Yes, two AA batteries at 1.5v each would equal only 3 volts when connected in series. The Arduino needs 5v so [AI] decided to use a MAX756 DC-to-DC step-up regulator to maintain a steady stream of 5v.

What do you do if even the smallest Arduino boards (or their clones) are too big for your homebrew project? If you're Johan Kanflo, you find a way to make them even smaller. His AAduino project ...

Mad scientist shrinks Arduino to size of an AA battery Haje Jan Kamps 2:30 PM PDT · April 19, 2016 ...

The Qduino Mini is the first tiny Arduino compatible board that has a built-in battery charger and fuel gauge, watch the video below to learn more from its creator Quin.