Bafang BBSO2, 750W mid-drive electric bike motor

Bafang is now selling a compact 750W mid-drive system that we think will become very popular, due to the large percentage of the population in US/Canada that wants a street-legal electric bike system.

A few years ago, the Bafang company could not help but to notice that mid-drives were becoming very popular in the European and Asian markets, and that Bosch and Panasonic had made long-term investments in compact and well-designed mid-drives that were integrated into the bottom-bracket (BB) of the bicycles frame. Many European and Asian markets are in power-limited countries, such as the 250W limit in the EU and Australia.

It is easy to de-rate a larger motor by limiting the max amps (also allowing it to run cooler than normal), but it can be problematic to up-rate a smaller motor. Also, the Bosch and Panasonic units require a frame that is specifically made to fit the drive, so these Bosch and Panasonic drives cannot be retro-fitted onto common bicycle frames. For both of these reasons, I am very excited about the potential of the new Bafang BBS02.

I could not help but to take notice when the 350W Bafang BBS01 was introduced. The thing that really caught my attention was that the Bafang unit could be fitted to almost any bicycle frame. I do feel that the 350W unit is too weak for an off-road bike of any type (in my humble opinion), but there are no power restrictions for off-road electric bikes.

Because of the 750W power limit in the USA (along with the 500W power limit in the Canada)…the 350W  BB-S01 seemed to be a good idea that was also a “missed opportunity“. Its true that it was first marketed in Europe and Asia where that power level was appropriate, but with just a little extra effort, they could have the best possible product for the growing interest in street-legal E-bikes in North America.

As it turns out, my concerns were for no reason. The BBS01 was so popular in their initial marketing push, that the factories were maxed out just keeping up with the 350W unit demand. Their production capability was ramped up recently to meet the unexpectedly high demand, and Bafang revealed at the Interbike September 2013 meet in Las Vegas that they have a 750W version which is just now beginning to arrive in North America (the first 750W prototypes were shown in the Shanghai show in May 2013 to gauge industry interest).

Here’s a close-up of a 750W unit attached to an Electra Townie step-through frame.

The 750W unit appeared to be the same physical size as the 350W unit, and my experience with exaggerated China-made performance claims made me skeptical of the 750W spec. However, I have recently been informed by a North American distributor that the motor is wound to a different Kv, so when it is run at 48V, it will spin at the same output RPMs as the 36V / 350W version.

This allows the mechanical-gear RPM-reduction to remain the same for both units, and they can also share many of the same housing and interface parts. More volts can add more power without significantly adding more heat, and it is the heat that has frequently proven to be the limiting factor on these smaller motors.

However, we do not live by volts alone. The North American distributor has verified that the stator on the 750W unit is 5mm wider, which allows for a slightly greater copper mass (it is roughly one pound heavier due to the wider steel stator and extra copper wire in the coils). This means that the BBS02 motor can handle more amps than the BBS01 motor before reaching saturation. As you can imagine, I was very pleased to learn this. Both units have built-in over-temperature protection circuits that will cut power before the unit would be damaged.

As you can see, this is a production unit, not a prototype. 48V X 20A is 960W, so the factory is optimistic about this model (even though it’s labeled the “500W”). However, if you are riding on a long uphill while drawing max amps…the over-heat protection circuit may cut the power just when you need it most. Since your hills may be steeper than my hills, start out with the amps being limited, and then slowly raise the max amps until heat becomes an issue (edit: of course, this is only if you are using an external controller, the stock controller is not adjustable).

In the picture shown, the “1307090018″ number on the motor housing means:

130709 = 13 (2013), 07 (July, 7th month), 09 (9th day)

0018= Serial number, this is the 18th unit produced that is a BBS02-48V-500W

In the picture shown, the “1307090018″ number on the motor housing means:

130709 = 13 (2013), 07 (July, 7th month), 09 (9th day)

0018= Serial number, this is the 18th unit produced that is a BBS02-48V-500W

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The “JSCF0034.0″ and “13070012″ refers to the controller.

I do not yet understand the JSCF designation, but the 13070012 seems to mean that this controller was manufactured in 2013, 7th month, serial number 12. So far, there are seven stock controller/stator combination options:

250W = 24V X 18A

250W = 36V X 15A 

350W = 36V X 18A

500W = 36V X 25A 

350W = 48V X 15A (BMS-Battery)

500W = 48V X 20A

750W = 48V X 25A (trusted vendor of the year em3ev.com), (lectriccycles.com) or also (EMPowered cycles)

EDIT: go to the bottom of the article to read about the change in the controllers in the spring of 2014

All versions can be bought direct from China through Alibaba or Aliexpress, but if you want to try that…let the buyer beware!

Written by Ron/Spinningmagnets,2013