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What is limiting my RPMS (VESC 4.2 / Q100H setup)

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nckbutler
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Last seen: 9 months 1 week ago
Joined: 2020-02-26 16:16
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What is limiting my RPMS (VESC 4.2 / Q100H setup)

Hi everyone -

I am building my first ebike and I have everything working (I think), but am running into an issue where the motor will not go above a certain RPM even with 0 load. I cannot determine what the bottleneck is and it is driving me crazy. As far as I can tell, the VESC is running below the ERPM Limits, and the current limits, and the temp limits, so I do not understand why it does not continue to accelerate.

Motor: Q100H - 201 RPM/36V motor - I believe it has 16 poles ( https://bmsbattery.com/motor/631-16312-q100h-36v350w-rear-driving-ebike-hub-motor-ebike-kit.html)

Controller: Flipsky Vesc 4.2

Max physical RPM during testing no load: ~230 RPMs

Vesc app ERPM during testing no load: ~22,000 ERPMs

Amperage during test: ~0.5 Amp

Battery Voltage: 36V

These stats makes sense to me from a sanity check: 12x reduction ratio x 230 RPM x 8 Pole Pairs = ~ 22K ERPM.

 

lthough this top speed will be fine for me (I think it would be roughly 30 km / hr with a 700C wheel), My concern is mostly that the motor is topping out at this speed with zero load and I want to understand what is driving the limit.

Any help or insights would be much appreciated!

socrace
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Last seen: 5 months 14 hours ago
Joined: 2019-12-25 02:17
Posts: 2

According to the website, your motor is running at the expected Kv. Here's one description of it: https://en.wikipedia.org/wiki/Motor_constants