A small, 50mm in diameter & 10mm thick, device designed to record multiple parameters remotely without battery replacement. It is based on self-energising event detectors, that consume only around 10 nanowatts. When detectors are triggered, the sensor consumes around 1 microjoule to check and log the event. As a result, decades of lifetime are obtained from a coin cell, if the events occur less than once a minute. It is being developed to monitor cans in long-term storage.