Reliability of lithium batteries in search and rescue beacons

Search and rescue beacons, such as ELTs, EPIRBs and PLBs, use a variety of lithium batteries. Similar electrical demand on the battery and the requirement for low temperature performance in particular are common amongst all SAR beacon batteries. They must remain inactive for many years then operate the beacon in a life or death situation this is the essence of the reliability issue. How is reliability to be assessed? The condition of lithium batteries retrieved after five years of field use in EPIRBs was ascertained. Cell failures, inadequate battery designs, poor assembly techniques and quality control lapses were all in evidence. Studies of cells commonly used in beacons have called into question their ability to power the beacons for typical service lifetimes. Deterioration in the performance of some of the lithium products contradicted the oft-quoted ‘10-year shelf-life’ for lithium batteries.