http://forums.trossenrobotics.com/tutorials/how-to-diy-128/cheap-battery-monitor-using-resistive-voltage-divider-3264/
(http://postimages.org/image/3zqx20vbz/)
(https://ibb.co/fHK25J3)
(https://ibb.co/C6HZM7Y)
https://theiotprojects.com/battery-status-monitoring-system-using-esp8266-arduino-iot-cloud/
https://youtu.be/9wG1noM9PQI