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.
Beefcake Relay Control Hookup Guide
This is a guide for assembling and basic use of the Beefcake Relay Control board
Adjustable LiPo Charger Hookup Guide
The SparkFun Adjustable LiPo Charger is a single-cell lithium polymer (LiPo) and lithium ion battery charger. Because it’s adjustable, this charger will be able to safely charge all of our singe-cell batteries.
12V/5V Power Supply Hookup Guide
In this tutorial, we will replace the 12V/5V (2A) power supply's molex connector with two male barrel jacks adapters.