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.
Measuring Internal Resistance of Batteries
Classroom STEM activity that has students build a battery from a lemon, measure the open and closed circuit voltages, and determine the battery's internal resistance.
Hookup Guide for the SparkFun RedBoard Artemis
Get started with the RedBoard Artemis - all the functionality of the SparkFun Artemis module wrapped in the familiar Uno R3 footprint
ATX Power Connector (4-Pin) Breakout Hookup Guide
Do you need to power a project with 12V and 5V from one wall adapter? The ATX power connector breaks out the standard 4-pin computer peripheral port for your 12V and 5V devices!
Power Delivery Board - USB-C (Qwiic) Hookup Guide
This guide will go over how to use the USB Type-C Power Delivery Board.