Spin Dependent Tunneling Sensors With Improved Stability and Low Hysteresis

This project proposes the development of a robust, low cost, high density, hybrid power system. The most important features of the proposed approach are: 1) The implementation of the best commercially available power production components with emphasis onsimplicity, robustness, and low cost. The baseload and intermediate power (15 W to 50 W) will be provided by a proton exchange membrane fuel cell (PEMFC) commercially available from H-power and the peak power will be provided by a proven, high performanceNickel-Metal-Hydride battery available from Energizer. In phase I bottled hydrogen will be used to fuel a brass board demonstrator and in phase II one of two candidate hydrogen storage technologies will be integrated. 2) A robust and simple overallconfiguration which places the fuel cell and battery directly in parallel. Careful selection of cell counts in both the fuel cell and battery will lead to a system that does not draw from the battery until the power level reaches ~ 50 W but still providesenough overvoltage at baseload power (15 W) to trickle charge the battery. This simple approach is made practical by the implementation of a battery management strategy based on slight variations in fuel cell air stoichiometry (i.e. slight changes in airsupply). 3) An efficient, robust, and low cost control strategy that employs the SmartGuardTM battery management technology developed at AeroVironment. The SmartGuard is a commercially available battery management system that can be slightly adapted toprovide the control requirements of this system. SmartGuardTM will cost only $50 per unit.