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Freddy Kruger

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Oct 13, 2019
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Hi, what does 750w max instantaneous power actually mean compared to the 250w nominal. How, when, and for how long would I feel the extra Watts?

Thanks

J

Specifications
MotorShengyi DWG22C. Compared to the Bafang SWX02, the Shengyi motor is 0.5kg heavier but has stronger torque at low speed.
PowerNominal power: 250W
Maximum instantaneous power: about 750W
CassetteCompatible with all Shimano cassettes
7-speed cassette needs 3mm spacer
Rear dropout135mm (can also fit 140mm dropout)
VoltageDC 48 Volts
Limit current (max. continuous)17 Amps
Motor WeightBafang DWG22C: 4.5kgs, 5kgs total with rim and spokes
Rim26" double-wall with 13G stainless spokes
Disc brakes compatibilityYes, standard 6 bolts for 180mm/203mm rotor mounting



it's basically a clone for the Bafang BPM CST.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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You will notice the extra watts (up to 750w ) on inclines in assist level 5 or with a throttle, it will be pretty effortless. Controller is 20a rated x 48v nom voltage gives 960w total out put but by the time you factor in wiring/hub efficiency the power at the hub wheel is actually about 750/760 watts which is a mega healthy boost if needed, or about twice the watts a TDF or pro rider outputs and they are the elite.

The 750w though isn't a continuous power rating but a temporary one typically for 20/30 sec burst of power, though in most cases you could get a way with a little longer but not continuously as power will add heat and could cause hub damage to the nylon gears. The nominal 250w is the rating it will run at all day long which is typically in PAS1, 2 or 3 depending on the controllers current settings.
 
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sjpt

Esteemed Pedelecer
Jun 8, 2018
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You would feel it most going up a not too steep hill, and maybe acceleration.
(I think, but others may correct that.)

On the flat it should cut out at at 15.5mph, where you wouldn't use the power.
On a steep hill you could not keep going fast enough for the motor to generate its full power.

I'm not sure how long a motor can keep generating that sort of power without overheating.
The battery may well not like trying to output that sort of power either.

You can get some idea of how motor power/speed/efficiency works from https://www.ebikes.ca/tools/simulator.html
but it is sadly missing many modern motors.
 
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Nealh

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On inclines esp steeper ones as mentioned you won't get max speed unless you are a TDF rider and your cadence is over 90/100 rpm but what you will get is max power at a lower speed and torque.
 
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1boris

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Sep 10, 2013
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The 48V 250W DWG22C is made by Shengyi, the road legal version of their DWG22 made for us, direct replacement for the 48V SWX02 that we sell but with a cassette fitting:

http://www.syimotor.com/productDe_3.html

The shipment arrives in a few days. I'll post it on the website after checking.
Hi,
What is the no load rpm of the Shengyi DWG22 motor? is it more silent than Swx02 motor?
 

Laser Man

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Jul 1, 2018
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Michelmersh SO51
Bump. @Woosh , do you have a link for the DWG22C with the 17a battery? In 700c/29er rim. Had a quick look and cant find it, dont want to mess up
36V 17Ah battery stores 612 Watt/hours of energy
48V 12Ah battery stores 576 Watt/hours of energy

So the 36V 17Ah does have the edge, but not by a significant amount - you would get about the same mileage from either.
 

Woosh

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May 19, 2012
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Hi,
What is the no load rpm of the Shengyi DWG22 motor? is it more silent than Swx02 motor?
Hi Boris,

very similar to your 48V SWX02 but a little quieter.
The main thing is it has a freehub body for cassettes.
 

Woosh

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It has the same winding but I forgot to check on the test bike, now I have run out of batteries until 15-July so I can't confirm the noload speed to you until the new shipment arrives.
 

Nealh

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May be selling components would be another feather in the cap esp selling lower wound/rpm high torque hubs that one can't buy below the 201rpm models.
 

Woosh

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I would need more manpower and storage space.
Are you offering your services for kit advice and support?
 

Nealh

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I'm trying to slowly retire Tony and as it is not enough hours in the day.
 
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