WeMos D1 Mini NodeMcu 0.66" OLED Shield Battery Shield For Arduino | eBay
Power Management | Adafruit Feather HUZZAH ESP8266 | Adafruit Learning System
Buy 3V/5V 18650 Battery Shield V8 Mobile Power Bank for Arduino ESP32 ESP8266 Wifi at affordable prices — free shipping, real reviews with photos — Joom
A battery fed MQTT weatherstation – Arduino, ESP8266, ESP32 & Raspberry Pi stuff
18650 battery shield with USB or soldering 3V/5V connector for Arduino, ESP8266, ESP32 projects • DIY Projects