ESP8266 Community Forum

Hi. I am wondering about the max current draw from the 3.3V pins. I refer about the 3.3V pins only, not the digital/analog pins.

An exaple: Is it possible to power a 3V 0.5Amp device, using 'Nodemcu esp-12e' 3.3V and GRD pins as power supply? An then power the Nodemcu with a 12V battery, for example.

You should read the part number of the voltage regulator (VR) on the board then find the datasheet. The datasheet should spec max input voltage, max output current, etc. There is a NodeMCU schematic on github but there is no guarantee that all the companies that build NodeMCU boards use the same VR.

You will need to take into account the current requirements of the ESP8266. You would have greater external load capacity if the external circuit did not draw as much power when the ESP8266 draws it's peak power. From what I read the peak power required happens when the ESP8266 does a calibration cycle.

I had tried to power the ESP-12E with a 250mA rated regulator and mostly it worked. Mostly isn't good enough for me. I had to go to a regulator with a higher current. Just adding capacitance to cover the higher surge current was not enough. (I thought it would have been sufficient)

What I would strongly suggest is powering the external circuit with it's own regulator. This would prevent disruptions from affecting the ESP board. If you are going to power the Nodemcu board with 12 volts you need to consider the power dissipation of the regulator. The regulator would be dissipating almost three times the power that the ESP-12 will be dissipating.

Consider using an efficient switching regulator. It will run cooler and not waist as much power generating uselesd heat.

Check the specifications for the components you will use and do the math. Then test.

If I'm not mistaken, an ESP12 peek-usage is about 550mA (@3.3V). I don't remember exactly when this happens (I though it was about "calibration"). It's the reason why the onboard power-regulators should be able to handle about 600 mA minimum.