Unintentional thermal battery activation due to missile system power application to battery outputs; cause and corrective actions

A thermal battery was designed and developed for use on the Phoenix Missile. This batter met a rigorous matrix of nondestructive and destructive tests required for qualification and was undergoing system integration tests when an unintentional activation of the 100 V section of the battery occurred. The application of a high-voltage ground power supply in parallel with the battery output terminals during a mission simulation test resulted in the unintentional activation of the thermal battery. Several activation mechanism investigations were conducted to study breakdown/ignition phenomena and provide a data-supported mechanism sequence. These included the evaluation of a capacitive mechanism as well as determination of temperature and time effects on electrolyte microconduction. Experimental results are presented and analyzed. Battery design changes in the form of internal battery electrochemical considerations and external electronic approaches are presented and discussed