Extending lifetime of battery operated wireless sensor node with DC-DC switching converter

In this paper we study lifetime extension of a wireless sensor node operated from primary battery through a DC-DC switching converter. The node was developed in course of the environmental monitoring project MasliNET. A step-up switching converter is needed to drain the battery when its voltage drops below the operating voltage of the node. In order to minimize the losses caused by the DC-DC converter it is important to shut it down whenever possible and keep the difference between its input and output voltage low. We have developed a controllable power-supply unit and a dynamic control algorithm that manages the use and the output voltage of the DC-DC converter based on the current node's task requirements and the battery state. We have experimentally verified the solution by comparing it to the node permanently operated from a fixed output voltage DC-DC converter. It has been shown that the proposed power-supply design and the control algorithm prolong battery lifetime as much as 30 %.