Powering ESP32 Dev Board from the BMS

Other Hardware 3rd Party Boards
1

Hi there! I have a problem with powering ESP32 Dev Board from the BMS and 18650 battery

I use HW373 BMS connected to the ESP's VIN and GND pins via OUT +/- pins. But instead of working normally, is seems like ESP is restarting constantly. I guess it's because that kind of power source is unstable for ESP's brownout detector. How can i make the whole thinkg work? Maybe use a capacitor?

For the context: i am not an expert hardware engineer, it's not my primary field, but i need to find a solution asap

2
  • Monitor the ESP input voltage to see if it sags.
3

What board? What model of regulator does it have?

Many boards use AMS1117-33 regulator. These claim to be "low drop-out" but maybe the drop-out is still too high for it to output a steady 3.3V for the ESP32 chip.

An external and truly low drop-out regulator could be used to power the board through it's 3.3V pin. For example MCP1702-33 or HT7333. But you need to consider how much current is needed at 3.3V by your board and any other circuits it powers.

4

Seems like mine got 117C voltage regulator

5

It still has more than 1V dropout voltage.
Did you try with 100% charged battery and nothing powered from Esp pins?

6

An 1117 VR has a 1.3V loss, so the input must be 1.3 + 3.3 which is 4.6 and is 0.4 more than the 18650 can supply. Use two 18650's in series.

7

I am not connecting directly to 18650, It's connected through BMS OUT pins. Aren't they supposed to give enough voltage?

And i cannot connect two 18650 in series, it'll kill my BMS (trust me and my previous bms killed this way)

8

It's direct battery voltage anyway. 3.5-4.2V. And the voltage regulator needs ~4.4V to work like it's designed.

9

Ok, got it. What should i do then? Use DC-DC StepUp?

10

That's one option, another option was well described on post#3.
It depends on your load, do you power just Esp or some other components attached?

11

Bye

12

What BMS, I don't see a BMS in the diagram. Oops, that's right you didn't provide one along with datasheet links for each component.

13

Why, what happens if it takes a week to find a solution and source parts?

14

I also have a bunch of sensors attached (GY-21 HTU21, Capacitive Soil Moisture, INA219). Just checked their datasheets, they should work fine with 3.3V. But i also need to power a motor and water pump, and i am not sure how they'll operate from 3.3V (I'm not goind to power them throug ESP directly tho)

15

I need to submit the project with the deadline being 17 March

16

Buy a 4 AA battery pack. Connect it to ESP Vin and use it to power your motor and water pump.
Forget the BMS

17

ESP-WROOM-32 Dev Board
HW373/TP4056 BMS (info here)

18

It would be nice, but the device must be rechargable, swapping batteries isn't an option :frowning:

19

Then use 4 or 5 NiMH batteries.

20

You could use ultra low dropout voltage regulator for your Esp and low-power sensors and power motor/pump directly from battery (TP4056).