Summary

The Arduino IDE and boards make it very easy to design and prototype a circuit, and even build a circuit to do something useful. But what if you've got a circuit you need to run off batteries? It turns out that part of the Arduino's flexibility also means it uses more power than a dedicated circuit might. In this article, we've give you a few ideas about how you can tweak your 'duino to use less power, and hopefully run longer. For most of the things we're going to show you, we're going to use the Uno running an 'empty' sketch, so you can easily try these experiments out for yourself on a bare Uno board. Of course an Arduino that does nothing isn't much use, but some of the software power reduction options will disable some functions- it's about what's going to work with your application.

If you want to estimate how long your project would last, you need to know the capacity of your batteries in mAh (milliamp-hours), and how many milliamps of current your project uses. For example, a project that uses 50mA running from a 2000mAh battery (typical for some NiMH rechargeables), it would be expected to run for 2000/50 or 40 hours. This is only an estimate, as all batteries and all circuits tend to vary slightly. If it's a critical application, it's probably worth testing.