Abstract: One use of datalogger's is for gathering physiological conditional data about a person. A person can carry a datalogger and any associated sensors whilst they are in motion. The data recorded by the datalogger can then be uploaded to a third party system for analysis. Datalogger's that record physiological information have a variety of uses. For example, they can be used for medical purposes to monitor a patient's response to a course of treatment, or to monitor background factors about a person's lifestyle that may allow a doctor to advise on healthy living, and for sports purposes, to monitor an athlete's performance. Energy consumption is a significant issue in the design of datalogger's. It is desirable for a datalogger to be small and light, with a self-contained energy source such as a battery, but also to operate for as long as possible. This document describes means to prolong the life of the battery attached to both sensory devices and datalogger's alike.