ESP8266 Community Forum

I know the esp8266 isn't 5v tolerant but what is the highest voltage at which it will operate reliably? What I'm specifically interested in knowing is, will it tolerance the 4.2v from a lipo battery?

Hi, thats a bit to high. I have used lipos but with a diode in series, dropping 0.7V takes it down to 3.5V and that has been fine with the work I've done.
This might not be ideal if your going to use deep sleep as the current draw through the diode will drop below the 0.7V threshold and the voltage will rise back up to 4.2V during sleep.

Data sheet says Vcc + 0.3V, so 3.6V. You would probably get away with it if you are just experimenting or making a temporary project, but reliability and longevity would be affected.

A popular solution is a series diode as suggested above (but this is problematic at very low currents). I've had success using the MCP1700 3.3V regulator for LiPo batteries - it has a dropout of only a couple of hundred mV and is very cheap. Max current is given as 250mA, but I've had no problems.

The datasheet says 3.0~3.6V.