Tutorial 1:How to Reconnect ESP8266 NodeMCU to Wi-Fi Network After Lost Connection?----https://microdigisoft.com/how-to-reconnect-esp8266-nodemcu-to-wi-fi-network ...

Battery monitoring: the voltage of an 18650 battery is 3.7V and can go up to 4.2V when it is fully charged. The Wemos D1 mini already has an internal voltage divider that connects the A0 pin to the ...