I was testing the deep sleep mode featured in the ESP8266.

I have a simple USB battery power supply associated with a 3.3V power regulator (https://www.adafruit.com/product/2165).

Everything is fine, I have a low current in the deep sleep mode.

Then I tried to power the thing with two 1.5V AA cells and eveything got messed up: my ESP keep restarting (led blinking). I both tried the ESP-01 and Huzzah from Adafruit.

I noticed two things:

(1) Input voltage drops at 2.8V when ESP is on.

(2) Input current raises over 130mA (compared to 70mA with the USB battery).

My conclusion would be that the voltage being too low, the chip trie desperately to power up at full throttle, .. and fails then reboots.

Am I right?

Edit: ESP8266 seems to be able to work ender 3.3V : http://www.esp8266.com/viewtopic.php?p=23790#p23790

What is the solution?

Thanks to you.


4 Answers 4


Modules like the ESP8266 which have no on-board regulator but do need a regulated power supply. Indeed, a power supply voltage that is too low will cause the module to reset.

What I would do in your case is get a boost module like this one to convert the voltage from the batteries to 3.3 V. On the module there's a trimmer to set the output to 3.3 V, set this BEFORE connecting the ESP8266 because such an upconverter module can easily generate 12 V which would fry the ESP module !

  • \$\begingroup\$ But how can those projects work without any regulator? benlo.com/esp8266/esp8266Projects.html // hackster.io/noelportugal/ifttt-smart-button \$\endgroup\$
    – bixente57
    Commented Oct 5, 2015 at 19:36
  • 1
    \$\begingroup\$ The button: it probably only works with batteries that are still reasonably fresh and/or maybe the ESP module is used in some low energy mode so it will not draw so much current. On the 2nd project I see a regulator on the board. \$\endgroup\$ Commented Oct 5, 2015 at 19:58

I confirm it works excellent with 2 AA batteries. I tested it with DURACELL batteries (standard batteries bought from a convenience store).

You HAVE to connect positive to CH_PD and VCC (this is key!) negative goes to GND and that's it.


Some facts about your setup:

  • The typical operating voltage of ESP8266 is 3.3V
  • Your LDO / Regulator outputs 3.3V
  • Your LDO input is 3V
  • Your LDO isn't a boost converter.

In a nutshell, you can't power the ESP8266 module either directly or using LDO using two AA batteries.

You would have to use at least three AA alkaline/lithium/Carbon-Zinc batteries. The rechargeable Ni–MH or Ni-cd batteries will barely make it as each cell is 1.2V (nominal).

A better (no hassle) solution is to buy ESP module with a battery pack like one below. It will simplify a lot of things for you. You can remove extra LEDs or sensors if you want to go low-power. esp8266


I have used some old Nokia batteries with no problem. Since they can have up to 4.2V (!?!) after fully charged, I use a diode in series to the positive.

  • 1
    \$\begingroup\$ Yes, 4.2V is the peak voltage of a charged lithium battery. 3.7V is only the 'nominal' voltage. \$\endgroup\$
    – pjc50
    Commented Feb 23, 2016 at 16:55
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    \$\begingroup\$ Great tip! Do you have an ideia on how much power is being wasted by this diode? \$\endgroup\$
    – rodvlopes
    Commented May 19, 2016 at 17:39
  • \$\begingroup\$ Be careful with the LiPo's. If their voltage drops way below their nominal 3.7V they could damage easily. \$\endgroup\$
    – papaiatis
    Commented Jun 6, 2016 at 7:24
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    \$\begingroup\$ Well @rodvlopes, what I know is that a regular diode has a 0.6v drop. As far as I have read the ESP has some tolerance and works nice at 4.2v, but I never took the time to test this. \$\endgroup\$ Commented Jun 9, 2016 at 2:47
  • \$\begingroup\$ @GiordanoBruno my experiments with esp-01 and esp-07 show they become instable when they're running above 4.0v. Sometimes it will boot up properly and sometimes not. I am also working with LiFePo4 battery and its just fine without any regulator. \$\endgroup\$
    – rodvlopes
    Commented Jun 10, 2016 at 13:07

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