R and D for Hybrid Battery and Cell Studies

Three areas of work are described. These are the Primary Battery Investigation, the Secondary Battery Investigation, and the System Design and Charge Control Development. The primary battery investigation covered zinc-air, Li-organic, Zn-HgO, and Mg-MnO2 cells with cell performance being characterized over a temperature range of -40 to 140F and a load current range of C/250 to C/5. Highest energy density was obtained from the zinc-air and Li-organic cells with the zinc-air cells showing superior energy density at temperatures above 0F and the Li-organic cells giving better performance at temperatures below 0F. Energy density, voltage and capacity data are presented for the primary systems over the temperature and load range previously indicated. A high-rate low temperature sealed nickel-cadmium cell, of a sub-C size, was developed and is described. Secondary performance data indicates that hybrid operation, at discharge and charge rates of 6C and 1C, respectively and cell temperatures as low as 10F, will be possible without parasitic heaters. Reliable operation below 10F will require the use of parasitic heaters. Various methods of charge state sensing and charge control were investigated and are described.