

How to run Arduino on a 9v battery for weeks or months - outworlder
http://hwstartup.wordpress.com/2013/03/11/how-to-run-an-arduino-on-a-9v-battery-for-weeks-or-months/

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simonhn
I also found the following article invaluable when building my ATMEGA328-based
project using watchdog timers and a battery.

[http://donalmorrissey.blogspot.de/2010/04/sleeping-
arduino-p...](http://donalmorrissey.blogspot.de/2010/04/sleeping-arduino-
part-5-wake-up-via.html)

There is some cumulative error (maybe one second per hour) after sleeping in
increments of 8 seconds (the longest interval possible with the watchdog
timer) because of the time lost starting up and shutting down, so this
approach is not 100% accurate.

Running direct from 3xAA batteries (=4.5V) means that you can avoid a voltage
regulator from 9V too.

