IMPEDANCE EFFECTS OF RECHARGEABLE BATTERIES ON DIGITAL-COMMUNICATION DEVICES

Present (and future) wireless communications use (will use) digital el ectronics to bunch and pack more data into the available communication s spectrum. This strategy requires an energy storage device capable of delivering large, pulsed currents which may approach 4A for 15msec on ce every 90msec. Emerging energy storage technologies, such as nickel- metal hydride and Li-ion cells, have enhanced energy densities but gre ater internal impedance when compared to the traditional nickel-cadmiu m cells. Experiments simulating battery discharge in a digital wireles s communications application demonstrate the effects of internal imped ance on the overall ability of the cells to meet digital device requir ements. Results indicate that, currently, nickel-cadmium may be the be st available technology for these digital applications.