ESP32 Forum

Hi guys,

This is my first time doing a project with ESP32 and I really don't know what appropriate batteries/setup to use..

I use ESP32 DevKitC Nodemcu. I have three sensors connected to it: DHT22, MQ-2, and MQ-7.

Are two 18650 batteries in series enough to run it? Or do I need to step the 3.0V - 3.7V output of the series batteries to 5V??

-Nelle

Hi,

First of all, welcome to the ESP32 world!

About the battery, it will depend on the efficiency you are looking for. Usually using a single cell battery with a booster to step up to 5V with 1S charging circuit, is the easiest solution but not the perfect for energy efficiency.

For the batteries in series, you will need a 2S charging circuit and the LDO will heat (loose energy) a little bit more.

The ESP32-DevKitC is not the best solution for energy efficiency. It was designed for a generic purpose using a LDO with a dropout about 1V. This makes the dev kit not perfect for using a single cell battery on the 5V input pin, but it's possible.

Just a reminder, the ESP32 will die or will be damaged if you power with more than 3.6V directly. Do not connect 18650 battery directly on the 3V3 pin.

Sounds like you might want something like this that does it all for you.
https://www.sparkfun.com/products/18018

Firstly, thanks for replying! It's my first time using this platform and I was waiting for so long for the notification button to change but it didn't and I thought no one replied to me (I realized just now how stupid this was )

I tried powering the ESP32 with two lithium AA batteries in series through both the 5V and 3V (which I just learned that I shouldn't have done. Oops.) pins directly and both did not work. This ESP32 was supposed to send the sensors' values to another ESP32 using ESP-NOW. I have been powering my ESP32 using my laptop with all the sensors tapped to the 5V pin and it was working perfectly. When I tried the series lithium AA batteries, the sensors lit up the same way it does when I was using my laptop (which I assumed means that it gets enough voltage?) but the sensors' values weren't being sent to the other ESP32.

I haven't tried using any charging circuit and its going to be the first time using one (so sorry if I'm annoying you with my cluelessness) so I guess I'll have to play with it a bit.

For the ESP32 Thing Plus C, unfortunately, I already ordered all the ESP32s I need for this project so I just have to make do with what I have..