I recently took part in a challenge called 'Hydrogen Hack' where we have a Raspberry Pi and have to make something controlled by that. The catch is that it has to be powered by a Hydrogen Fuel Cell - each fuel cell has a USB style output of 5 volts at 1 amp. This is enough to run the Raspberry Pi (we have tested) and draw 5 V off the 5 V GPIO Pin.
However, the minimum voltage our motors can run at is 8 V at 1 A but preferably we need 12 V 1.5 A as the faster the motors spin the better and the H-Bridges we are using draw some power (obviously).
Me and my friends have come up with a few ideas but all of them seem impractical, we need to draw the 8 V 1A (or 12 V 1 A) for around 20 seconds preferably but this could be shrank to 15 seconds again if necessary.
I was wondering if any of you guys could come up with some ideas as to how / if we can do this?
Pi Input: 5 V 1 A
Pi GPIO 5 V Output: 5 V 200 mA
Power build up: 8 V 1 A for 15 s but preferably 12 V 1 A for 20 seconds
I have googled and cannot really find anything relevant to what we need as it is probably silly to think anyone will of done this and bothered to document it before.
The power loss in the L293D is aprox.: (1.4V + 1.2V) x 0.6A = 1.56W
The motor preferably needs: 12v * 1A = = 12w
Wattage available: 1w
So i firstly need a way of converting the 1w to 13.56 and then storing it
And by the way, You cannot use any other batteries but they did not specifically rule out capacitors.