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 medium-voltage-rated removable battery pack having a maximum rated voltage in the range of 40 to 80 volts, and a brushless direct current (BLDC) motor. The motor includes a rotor and a stator having at least three stator windings corresponding to at least three phases of the motor, the rotor being moveable by the stator when the stator windings are appropriately energized within the corresponding phases. A multi-phase inverter bridge circuit is disposed between the power supply interface and the motor, and a controller is configured to output drive signals to the inverter bridge circuit to control flow of current from the battery pack to the motor such that the motor produces a maximum power output of at least approximately 1750 watts at a torque of approximately 1.5 to 2 Newton-meters.

A power tool is provided including a power supply interface receiving a medium-voltage-rated removable battery pack having a maximum rated voltage in the range of 40 to 80 volts, and a brushless direct current (BLDC) motor. The motor includes a rotor and a stator having at least three stator windings corresponding to at least three phases of the motor, the rotor being moveable by the stator when the stator windings are appropriately energized within the corresponding phases. A multi-phase inverter bridge circuit is disposed between the power supply interface and the motor, and a controller is configured to output drive signals to the inverter bridge circuit to control flow of current from the battery pack to the motor such that the motor produces a maximum power output of at least approximately 1750 watts at a torque of approximately 1.5 to 2 Newton-meters.

A battery balancing system includes an energy balancing circuit. Multiple battery cells are coupled to the energy balancing circuit. A health assessment circuit is coupled to the multiple battery cells and configured to sense a state of health and a charge of each of the multiple battery cells. The balancing circuit switches energy between the multiple battery cells as a function of the sensed state of health and state of charge of each of the multiple battery cells to balance charge there between.

A battery balancing system includes an energy balancing circuit. Multiple battery cells are coupled to the energy balancing circuit. A health assessment circuit is coupled to the multiple battery cells and configured to sense a state of health and a charge of each of the multiple battery cells. The balancing circuit switches energy between the multiple battery cells as a function of the sensed state of health and state of charge of each of the multiple battery cells to balance charge there between.

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.

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.

In a loaded condition, the controller increases at least one of the conduction band or the advance angle from a baseline value up to a maximum value within a first torque range below a torque threshold to as to maintain the output speed of the motor at a linear speed-torque profile. After the at least one of the conduction band or the advance angle reaches the maximum value, the controller maintains the at least one of the conduction band or the advance angle at the maximum value within a second torque range greater than or equal to the torque threshold so as to maintain the output speed of the motor at a naturally-curved speed-torque profile.

In a loaded condition, the controller increases at least one of the conduction band or the advance angle from a baseline value up to a maximum value within a first torque range below a torque threshold to as to maintain the output speed of the motor at a linear speed-torque profile. After the at least one of the conduction band or the advance angle reaches the maximum value, the controller maintains the at least one of the conduction band or the advance angle at the maximum value within a second torque range greater than or equal to the torque threshold so as to maintain the output speed of the motor at a naturally-curved speed-torque profile.