What is more efficient: 1000w @ 50% or 500w @ 100%

[jman231994]

Hey guys, not specifically asking that question, just thought it would be the best way to explain my question. What is more efficient, a larger motor at a lower throttle percentage or a smaller motor at full throttle. (Throttles probably the wrong word :roll eyes: )

So for example, as in the title, would a 1000w at 50% be more, equal or less efficient than a 500w at 100%.

This is all relating to a competition for endurance and I want to know if it would be smarter to electronically limit a bigger motor to get much better efficiency

Thanks

 

[DaiSan76]

As I understand it, the motor will draw as much current as the controller will allow it to. Now if that is true, then you would get the best efficiency from a smaller motor geared down than from a bigger motor geared up and throttled back. I have done some experimenting with this sort of thing in RC cars, and if I put a big motor into a car (keeping the same speed controller), it draws high amperage, and drains my battery faster. So what that means, is that I would use the smallest motor possible, and gear it down to keep from burning up the motor or controller.

 

[jman231994]

Thanks, but I'm pretty sure the motor will reach a current maximum assuming the controller has a heap of headroom for both. My understanding is that an electric motor is most efficient around 75-80% of full power. So let me reword my question. Assuming same gearing, voltage, battery capacity, weight and at a constant speed of 25km/hr. Would a 1000W motor provide greater battery range than a 500w motor if the 500w motor is at full speed to attain that speed and the 1000w is at whatever it requires?

In the case of an rc car, were both setups travelling at the same speed? Because from my rc car experience, a larger motor will only flatten a battery faster if it is not being run at its optimal setup. And obviously not being pushed faster than the smaller motor. In saying that, my range issues on my rc car are due to the nimh battery overheating and losing heaps of power to heat