eZee v Bafang Motor Performance Comparison

[Cyclezee]

I have just received some data that I thought I would share with the Forum.

Recently, I asked eZee if they could give me performace comparisons between the current eZee and a Suzhou Bafang/8Fun motor.

Below are the test results

	Bafang	eZee
@Maximum efficiency	80.54	83.44
Speed rpm	250	246
Torque Nm	10.11	26.3
@maximum output ~ 22amps
Efficency%	70.15	83.44
Torque Nm	26.5	26.3
Speed rpm	200	246

What you see here is a big difference in performance between eZee and Bafang motors, at given speed the torque output, and at the given torque the speed output.

There have been several upgrades and design changes to the eZee motor in the last year as they continue to develop the best hub motor in terms of performance, efficiency and reliability.

 

[amigafan2003]

So what is the "equivalent" Bafang motor? I'd have thought a BPM, rather than a little QWSXH or similar.

 

[NRG]

Whats the cost ratio? The efficiency of the eZee motor will be greater as its rotating faster than the Bafang. Agree, BPM may be a better comparison.

 

[Cyclezee]

Hi Amigafan,

The Bafang is the SWXH6 as fitted by many brands and the eZee motor is the EZ-3.

 

[Deleted member 4366]

That's very misleading, John. There's loads of different Bafang motors from low power to very high. Which one are you comparing?

Also, are there any Ezee bikes sold in the UK that run at 22 amps, which is the current at which the comparison is made?

 

[shemozzle999]

Is this the one John?

The lithium electric cars Bafang brushless high-speed the small motor the (8FUN SWXH motor) - Taobao

From the Germam pedelec site, for alternative more detailed specs:

http://www.pedelecforum.de/wiki/doku.php?id=e-motor:suzhou-bafang-swxh-hinterradmotor

 

[jackhandy]

Umm?

Not being over-endowed with smarts.....

Does this indicate that the bafang in my front wheel developes maximum torque at about 12 mph, whilst only being 70% efficient at those rpm?

 

[shemozzle999]

Powerful specs for the, fresh off the ship, EZ-3.
Shame it won't fit the Brommie but with figures like that it would probably rip the back end off anyway

 

[flecc]

The eZee motor with it's nominal 20 amp controller has always been a known powerful setup, but I must say I like those efficiency figures. Of course they always used to fit the Suzhou Bafang motors in all models, but some while ago decided they could do better.

 

[Deleted member 4366]

Umm?

Not being over-endowed with smarts.....

Does this indicate that the bafang in my front wheel developes maximum torque at about 12 mph, whilst only being 70% efficient at those rpm?

No. The test was done at much higher current than the Bafang was designed for. You'll get the 78% efficiency at 12mph.

 

[banbury frank]

Hi


36 volt Battery runs charged at 42 volts so 22 amp controller X 42 volts 924 Watts Motor 83 % efficient Approx 750 watts

It will pull well up hills

Frank

 

[Deleted member 4366]

You can calculate the actual power from the torque and rpm:
Ezee = 677.5w
Bafang = 555.0

22 amps seems a lot for the little Bafang. Ypu'd have to be careful not to over-heat it. I'm really surprided that it gives more torque than the Ezee at 22amps and 200 rpm (15mph). It doesn't sound right to me. Normally torque has fallen right off by that speed.