Isn't it time we had a standard to compare the ranges claimed?

[cwah]

Most motors and controllers have similar efficiencies, althought the efficiency of the motor varies a lot with speed, so, if you have a motor capable of 20mph and you ride around at 10mph, you'll probably be making as much heat as motion with your motor and that will compromise your range.
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Thanks for this explaination Dave.

So what would happen if the motor is give 20mph max speed at 36V, and that you double the voltage (74V) in order to reach higher speed? Would I loose a lot on efficiency too?

 

[Deleted member 4366]

What happens when you use a higher voltage is that the efficiency curve spreads out a bit because you can go faster. When you run at say 1/2 throttle, it tightens right up, so then it becomes more important to match your speed to the motor. If you use the Simulator, you can see what happens to the green curve. As an example a 20" wheel 36v Ezee motor at full throttle has an efficiency of 78% at about 16mph. At half that speed (8mph) it drops to about 64%. Run it at 48v and peak efficiency is 78% at 21mph and at half that speed (10mph) it's 67% and at 8mph about 60%. When you reduce the throttle, the whole efficiency curve tightens up drastically as if you've reduced the voltage. So running at a higher voltage has a wider spread of efficiency and is likely to be more efficient as long as you have enough power to maintain the higher speeds.
ebikes.ca Hub Motor and Ebike Simulator

 

[cwah]

Thanks Dave. Nice explaination.

I'm now aiming at high torque setup in order to quickly reach the peak efficiency.

ps: BTW, I just purchased the cute-128 for its nice price. If I melt this motor it wouldn't be too bad for a first try