“This tutorial demonstrates how to make an ultra low power sensor data logger running on 2 AA batteries for more than a year.
Recently I tried to make a data logger using ESP8266, to periodically upload temperature/humidity/moisture measurements to a Google Sheet. The intended use is outdoor, so the device can only be battery-powered. It turned out the popular NodeMCU boards are not very power efficient, and only last for a couple of weeks before the batteries run out.
After a bit of research, I made the data logger using ESP-12F (a variant of ESP8266). It has amazingly low power consumption, only 20uA in deep sleep mode. Uploading one data point every hour, it is predicted that the data logger can run for more than a year using 2 AA batteries.
The data logger has been working well for a few weeks. The only thing that is still desired is a nice enclosure. Feel free to share if you have a design!”