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.
FemtoBuck Constant Current LED Driver Hookup Guide v13
The FemtoBuck board is a high-efficiency, single-channel constant-current LED driver.
Hobby Servo Tutorial
Servos are motors that allow you to accurately control the rotation of the output shaft, opening up all kinds of possibilities for robotics and other projects.
Nuclear Battery Assembly Guide
How to put together your BYOT (Bring Your Own Tritium) Nuclear Battery Kit!
SparkFun Qwiic Dual Solid State Relay Hookup Guide
A Hookup Guide to get you started with the SparkFun Qwiic Dual Solid State Relay.