Watts Better Than mAh for IoT Devices?

Traditional methods of estimating battery runtime for IoT devices involve measuring current over a typical period of device operation, computing the area under the current waveform to find the charge consumed, and dividing that area into the battery capacity (specified in mAh) to find the number of typical operation cycles a device might perform from a full charge. While this is very useful, it does have some limitations that come from incorrect assumptions about the way IoT devices behave over time. The dynamic behavior of IoT devices has challenging consequences for battery runtime estimates, and depending on the nature of the application, there could be serious consequences for the end user if an IoT device battery failed prematurely. This paper describes the use of event-based power analysis to characterize an IoT device as it operates at various supply voltages, and it demonstrates a very simple computation that improves battery life estimates. By thus improving the accuracy of their battery runtime estimates, engineers can quickly make hardware, firmware, and system configuration decisions to optimize battery runtime and meet the needs of customers more quickly.