Reducing Arduino Power Consumption
Contributors:
Alex the Giant
Alex the Giant 
Resources and Going Further
More information on low-power modes and options can be found in the datasheet for the 328P.
For more power-related fun, check out the following SparkFun tutorials.
IoT Power Relay
Using the ESP32 to make a web-configured timed relay.
Buck-Boost Hookup Guide
This tutorial shows you how to hook up and use the SparkFun Buck-Boost board.
Power Delivery Board - USB-C (Qwiic) Hookup Guide
This guide will go over how to use the USB Type-C Power Delivery Board.
Breadboard Power Supply Kit 5V/3.3V Quickstart Guide
Quick start guide for the Breadboard Power Supply Kit 5V/3.3V