Nachtwind:
just some quadrocopter, nothing more ,0)
The Arduino wont have to suffer from the amperage since it is safe behind the 5V line of the speed controllers (and will get the "normal" Arduino power circuit as well). The amperage will only come from the speed controllers/motors. A car battery sounded like a good idea but i have to take the weight for this into account..
I ordered 2 11.1V LiPos and will use one at a time i guess, thats the easiest way i hope.
Is it not possible to purchase COTS ESCs for the voltage/current requirements you need/want? If I were building such a project, that's where I'd look. Also - at a certain point, gas engines become a more attractive option (well, noise and other issues aside).