Bafang BPM motor data

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Jeremy Harris
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Bafang BPM motor data

Post by Jeremy Harris » Sat Aug 25, 2012 6:20 am

Like others, I suspect, I've struggled to find good data on the true Kv (RPM/V) for the BPM motor. The vendors seem to advertise confusing, meaningless or just plain wrong data, expressed as "RPM at 36V", often without saying whether this is no load or loaded. I did manage to find a table from Suzhou Bafang that gives data for some motor winds (code numbers) and I have used this to derive estimated Kv values for the codes that we don't have data for, using a derived motor constant based on a linear interpolation.

Bafang quote an RPM tolerance on their data, and I've repeated that here, with an estimate of the RPM tolerance they might use for each. This gives a maximum and minimum RPM tolerance either side of the nominal value for a given voltage that could expected due to manufacturing tolerances.

The RPM for any voltage and motor wind can be estimated from the data below by just multiplying the value of Kv for a particular motor by the battery voltage. For example, a Code 13 motor running on 49 V could have a no load speed of anywhere between 314 and 338 rpm, with an average motor being around 326 rpm at this voltage.
Bafang BPM data.jpg
Bafang BPM data.jpg (144.13 KiB) Viewed 3321 times
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John in CR
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Re: Bafang BPM motor data

Post by John in CR » Sun Aug 26, 2012 12:35 pm

Nice info Jeremy. I really like the idea of an 11rpm/volt geared hubbie as the starting point for a motor hack. Have you popped the cover on yours? I'd love to get the stator dimensions, lamination thickness, the approximate gauge of the winding bundle, and the physical gear reduction for a BPM.

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jateureka
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Re: Bafang BPM motor data

Post by jateureka » Mon Dec 09, 2013 3:37 pm

Spinningmagnets has done a complete listing of BPM resources, tear down, spec's, etc in the Tech Ref section here https://endless-sphere.com/forums/viewto ... 16&t=51237
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