ornitz@kodak.UUCP (03/05/87)
In article <1630@kitty.UUCP> larry@kitty.UUCP (Larry Lippman) writes: > I don't know anything about the above Russian device, but I can >comment about a "thermal battery" which was developed during World War II >for use as a power source for electronic proximity fuses used in artillery >shells and rockets. > This thermal battery consisted of two thermopiles (i.e., an array of >thermocouple junctions in series-parallel): one for low-voltage, high-current >for filament power, and the other for high-voltage, low-current for plate B+ >power. The thermopiles were powered by the hot exhaust gases and burning >propellant of mortar shells, anti-submarine rockets, etc. > The thermal battery is an interesting device since it must be capable >of several years shelf-life, but yet be ready for instant use with a high >degree of reliability. The actual operational life of the battery is usually >measured in seconds. A more common form of the military thermally actuated battery is a conventional primary cell with a solid salt as an electrolyte. A pyrotechnic charge is used to melt the salt immediately prior to use. The primary use of this battery is in applications as described above: many years of shelf life with almost no degree of degradation, high reliability, and high power density. With a solid salt electrolyte, ion mobility and kinetics are nil. Once the salt is molten, ion mobility is good and the reaction kinetics are quite high. Pyrotechnic igniters have shown a high degree of operating reliability. Power density is good at the high temperatures involved. Operating life of these batteries is usually less than one hour and often several minutes. Barry