Abstract: Some embodiments provide a portable power supply comprising a housing having a plurality of sides defining an internal cavity. The portable power supply further includes a battery cell assembly positioned in the internal cavity. The battery cell assembly includes a frame and a plurality of battery cells arranged in the frame. Each of the battery cells includes a cathode end, an anode end opposite the cathode end, and a body extending between the cathode end and the anode end. A thermistor is disposed on a respective battery cell of the plurality of battery cells. The thermistor is located nearer to the anode end than to the cathode end of the battery cell.

Abstract: An inductive heater assembly for heating a power tool battery pack, the inductive heater assembly comprising a housing, a battery pack interface configured to receive the power tool battery pack, a charging base, a coil portion located within the housing. The coil portion including a first coil winding and a second coil winding configured to generate an electromagnetic field, wherein the first coil winding and the second coil winding to form a Helmholtz coil.

Abstract: Systems described herein include a battery pack including one or more battery cells and a first resistive element connected to a positive electrode of a first battery cell. The systems also include an external device capable of receiving the battery pack. The external device includes a second resistive element, a switch, and a controller. The second resistive element is configured to be in series with the first resistive element upon the battery pack being received within the external device. The switch is positioned in series with the second resistive element and a common potential is coupled to both the battery pack and the external device. The controller is configured to activate the switch, measure a voltage between the first resistive element and the second resistive element in response to the switch being activated, and determine an identification of the battery pack based on the measured voltage.