In this episode I show how a ESP-07 or ESP-12 measures its voltage and transmits it to data.sparkfun.com and ubidots.com. If it transmits every 2 minutes, it ran 26 hours on a small LIR2450 button cell. If it would transmit each hour, it would last for 17 days and on 2 AA batteries 425 days. Sketch: https://github.com/SensorsIot/ESP8266-Longterm-Sensor-Hourly Rainer Ochs: http://www.esp8266.com/viewtopic.php?p=41638 Base64: https://www.base64encode.org/ HT7333 voltage regulator:http://s.click.aliexpress.com/e/ciskloDS Official Wemos Store: http://s.click.aliexpress.com/e/jUzBiIq Calculator to calculate running time: http://battery-life.of-things.de/battery-life-calculator.php or https://batterylifecalculator.iobot.in/ If you want to support the channel and buy from Banggood: https://bit.ly/2jAQEf4 (no additional charges for you) https://www.facebook.com/Andreas-Spiess-733189426841519/ https://twitter.com/spiessa