Miniaturized g- and spin-activated Pb/HBF4/PbO2 reserve batteries as power sources for electronic fuzes

This paper discusses miniaturized Pb/HBF4/PbO2 reserve batteries (MRB) for military applications as in-flight power sources for small-caliber electronic fuzes, where the setback acceleration and high-spin force in firing environments are used to activate the MRB. The MRB is composed of a series configured 23 bipolar electrodes, an isolated glass ampoule filled with an electrolyte and an internal cutter for breaking the glass ampoule. The MRB is designed to furnish high-voltage electrical energy with a fast activation time in gunfire environments and must have a 20-year shelf life. The electrolyte volume is determined from the simulation results of a CFD program (FLUENT) for reduction in design time and cost. Two kinds of MRBs have been designed and fabricated: MRB-S with one narrow electrolyte-filling microchannel and MRB-D with two. In the experimental study, spin tests under 10,000 × gʹs and~ 20,000 rpm conditions and a fire test under 43,000 × gʹs and 57,000 rpm conditions have been made. The fabricated MRB with a diameter of 16 mm and a height of 13 mm has achieved a maximum voltage of 34.6 ± 0.4 V, an activation time of 8.6 ± 0.6 ms and a maximum capacity of 37.4 ± 0.4 W s at an optimized electrolyte volume of 180 mm3. The test results have verified that the activation time of the MRB at a low temperature of −32 °C can be improved by decreasing the flow resistance of the electrolyte in spite of the decreased ion mobility.