A portable lighting device having a plurality of modes of operation and method of operating the portable lighting device are disclosed. One method of operating the portable lighting device is by rotating the portable lighting device along a principal axis of projection of the light source to enter into a new mode of operation. Normal, dim, motion sensitive, variable brightness, blink, right and left hand, lock out, SOS, night light, strobe, compass and signal modes are disclosed, and the modes may be adjusted. A rechargeable battery pack is disclosed that includes a housing, a rechargeable battery, and an accelerometer. A battery cassette is disclosed that provides a negative electrode at each end of the battery cassette, and a central connector that provides a positive electrode at both ends of the battery cassette.