A Recursive Battery Model for Nodes Lifetime Estimation in Wireless Sensor Networks

Since sensor nodes use batteries as their source of energy, energy-based routing becomes an important requirement to extend network lifetime. This routing is done using the nodes remaining energy information. Nonetheless, this information cannot be estimated using built-in primitives in nodes powered by a lithium-ion battery. In this paper, we introduce an efficient battery model that estimates the remaining energy of a node independently of its battery chemistry. Our model is based on an existing battery model that uses the current consumption during a state and its duration to estimate the battery remaining energy. The original model is very accurate, however, it cannot be implemented in a sensor node as it requires complex computations and large lookup tables. Therefore, we present a recursive approximation of this model that requires low memory and simple computation, while maintaining the original model accuracy. Through extensive real battery discharge measurements, we demonstrate the accuracy of our model and in addition, we show that the ideal model widely used to estimate sensor nodes remaining energy is not accurate.