Power Supply Planner

Add up the current of all components that are on at the same time, add a margin, and choose a power supply that comfortably provides that. The values in the list are guideline values: check the specifications of your own component and adjust the number. The current draw of an ESP32 depends heavily on wifi: there are short peaks during transmission, and a weak power supply or long, thin wires then cause voltage dips and unexplained restarts.

A linear regulator (such as the AMS1117 found on many boards) converts the voltage difference into heat: (input − output) × current. If you power 3.3 V from 12 V, it will heat up quickly; use a switching converter (buck) instead. A USB 2.0 port normally delivers up to 500 mA; a phone charger usually 1 A or more. Read more about the power consumption of a battery device with our Battery life tool, and which pin does what is listed in the pinout.