NodeMCU board powered by single cell LiPo battery and solar cell.
Programmed using Arduino enviroment.
Each 30 seconds the module wakes up read the battery voltage before turning on WiFi and send the values.
ESP8266 running NodeMCU with a DHT11 to report humidity and a BMP180 to report pressure and temperature. The Sensor also reports battery voltage which is 2xAA batteries. Photo: http://imgur.com/hDpeNxj
Monitors the pool and air temperature using an Arduino Pro Mini, ESP8266 WiFi chip, and a couple of DS18B20 temperature sensors.
Samples and transmits the temperatures every hour.
Running off a 500mAh lipo