Bafang MOTOR CHOICE-- What is going on with the Codes/rpm

[emiyata]

Bafang know exactly what they mean with the Code designations. They are an exact specification. The code number AFAWK relates directly to the number of turns per pole, and hence you can calculate/compare motor speeds. Unfortunately, there's lots of interpretations of the translation between code numbers and motor speeds because people are so willing to publish their results.

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Bafang knows the codes the order takers may not. Maybe I was looking at the wrong spot but I never seen a document that I would trust is from Bafang that gives me definitive proof that turns is the code number. I think it maybe true but I would not trust my order from China on it. My 393 rpm motor has no code on it and that don't matter at all. The thing I needed was rpm. That and wheel diameter gives me the top speed. Maybe no one else calculates this but that is how I picked my motor.
The problem that we need to solve is how can we help first time BPM kit owners make informed decisions on this motor. They also want to know how it stacks up to other motors. Doing a search gives you lots of conflicting information , so at this point in time I can only give input on one motor and that isn't much help.

 

[spinningmagnets]

$130 for the full-sized Bafang-BPM http://www.greenbikekit.com/index.php/electric-motor/bldc-bpm-500w-36v.html

Also available from ES member Keywin / ecrazyman@gmail.com

Pics of opening up the smaller Bafang-SWHX http://endless-sphere.com/forums/viewtopic.php?f=2&t=9969

http://endless-sphere.com/forums/viewtopic.php?f=3&t=35323&start=100#p608467

Firstly, the two BPM models [from BMS-Battery] and the new CST cassette-hub model are all rated at 36V. The coding applies to a 36V input and all the values I will be giving you are in unloaded conditions. Let's begin with a code-16 motor and work our way to the code-8 motor.

Code_____RPM
16_______192
15_______205
14_______215
13_______230
12_______250
11_______280
10_______300
_9_______335
_8_______378. mind you, all of these specifications are directly from the engineers of Bafang.

 

[emiyata]

Firstly, the two BPM models [from BMS-Battery] and the new CST cassette-hub model are all rated at 36V. The coding applies to a 36V input and all the values I will be giving you are in unloaded conditions. Let's begin with a code-16 motor and work our way to the code-8 motor.

Code_____RPM
16_______192
15_______205
14_______215
13_______230
12_______250
11_______280
10_______300
_9_______335
_8_______378. mind you, all of these specifications are directly from the engineers of Bafang.

I seen this in the past when searching. Did Bafang post this on the web site? The strange thing about this document is engineers normally format the document and add things like speed tolerance +/- XX% Efficiency XX%. In no way I would say it is wrong but in no way I would take this as definitive proof. I still don't understand why they don't give the full spec. on the motors on a Bafangweb site.

Thanks for listing the information

 

[chas58]

Most people like to hear it in human readable terms, but if you like Engineer readable terms, this is probably what you are looking for: