A battery pack and charger system includes a first battery pack having a first set of battery cells and configured to provide only a first operating voltage and a second battery pack having a second set of battery cells and configured to provide the first operating voltage and a second operating voltage that is different from the first operating voltage and a battery pack charger configured to be able to charge the first battery pack and the second battery pack.

A battery pack and charger system includes a first battery pack having a first set of battery cells and configured to provide only a first operating voltage and a second battery pack having a second set of battery cells and configured to provide the first operating voltage and a second operating voltage that is different from the first operating voltage and a battery pack charger configured to be able to charge the first battery pack and the second battery pack.

A battery pack and charger system includes a first battery pack having a first set of battery cells and configured to provide only a first operating voltage and a second battery pack having a second set of battery cells and configured to provide the first operating voltage and a second operating voltage that is different from the first operating voltage and a battery pack charger configured to be able to charge the first battery pack and the second battery pack.

A charging circuit for an electrical energy storage system having electrical energy storage units. The charging circuit includes a first input and a second input for electrically connecting to an energy source, a first output and a second output, and first pole connections and second pole connections. The pole connections are connected in an electrically conductive manner to corresponding pole connections of the electrical energy storage units. In addition, the charging circuit includes first switches, second switches, and third switches.

According to one aspect of the present disclosure, an energy storage system includes one or more power sources, one or more energy storage components, and one or more solid state circuit breakers disposed between the one or more power sources and the one or more energy storage components such that electrical power is exchanged between the one or more power sources to the one or more energy storage components through the one or more solid state circuit breakers. The energy storage system also includes a controller configured to operate the one or more solid state circuit breakers to control current exchanged with the one or more energy storage components and protect the one or more energy storage components from the one or more power sources during a fault condition.

An adaptive vehicle power system provides an interface between a vehicle twelve-volt electrical system and a twelve, twenty-four, thirty-six or higher voltage battery bank for a vehicle load, such as a motor or other device, to allow operation of the load using the battery bank. In one embodiment, the adaptive vehicle power system automatically senses when the vehicle electrical system is operating properly and automatically switches into a charging mode to charge the battery bank from the vehicle electrical system.

An electrochemical cell management system comprising an electrochemical cell and at least one controller configured to control the cell such that, for at least a portion of a charge cycle, the cell is charged at a charging rate or current that is lower than a discharging rate or current of at least a portion of a previous discharge cycle. An electrochemical cell management method. An electrochemical cell management system comprising an electrochemical cell and at least one controller configured to induce a discharge of the cell before and/or after a charging step of the cell. An electrochemical cell management method. A electrochemical cell management system comprising an electrochemical cell and at least one controller configured to: monitor at least one characteristic of the cell and, based on the at least one characteristic of the cell, induce a discharge and/or control a charging rate or current of the cell.

A power tool is provided including a power supply interface receiving a removable battery pack, a brushless direct current (BLDC) motor including a rotor and a stator, and a multi-phase inverter bridge circuit. A controller is provided to output drive signals to the inverter bridge circuit to control flow of current from to the motor, where each drive signal is activated within each corresponding phase of the motor within a conduction band. The controller is configured to control a length of the conduction band at a variable value within a first torque range below a torque threshold and at a substantially constant value within a second torque range above the torque threshold. The torque threshold is greater than approximately 1 Newton-meters and the motor produces a maximum power output of at least approximately 1250 watts at the torque of approximately 1 Newton-meters.

A power tool is provided including a power supply interface receiving a removable battery pack, a brushless direct current (BLDC) motor including a rotor and a stator, and a multi-phase inverter bridge circuit. A controller is provided to output drive signals to the inverter bridge circuit to control flow of current from to the motor, where each drive signal is activated within each corresponding phase of the motor within a conduction band. The controller is configured to control a length of the conduction band at a variable value within a first torque range below a torque threshold and at a substantially constant value within a second torque range above the torque threshold. The torque threshold is greater than approximately 1 Newton-meters and the motor produces a maximum power output of at least approximately 1250 watts at the torque of approximately 1 Newton-meters.

A secondary battery system of connecting secondary batteries includes first output-unit switches, second output-unit switches, series-connection switches, a positive-side discharging output unit connected to second terminals of the first output-unit switches, a negative-side discharging output unit connected to second terminals of the second output-unit switches, a positive-side charging input unit connected between a positive terminal of one of the secondary batteries at one end of the secondary batteries and a first terminal of one of the first output-unit switches associated with the one of the secondary batteries at the one end of the secondary batteries, a negative-side charging input unit connected between a negative terminal of one of the secondary batteries at the other end of the secondary batteries and a first terminal of one of the second output-unit switches associated with the one of the secondary batteries at the other end of the secondary batteries, and a control unit.