Comparing two Electric Scooter Motors

Hello experts,

Also am an electronics noob, so apologize in advance if this is too basic.

I have 2 motors from 2 brands.
These are BLDC In-Hub Motors for an Electric Scooter (2 wheelers - not toys you see in curbs of American cities!!)

One claims a rated power of 1000 watt and peak power of 2500 watt, Gradebility of 22 degrees. This uses a 72V system.
Another brand says they have a motor rated at 1000W with a Peak power of 1500W and claim Gradebility of 7 degrees and this uses a 48V system.

Both use a 2 kWh battery packs.

Now how do i arrive at the power (in kW - don't care bout antiquated HP) that will be generated by each motor at say 2000 RPM
And how do i arrive at the Torque at the said RPM.

Apart from Power at RPM and Torque at RPM, what other parameters do i need to look for while comparing the two.

How do we trust their grade-ability claims?

Thanks in advance!

-Test unloaded speed of wheel at full throttle (noload rpm) and at what voltage you measured it.

-Divide it to rpm/volt which is called voltage constant: kV

From this calculate torque constant kt:


Next check max current: Imax of the controller

Max system torque Tmax is kt*Imax

Torque Tx at a certain rpm is roughly:
Tx=Tmax*(1-rpm/noload rpm)*0.85
(Where the 0,85 is an assumption for the efficiency at higher rpm)

Power at certain rpm is roughly Tx*rpm/9.55
(Tx is given in Nm)

(Or you check with wherever you got the motors and do some googleing)
Good luck.

kamyfc said:

Now how do i arrive at the power (in kW - don't care bout antiquated HP) that will be generated by each motor at say 2000 RPM

Click to expand...

If it's a hubmotor, it's probably not designed to run anywhere near that speed, usually just a few hundred RPM max.

If it's meant to run at say, 300RPM at 72v, then to get 2000RPM you'd have to run it at 480v. (2000 / 300 * 72)


It's possible that eddy currents / etc in the motor at the higher RPM will create heating problems inside it.


It won't help with your specific motors, but you can learn a lot about comparing different motors over at http://ebikes.ca/simulator .

Correct there AW, 26" wheel at 2000rpm is 240km/h or 150mph!

Didn't think of that