batteries - Is it safe to use ESP8266 with 3.7V?

I am using an ESP8266 WiFi module in a circuit. The battery is 3.7V. Is it safe to give the ESP8266 (3.3V) directly without a voltage regulator?

Answer

Also note that that battery is 3.7 V nominal voltage. Fully charged it will probably be 4.2 V. Way too much for the ESP8266. Conclusion: you need a voltage regulator.

Look for a buck boost regulator like this: -

Or this: -

Or this: -

Or this: -

Or this: -

Or try googling "low power buck boost 3.3 volts 150mA" yourself

EDIT SECTION

A really small device is this (3 mm x 3 mm package): -