What is the effect of wrong voltage to ESP32

Projects General Guidance
1

This is a totally beginner question. I always use USB to power my ESP32, but now I need to use external battery. I use Volt Meter to check the battery and it shows 3,8V. I have read that Vin pin can accept 5V. I put 3,8 and ESP light up. ESP connected to display, and the display seems to light up as well. So, what will happen if I put 4,2V ad Vin? Is it going to cause some trouble?

Note:
I need to make a small device. I need to use SIM808 module that work on 3,5-4V so I thought about using step-up module. But the device only has space for 1 Step Up/Down module. So I either use it for SIM808 module or for the ESP.

Any suggestion are welcome. Please help me with this

2

You'll need at least 3.2V for stable operation - how ever you do that. Depending on your board you can go up to 5.2V or 6V.

3

I found this at datasheet:

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image716×347 45 KB

And after recheck, I found that my battery is 3,8V. And SIM808 need from 3,5 to 4. Is it a good idea to use step down and set the voltage to 3.5 so I can just plug it to both?

4

And what if it's over voltage? would it break?

5

Yes.

6

depending on the ESP32-board you are using.

If it has a USB-socket. USB always uses 5V. If there is a USB-socket then there is a voltage-regulator on the microcontroler-board that does regulate down to 3.3V.

You can connect 5V to the Vin-pin.
But only to the V-In-pin.
All other pins should be only connected to 3.3V (or a maximum of 3.6V)
So applying 3.8V to the 3.3V input pin of the ESP32 will destroy it.

a voltage-regulator needs a voltage that is minimum approx 1V higher than its output voltage
If your battery goes below 3.8V it might be that using the V-in does not work because of the then too low input-voltage for the onboard voltage-regulator

What type of battery are you using? What will be the lowest voltage before battery is too empty?

If you want to operate an ESP32 on battery as long as WiFi is switched on the battery will be empty after some hours. WiFi is power-hungry.

The ESP32 has a deep-sleep-mode. But most ESP32-boards are not optimsed for lowest deep-sleep-power-consumption. The current will still be in the range of 7 to 15 milliampere

There is only one manufacturer of ESP32-boards that gets
the deep-sleep-current down to 0,015 milliampere

best regards Stefan

7

Wow thanks for the info. I use 802025 200mAh battery. I don't think this battery can last long, but I only need it to last like 10 mins, just to show it to my teacher :melting_face:

8

oow and, can you give suggestion about what LiPo battery that can give 2A current? cause SIM module can draw 2A peak current...

9

What C-rating does your 802025 200mAh battery have?

If this is a battery that is usually used in a model RC-car or a model RC-plane it will have 15C or 20C which means:

15C maximum dis-charge current 15 times x capacity
20C maximum dis-charge current 20 times x capacity

15C x 0.5 Ah = maximum dis-chargecurrent 7.5A

I suggest you use a 500 mAh 20C Lipo.
As I don't know in which country you live in I can't suggest a real product

10

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