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.
How to Power a Project
A tutorial to help figure out the power requirements of your project.
Photon Battery Shield Hookup Guide
The Photon Battery Shield has everything your Photon needs to run off, charge, and monitor a LiPo battery. Read through this hookup guide to get started using it.
Qwiic Quad Relay Hookup Guide
SparkFun’s Qwiic Quad Relay is a product designed for switching not one but four high powered devices from your Arduino or other low powered microcontroller using I2C.
MicroMod Ethernet Function Board - W5500 Hookup Guide
Add Ethernet and PoE capabilities to your MicroMod project using the Ethernet Function Board - W5500.