Now, after two weeks of vacation, the sensors were in operation from 2016-05-17 until now and the battery condition is very well. This means an uninterrupted run time of 28 days until now.
You can follow the status of this IoT Node at www.ckuehnel.ch/AM2315@NodeMCU.html. Here is a screen shot of today’s results.
This ESP8266 IoT board combines built-in USB and battery charging. The ESP8266 is clocked at 80 MHz and supports 3.3 V logic.
To make it easy to use for portable projects, a connector for 3.7 V Lithium polymer batteries and built in battery charging was added.
You don’t need a battery, it will run just fine straight from the micro USB connector. But, if you do have a battery, you can take it on the go, then plug in the USB to recharge. The board will automatically switch over to USB power when its available. The board comes pre-programmed with NodeMCU Lua.
You can order this ESP8266 IOT Board [DPO82666E] from ELECROW for $12.90. Further info you will find in the ESP8266 IoT Board Wiki.