Originally Posted by
Len Todd
A flap servo has a constant demand for power (load) when the flap is deployed. To keep that flap down, at the same speed, takes a constant amount of power. If you need 30 watts to keep the flap down at any given speed and then reduce the voltage, the current needs to increase to give you the correct power level needed to match the servo's Pot to the signal resolution. Thus when you reduce voltage, current demand goes up. P=IR.
But the servo is not a constant power device. Yes, to keep power constant then if V goes down I must go up. But resistance devices don't work that way. Current is driven by the V, if V goes down, current will go down, revs go down, power goes down, the servo can't magically lower its resistance so that current is inversely proportional to V. If what you were saying is true, then if the V dropped to say 0.0000000000000000000000000001V, it would be capable of driving a huge current, whereas if V rose, it would push less current through!