ESP8266 Community Forum

This has probably been asked/discussed before, but I am still going to ask.

I know the datasheet says the esp runs on something like 3-3.6v and thus a 18650 battery with 4.2v would damage it. If not immediately, then over time.

I thought I would do some simple tests and connected 5 esp8266 to 5 different power supplies, all giving 4.2v.
Now they have been running 24/7 for over 1 week. All esps have oled displays connected which simply shows the "time since on" time, thus giving the time since the last reboot. So far, all the ESPs are just fine. Does anyone on this forum have a case where the ESP ACTUALLY got damaged by running on a 18650 battery? I know my test-case is pretty simple with a small sample set, but are people just claiming it will not work based on the data sheet or people actually tried?

Keep in mind that my test with running 4.2v 24/7 for days is A LOT worse than it would be with a 18650 battery as it will quickly go down to it's nominal value of 3.6v.

So, please, did any of you damage your ESPs due to "over voltage"? And if you did, what voltage did you use and how long time before it broke? Thanks!

There are a couple of known instances, like this one from a couple of months ago.

Great thing with that post is that it includes pictures of a "Worn out" ESP due to overvoltage.

QuickFix wrote:There are a couple of known instances, like this one from a couple of months ago.

Great thing with that post is that it includes pictures of a "Worn out" ESP due to overvoltage.

Ok, so 5v is probably not a good idea then. However, still no evidence of 4.2v making damage
And as far as I understand from that post, he is applying 5v to one of the PINs. He is not powering the board with 5v.

I'm the kind of person that follow the rules set by those that are knowledgeable; I'm not an anarchist.

For the power requirement, the "Rules" state:

ESP FAQ wrote:4.1 What are the general power supply requirements of the ESP8266?

Digital voltage requirement: 1.8 V - 3.3 V
Analog voltage requirement: 3.0 V - 3.6 V (The lowest possible analog voltage is 2.7 V.)
Peak analog circuit current: 350 mA
Peak digital circuit current: 200 mA
Note: CHIP_EN works at 3.0 V - 3.6 V, please use a level converter to ensure compatibility
with digital logic at 1.8 V.

And, throughout the document, they are pretty strict about it.
Not far further in the FAQ, about powering the ESP using batteries:

ESP FAQ wrote:4.4 Can I use a LiPo cell or 2xAA cells directly to power the ESP8266?

2xAA batteries can power up the ESP8266. Li-Po cells have a higher voltage swing while
discharging and therefore must not be used to power ESP8266 directly.
The ESP8266 contains precision RF circuitry which is affected by temperature or voltage
drifts.
Directly connecting any RF circuit to an unregulated power source is NOT
recommended.
Use of a DC-DC converter or LDO regulator is highly recommended to ensure that the
ESP8266 performs as specified.

So you might get away with powering the ESP with a Li-ion cell at 4.2V (which is only the starting level), though it is absolute discouraged, since at least three quarters of the time the voltage is above the maximum allowed.