Parallel battery configuration for coin cell operated wireless sensor networks

Coin cell batteries have been used in low current application in the past. Due to their low cost and small size, they are an attractive option for use in wireless sensor networks. The rated capacity of a coin cell batter is not achievable. In fact, the achievable life time could be significantly shorter mainly due to characteristics of the draw currents in wireless applications. Measurements have revealed the dependence of coin cell battery capacity on characteristics of the current draw. Here we model lithium CR2032 coin cell battery capacity. It is shown that significant battery life time overestimation could result, if the capacity dependencies are ignored. Parallel coin cell battery configuration is proposed as a simple alternative to single battery case. It is demonstrated that parallel coin cell battery configuration results in longer battery life compared to the single battery case. The battery life improvement factor is shown to be a function of both the current draw and the functional end point voltage. The number of batteries in the parallel configurations influences the results and performance saturation occurs when the number of parallel batteries exceeds three. Based on our estimates, battery improvement factors of up to 600% are obtained.