And, to power the Arduino itself (5Volts), we can use a STEP-UP device and 2 batteries cells to get the necessary 5 Volts to power Arduino via de USB connector.
A 3 pin TO92 device like the HT7750 can work from input of 1.2V cell and produce the 5 Volts…
It will work with only one 1.2V cell, but I am not sure if it can create enough current (milliamps) to run Arduino properly… 2 cells should be enough to run basic stuff with Arduino…
[Batterino is ok with 1 cell ?!?!]
The Batterino scheme (above), because it is more simple, will probably run well from only 1 Battery Cell and the HT7750 VOLTAGE STEP UP device… well, in any case it will depend on the total current that the duino and the application requires…
Valter