ESP8266 Voltage Regulator For LiPo and Li-ion Batteries | Random Nerd Tutorials
Waterius - Hackster.io
Design your own ESP Board for Battery Powered IoT Applications
GitHub - frolswe/esp-battery-logger: Simple project for the esp8266 using the power saving features of the chip to test the possibility of battery powered sensors.
GitHub - tzapu/DeepSleepDHT22: Battery Powered ESP8266 WiFi Temperature and Humidity Logger