This very simple project shows how an Arduino can cut off its own powersupply.

This very simple circuit allows for a momentary button push to activate an arduino. The arduino will then run for as long as it desires, but will cut off its own power on command.

This is ideal for when you want to have a single button push activate an arduino starting a program and then stop tapping the battery when it is done.

This example uses a bare board arduino but it could be pretty much any arduino.

This can wildly save battery life while the arduino awaits your next command.

The matching tutorial video:

https://youtu.be/5UenY8-2WnM