No back-EMF DC motors?

[Ryland]

I might not be exact with my numbers here but they will be pretty close.

If you have a 1hp motor turning an alternator/generator that motor should be drawing around 850-900 watts and the alternator should be putting out around 600-650 watts, so if you can make a 1hp motor that only draws 100 watts then it should be able to power an alternator and produce that same 600-650 watts, but you can't, it just doesn't work that way.

[dcb]

That was a sad video, didn't demonstrate anything conclusive or useful, it didn't make the motor do any measured amount of work with a measured amount of power. Not even a diagram of the "concept". Comments are disabled because it would get torn up for being such a piece of B.S.

Without measuring both input and output power you cannot tell how efficient it is. This guy does not strike me as a scientist.

1hp=746 watts. This is not a measure of efficiency, just a conversion factor.

If the motor had zero back emf, would it not keep speeding up till it disintegrated?

Looks pretty steady state to me. Thar be back EMF in that motor.

[The Atomic Ass]

Originally Posted by The Atomic Ass

That's what I've been told, but how did science come to that conclusion? What basis of experiment returned the unerring result of ~746 watts to generate one horsepower?

Anyone mind if I bump this question?

[dcb]

Watt Watt noun [ From the distinguished mechanician and scientist, James Watt .] (Physics) A unit of power or activity equal to 10^7 C.G.S. units of power, or to work done at the rate of one joule a second. An English horse power is approximately equal to 746 watts.


He might as well argue that he is using inches that are not 25.4 mm.

[Daox]

Its my understanding that the back-EMF is not actually wasteful, it simply reduces power output. As the back EMF starts, it slows current through the coils and therefore less power is drawn during that time. The power is not lost to nothingness.

[saand]

Right you are daox,
the back EMF is also the same effect used in generators to make electricity, its not a bad thing to have back EMF

[UFO]

To boil it down conclusively, back EMF is fundamental to the electric motors operation. You cannot get rid of it and still have a motor.

[gone-ot]

...Counter Electro-Motive Force (CEMF) -- it does not matter *how* a wire is moved through a magnetic field (motor = pulled through the field; generator = pushed through the field), only that wire-through-field movement occurs.

...CEMF is *how* regeneration-charging occurs during braking.