Torque and RPM Graph for Castle Creation products ?

[Pdelcast]

Originally Posted by SpEEdyBL

2. The equation for % efficiency of a motor is (VI - rI^2 - I0)/(VI) where V= volts, I = amps, r=resistance and I0 = amps at no load. So if you plot the graph as % efficiency vs. amps, you will see that if you use a higher voltage constant, you will get a higher max efficiency. But keep in mind this is only a theoretical equation and at some voltage, the efficiency starts to get worse. This voltage where peak efficiency is the highest is known as the sweet spot of the motor.

That equation only models electrical losses -- not magnetic losses (magnetic losses are lumped in with the IO constant...) Keep in mind that magnetic losses are non-linear (especially at high power.) Also, the IO constant needs to be measured at the same RPM as the output -- because other losses (like windage) are also non-constant (windage losses are RPM cubed...)

[othello]

Great information. Thanks to both of you.

>Pdelcast: It would also be the same if you doubled the number of poles and kept the winding the same...

Meaning: The simple saying that a 2 pole motor "has" more torque than a 4 pole motor is simply wrong giving the same windings and rotor size. This is what i thought as you can not pack more magnetic material on the same rotor.

[SpEEdyBL]

Originally Posted by Pdelcast

That equation only models electrical losses -- not magnetic losses (magnetic losses are lumped in with the IO constant...) Keep in mind that magnetic losses are non-linear (especially at high power.) Also, the IO constant needs to be measured at the same RPM as the output -- because other losses (like windage) are also non-constant (windage losses are RPM cubed...)

Thanks Patrick. Whoops, forgot to multiply I0 by V, but oh well, its only a theoretical equation that will result in a graph similar to the one posted. I knew there were other variables of some sort. Otherwise it makes feigaos seem really efficient!