A Cost-Benefit Analysis of Batteries for Internet-of-Things Applications

The proliferation of wireless IoT devices has caused the energy cost to become an additional figure of merit in designing low-cost and ultra-low-power sensors. This article presents a methodology for a cost-benefit analysis of the battery subsystem for IoT devices. In particular, it analyzes the costs/service time tradeoff of two primary (i.e., non-rechargeable) batteries of different chemistries: the Energizer E91 alkaline cell (zinc-manganese dioxide, Zn/MnO
2
) and the Energizer L91 lithium cell (lithium/iron disulfide, Li/FeS
2
). Although the latter shows a high and very stable performance in terms of total capacity, at different constant and pulse discharge currents, the former shows a significant capacity recovery during the rest times between consecutive pulses. Consequently, the total service time of the E91 differs for different continuous and pulse currents. Results show that the overall cost of a specific choice of a battery needs to be assessed by considering its service time for a given application domain.