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.
Beefcake Relay Control Hookup Guide
This is a guide for assembling and basic use of the Beefcake Relay Control board
ESP32 Thing Power Control Shield Hookup Guide
This tutorial shows you how to get started with the ESP32 Thing Power Control Shield.
SparkFun Qwiic Dual Solid State Relay Hookup Guide
A Hookup Guide to get you started with the SparkFun Qwiic Dual Solid State Relay.