract: A rechargeable battery pack for a power tool can have a data terminal that provides a signal that is indicative of whether the voltage is below a threshold and can serve as both a pre-charge signal for a charger and as a stop-discharge signal for a power tool. A charger can include a power supply circuit and a voltage detection circuit. A charger control module can receive a signal indicative of the voltage of the battery pack and determine a pre-charge time based on the voltage and can monitor a change in the voltage of the battery pack during the pre-charge operation and stop the pre-charge operation based on the change in voltage and the time period.

Abstract: A rechargeable battery pack comprises a battery having a high voltage side and a low voltage side, a positive terminal accessible external of the battery pack and connected to the high voltage side of the battery, a negative terminal accessible external of the battery pack and connected to the low voltage side of the battery, a control terminal accessible external of the battery pack, a switching element electrically connected between the control terminal and the high voltage side of the battery, and a control module operable to control the switching element so that the control terminal is selectively coupled to the high voltage side of the battery.

Abstract: A method for monitoring the voltage of each of a plurality of cells of a battery pack is provided. The method may include monitoring a voltage potential for each of a plurality of cells in a battery pack utilizing a single channel of battery control unit within the battery pack. If, during discharge of the battery, e.g., the battery is being used to power a hand tool, the voltage potential of any cell is determined by the battery control unit to be below a predetermined minimum voltage, the battery control unit discontinues a current flow from battery pack to the tool. Additionally, during charging of the battery pack, if a voltage differential between any one of the cells and any other one of the cells is determined to be above a predetermined maximum differential, the battery control unit reduces the voltage potential stored in the cell having the higher voltage potential.

Abstract: A control module is included in a battery charger that is adapted to charge a plurality of battery packs of different types or a power tool that is adapted to be powered by at least one of the battery packs. The control module includes a remote sensing module that communicates remotely with one of the battery packs. The control module also includes a battery pack connection module that determines that the one of the battery packs is in electrical communication with at least one of the battery charger and the power tool. The control module also includes a battery pack identification (ID) module that determines a first type of the battery pack based on remote sensing module signals. The control module also includes a charge control module that determines at least one of a charge setting and a discharge setting for the battery pack based on the first type.

Abstract: A power tool system component has a microprocessor, a one wire communication terminal connecting the microprocessor to an external device, and a flash memory storing: (a) an application program governing operation of an application mode during which the power tool system component is operated; and (b) a boot loader program governing operation of a boot loader mode during which at least part of the application program can be updated. The microprocessor accesses the flash memory and implements the boot loader program and the application program by setting up and observing a temporal window during which one or more predetermined conditions must be met for the boot loader mode to be entered. The predetermined conditions include successful completion of a calibration process that includes sending a calibration byte to the external device according to a format predetermined to allow the external device to adjust its baud rate for sending and receiving information.

Abstract: A method and system for authenticating a smart battery having a smart battery and an electronic device. Both the device and the smart battery generate encrypted random strings using key material based by A/D noise bits as a seed value. A pseudo random number is generated from the A/D noise that is transmitted to both the electronic device and the smart battery. The pseudo random number is used by both devices as a key index to select one of a plurality of keys stored in separate key libraries. The keys, or key material, is used to execute an encryption algorithm. The two encryption data streams are then compared to authenticate the smart battery.