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I'm trying to understand the specifications of a brushless motor which I would like to buy for making an E-bike. Here are all the specs if have about the motor I'm interested in (copy-pasted from the product page):

         Voltage: 60V
           Power: 2000W
     Rated Speed: 5800rpm
      Max Torque: 4-5 N.M
Electric Current: 40A

So let's assume I have it connected to a controller which is powered by an unlimited power 60V power supply. Can the motor consume more than 2000W of power if I vary the load I give to the motor or is it the maximum that the motor is gonna pull? Thanks!

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  • \$\begingroup\$ 60V*40A = 2400W so it's likely that the power is a output power rating \$\endgroup\$ – ratchet freak Oct 1 '17 at 20:07
  • \$\begingroup\$ 2000W is only 3.29N.M @ 5800rpm, so the specs aren't directly comparable. 40A may be current at max. torque which is above the continuous power rating. And 2000W may be the rated input power, not output. \$\endgroup\$ – Bruce Abbott Oct 2 '17 at 1:36
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The Voltage and DCR (DC resistance) of the motor determines the maximum stall current and power drawn by the motor and rated current is much less than this at rated speed. \$P_d{_{max}}= V^2/DCR\$

Back EMF rises with RPM so current drops with a fixed load, but current depends on torque which is max at 0 RPM and full voltage, so a soft start is necessary to prevent excess heat 2000W at room temp and less power at elevated ambients. Motor cooling will help.

It may be capable of drawing perhaps 10x the power at 60V stall speed but unable to dissipate the heat. Thus a well designed controller is recommended with thermal monitoring of batteries and motor.

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