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 machine tool device for a portable machine tool in one embodiments includes at least one coupling unit which couples a machining tool and at least one drive unit configured to drive the coupling unit. The machine tool device includes a recuperation unit which provides, in at least one deactivated state of the drive unit, electrical energy which supplies at least one functional unit from a kinetic energy of at least the coupling 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.

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 multi-voltage battery pack including a converting system for converting the battery pack between a low voltage configuration and a high voltage configuration. The converting system includes a converter element moves between a first position and a second position to configure the battery pack between the low voltage configuration and the high voltage configuration. The converter element includes a set of contacts that mates with a set of contact pads to establish the voltage configuration.

A multi-voltage battery pack including a converting system for converting the battery pack between a low voltage configuration and a high voltage configuration. The converting system includes a converter element moves between a first position and a second position to configure the battery pack between the low voltage configuration and the high voltage configuration. The converter element includes a set of contacts that mates with a set of contact pads to establish the voltage configuration.

A speed control system of a universal motor is electrically connected with a universal motor and includes a speed detecting unit and a controller. The controller is provided with a slow start unit, a speed control unit and a stopping-protecting unit. The slow start unit enables the rotating speed of the universal motor to increase smoothly, and the speed control unit controls and compensates the rotating speed of the universal motor in a way of closed loop, able to achieve effect of stepless speed adjustment and, when used at low speed, having cutting ability similar to that when operated at high speed. The stopping-protecting unit is able to automatically cut off power and carry out protection when machine table is stopped.

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.