Use 12v fans for your ESC/motor...

[BrianG]

Actually, if I really wanted to get anal about it, I would have written this:

In a linear regulator, no matter what the output voltage is, the current required by the load will be the same as the current from the battery. So, 1A at 12v will be 1A from the battery whether it's 15v or 200v. This is why they are so inefficient.

In a switching regulator, it's a power transfer. 1A at 5v UBEC output would be only 0.29A at 20v (assuming switching efficiency of ~85%).

:)