A very simple way to power Arduino

A simple and inexpensive solution is to use a 'mobile power bank', which is now widely available at low cost (from 5 €). The capacity of these systems is very high, almost always greater than 2000mAh, although some Chinese manufacturers print values ​​little true, as is the case for the batteries.

It is used to give energy to our smartphone or tablet, in cases in which our cellular battery is discharged or we can’t use the electricity grid. These devices incorporate, in a small volume, one or more rechargeable polymer battery, a charger (5V to 4.2V) and a step-up switching power supply to generate the 5V output from 3.6 V battery.

Normally it has two USB connectors female: output type A to power the phone or tablet and a micro USB for charging the internal battery, it connects to a normal power supply 5-5,5V 1 or 2 A, which is now a standard for the last generation mobile phones o tablets.

Usually they are provided of one or more cables to adapt to phones and tablet, typically with the micro USB or with standard iPhone connector. With the cable terminated with USB Micro, we can supply different cards, including Arduino Due, Yun, Nano and Teensy.

To power Arduino Uno we need a common USB cable A / B USB, like that used for printers.

This type of power supply is particularly suitable for portable and very compact systems, and it has an operating time of several hours. I use these devices for some years.

The photo below shows an example of an application with Arduino Yun.

With the experience of a few years of use of the power banks, may I suggest that you preferably use those that have a power switch. They cost more but do not have an internal consumption that significantly reduces battery life. In some cases I measured a battery discharge current of about 2 mA without any external load.