Abstract: A device is disclosed for providing information related to the state of health of rechargeable batteries. The device (10) permanently attaches to the battery and measures key parameters such as battery current, voltage and temperature. Using this information, the device can derive information on the general age and health of the battery. A unique feature is the ability to use any common conductor in series with the battery cells as a current measuring shunt, even if the exact characteristics of the conductor are unknown. Thus the need for a calibrated current shunt or other current measuring sensor is eliminated.

Abstract: A large battery pack of specified voltage and capacity can be assembled from a plurality of identical small cells by dividing the specified capacity by a nominal battery module capacity to determine a desired number of parallel modules to be provided, dividing the nominal battery module capacity by a nominal cell card capacity, to determine the number of cell cards required in each module, connecting the call cards in parallel to a common buswork to form the battery module, and connecting the modules in parallel to obtain the specified battery pack capacity and in series to obtain the specified battery pack voltage Protection circuitry can be implemented at the module level, by disconnecting one or more modules or the entire battery pack if a fault at the module level is identified; at the cell card level, by disconnecting a cell card if a cell within it is determined to be faulty; and/or internally, in each cell.

Abstract: In the particular embodiments described in the specification, a controllable pitch propellor arrangement includes a plurality of propellor blades supported from a central hub which is rotatably mounted on a shaft in which each blade is pivotally supported from the central hub. Two radial pins extending from the outer ends of each of the blades are received in corresponding rims having peripherally disposed permanent magnet arrays. The rims are rotated to drive the propellor by energization of coils in a stator assembly surrounding the rims and the pitch of the blades is changed by changing the phase relationship of the current supplied to the stator coils to change the angular relation of the rims.