ESP8266 Community Forum

It is not just any "Lithium Ion" rechegable battery, it depends on the detailed chemistry.
The one that is "good" for 3.3V projects is LiFePO4 (emphasis on "Fe" instead of Mn or Co)!

We are currently working on a water leak detection system using nodemcu esp8266 and currently finding for an appropriate and best way to add power supply. Upon reading here, I have found rechargeable lithium batteries are good. May I ask how those batteries are gonna be connected to the nodemcu? I hope someone may help.