Abstract: A battery pack may include a plurality of cells, a cell connector assembly, and a common output. The cell connector assembly may be disposed to contact at least selected ones of the plurality of cells to facilitate parallel connection of contacted cells. The common output may be electrically coupled to the cell connector assembly to receive a combined output from the plurality of cells. The cell connector assembly may include a plurality of metallic arms arranged in a hierarchical structure including at least two levels each having at least one arm, such that the cell connector assembly defines a plurality of current paths from each of the contacted cells to the combined output. The plurality of current paths are substantially equal to each other in length.

Abstract: A self-powered chainsaw, typically a battery powered chainsaw, including a housing, a power source, an endless cutting chain having a plurality of cutting elements and a motor arranged to drive the chain relative to the housing using power from the power source. The chainsaw also includes a sharpening element which is arranged so as to be driven relative to the cutting elements and the housing using the power source.

Abstract: A battery pack may include a plurality of cells, a cell connector assembly, and a common output. The cell connector assembly may be disposed to contact at least selected ones of the plurality of cells to facilitate parallel connection of contacted cells. The common output may be electrically coupled to the cell connector assembly to receive a combined output from the plurality of cells. The cell connector assembly may include a plurality of metallic arms arranged in a hierarchical structure including at least two levels each having at least one arm, such that the cell connector assembly defines a plurality of current paths from each of the contacted cells to the combined output. The plurality of current paths are substantially equal to each other in length.

Abstract: A cell housing, such as for a backpack battery pack, includes a first wall, a second wall, and a cell retention structure there-between, wherein the cell retention structure is configured to retain battery cells arranged in a matrix of rows and columns such that the longitudinal axis of each battery cell is substantially parallel to the longitudinal axes of the other battery cells. A plurality of connectors are located on the exterior of the cell housing and are electrically connected to the battery cells through openings in the first and second walls of the cell housing. The connectors electrically connect the cells in each row in parallel and the cells in each column in series. The connectors may comprise unitary connectors that electrically connect the positive terminals of at least two cells of one row of cells to each other and also to the negative terminals of at least two cells of another row of cells.

Abstract: A self-powered chainsaw, typically a battery powered chainsaw, comprising a housing (1; 21), a power source (5; 25), a endless cutting chain (4; 24) having a plurality of cutting elements and a motor (6) arranged to drive the chain (4; 24) relative to the housing (1; 21) using power from the power source (5; 25), in which the chainsaw further comprises a sharpening element (12; 32) which is arranged so as to be driven relative to the cutting elements and the housing (1; 21) using the power source (5; 25).

Abstract: A typically battery-operated power tool, such as a chainsaw or hedge trimmer, comprising a working element (4), a motor (6) arranged to drive the working element (4) and a controller (9) arranged to control the speed at which the motor drives the working element (4), in which there is provided a sensor (12) for at least one factor indicative of the efficiency with which the power tool is being operated, the controller (9) being arranged to vary the speed at which the motor (6) drives the working element (4) should the factor indicate that the power tool is being operated in a sub-optimal manner. Typically, the factor is the pressure which the user is applying the power tool, and the sensor (12) is a sensor for the current flowing through the motor (6).

Abstract: A description is given of a rain indicator (1), which has a light source in the form of a light emitting diode (36) and a light detector in the form of a photodiode (37). There is a light guide (20) made from a material transparent to the light of the light source and e.g. glass, which has at least one surface portion (45, 46) exposed to the precipitation and which is so positioned relative to the light source that the light source light is totally reflectable towards the light detector on the surface portion. When the surface portion is dry light passes by total reflection to the light detector. In the case of precipitation a gap (43, 44) adjacent to the surface portion fills with liquid and the light intensity is substantially coupled out of the light guide (20) and no light passes to the light detector. Total reflection again occurs when the gap dries out.