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.
PicoBuck Hookup Guide v12
The PicoBuck board is a high-efficiency three-channel constant-current LED driver.
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.
How to Build a Remote Kill Switch
Learn how to build a wireless controller to kill power when things go... sentient.
Secure DIY Garage Door Opener
Did you know that most garage doors are at risk of a roll jam attack? Here we make a DIY garage door remote-control system that is much more secure than most commercial-ready products using the latest in ECC cryptography.