It all started with trying to power an Arduino Due with 0.38V available from VGA monitor.
My searching for 5V step-up converters showed lots of converters that work with 0.9V and higher. The only converter I found that works with 0.5V-5.5V input range was this Polulu converter:
These are the most interesting sentence from U1V11F5 description:
The input voltage, VIN, must be at least 0.5 V for the regulator to turn on.
However, once the regulator is on, the input voltage can drop as low as 0.3 V and the 5 V output voltage will be maintained on VOUT.
This seems to allow to drive Arduino Due with 0.38V once system has started (somehow), this will be the next thing I will try.
Yesterday I played with Arduino Uno and LCD Keypad Shield. Therefore I just connected a single 1.52V AA battery with U1V11F5 and that with Arduino Uno with shield, and all just worked!
The converter gives 5.09V:
I thought it might be interesting to know that you can power Arduino with 0.5V,
Hermann.