ESP8266 Community Forum

I would like to connect a 9V battery as power supply to NodeMCU development board. Can I connect it directly to Vin and gnd instead of using USB power? Can the regulator SPX3819M5-L-3-3 handle input 9V?

I don't know the development board.
The input voltage range of the SPX3819 is up to 16V. So it would be possible to use a 9V battery.
www.adafruit.com/datasheets/SPX3819_DS_R202_052014.pdf

Take caution with input voltage!

I have a NodeMCU development board (ESP12E) with an CP2102 USB to serial TTL and voltage regulator that only accepts input voltage between 4v and 5.25v. Take a look to its data sheet:
https://www.silabs.com/Support%20Documents/TechnicalDocs/CP2102-9.pdf

In that case you will need a zener diode (for simplicity) to step down from 9v to 4.7v or (best) 5.1v. Remember that voltage difference are consumed by the limiting resistor, so it's best to choose 5,1v zener over 4,7v one:
http://www.electronics-tutorials.ws/diode/diode_7.html

Good luck

i just killed my nodemcu board by connecting full charged 9v block to the micro usb port (via selfmade adapter)
it was rated for 5-10v in but it died instantly
and i couldnt use it anymore also it startet smelling bad