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 Build a Remote Kill Switch
Learn how to build a wireless controller to kill power when things go... sentient.
IoT Power Relay
Using the ESP32 to make a web-configured timed relay.
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!
SparkFun RTK Express Hookup Guide
Learn how to use the enclosed RTK Express product to achieve millimeter level geospatial coordinates.