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.
LTC4150 Coulomb Counter Hookup Guide
A "Coulomb Counter" is like a gas gauge for your battery. Here's how to use it.
Beefcake Relay Control Hookup Guide
This is a guide for assembling and basic use of the Beefcake Relay Control board
LilyPad Basics: Powering Your Project
Learn the options for powering your LilyPad projects, LiPo battery safety and care, and how to calculate and consider power constraints on your projects.
Power Delivery Board - USB-C (Qwiic) Hookup Guide
This guide will go over how to use the USB Type-C Power Delivery Board.