64 What is the Ideal Battery Technology to Power 3.3V Devices like the ESP8266? - YouTube
Amazon.com : 2 Pack - Replacement for Pentaxist D Battery - Compatible with Pentax CR-V3 Digital Camera Battery (1300mAh 3.3V Lithium-Ion) : Electronics
3.3V Lithium-Ion-Cell Buck/Boost Supply Requires One Inductor | Analog Devices