Bafang Bpm, how many RPM?

[gartmu]

msbattery answer me this:
48V 500w rpm393, Front. code 11.
48V 500w rpm393, rear, code 10 .
Gartmu, is your motor front or rear?

My motor is front. The code 10 is about 30rpm faster than code 11 so it should have a no load speed of about 420rpm not 393rpm. Just remember when increasing speed you also decrease torque in the same proportion.

[itselectric]

Gartmu:
Can u tell us what is marking on the motor? 26(11), 20(9), 20(8), etc..

The marking is 16(11).

gartmu:
I have never seen a 16(11) Bafang motor. Was it a typo 26(11)?
Ken

[gartmu]

I have never seen a 16(11) Bafang motor. Was it a typo 26(11)?

Yes, it´s a 16(11), here´s a picture.

8FUN BPM 48V500W 16(11)

BPM.jpg (155.02 KiB) Viewed 972 times

[itselectric]

I have never seen a 16(11) Bafang motor. Was it a typo 26(11)?

Yes, it´s a 16(11), here´s a picture.

BPM.jpg

gartmu:
thank you so much for sharing the picture! So i guess the wattage may somewhat depends on wheel size or the first 2 number code.

[gartmu]

So i guess the wattage may somewhat depends on wheel size or the first 2 number code.

The wattage of the motor is always 500W. The 16(11) means that a code 11 motor in a 16" wheel will result in a max speed of about 25Km/h, the max limit in europe. Of course if you mount that motor in a 26" wheel it will give more than 45Km/h.

[motomech]

This is what freaks me out a little about BMS battery.
You can get both the 36v and 48v versions in 393rpm.

Now given the rated volts @ 36v and 48v this would mean that the 36v version should be a different wind to the the 48v to enable the same rpm.

Can anyone claify this?

Yeah, it's confusing as hell.
I've been trying to get my head around this for a while now and I think your observation that,

Quote-"Now given the rated volts @ 36v and 48v this would mean that the 36v version should be a different wind to the the 48v to enable the same rpm."

Is the key to understanding what BPM winds BMS Battery actually offers, at least the higher rpm winds.

Here is what I think I know,

Based on what Rizo said,

Quote "...bmsbattery answer me this:
48V 500w rpm393, Front. code 11.
48V 500w rpm393, rear, code 10 ...."

Bms Battery only offers three BPM high-speed winds, there are,

The 48V, rear mount w/ a no-load rpm listed as 393, is a Code 10[310 rpm @ 36v].

The 48v Frt. mount w/ a no-load rpm listed as 393, is a Code 11[285 rpm @ 36V].

And according to jateureka,

Quote-"I ordered the 36V 350W front BPM motor in a 201 rpm winding from BMS Battery and received a 26 (13) motor."

So is't possible that,

The 36V frt. or rear mount w/ a no-load rpm listed as 393, is a Code 13[225{my est.}rpm @ 36V].

Has anyone recieved a 36V[393 rpm]rear and can confirm that it is a Code 13? The Ebike CA sim. indicates that it is closer to a Code 11 or Code 12.

These codes seem to jive with the top speeds for BPM faster winds that I have noted here in ES.

Concerning the slower winds, I'm still rather perplexed. Both Gartmu and d8veh have indicated that the 201 rpm winds produce Euro-legal speeds of 20 KpH @ 36V, so I will assume that,

Both the frt. and rear 48V slow-winds motors are Code 8's[201 rpm @ 36V].

But where does that leave the 36V slow winds? Could they be the same as the 48's[V]?

Code 8's?

Anyone want to comment on this remarkably obtuse system[perhaps a plot to make us mind-dead?]. I hope I haven't muddied the waters even more.

[miuan]

motomech: I'm afraid you've got it all the other way round. Reality is, the lower the code number, the higher the speed. Actually, I'm pretty confident to say the code means number of copper turns, so assuming similar motor size to the MACs, the code 10 will be as fast as the 10 turn MAC etc. In my applications this has proven correct as I own and ride both of these motors.

More on the topic can be seen here:
viewtopic.php?f=3&t=12582
The numbers don't exactly copy what BMSBattery indicates, but it's in the ballpark.

When purchasing from BMSBattery:
393 @ 36V = code 8
393 @ 48V = code 10 (mine does 40mph in 700c rim for short periods at 74V)
201 @ 36V = code 13 (a friend of mine runs it at 74V and 26in, does about 30mph)
201 @ 48V = code 17? (I've ordered this one for my dad, will be able to confirm soon)

I know BMSBattery could do a better explanation of different wind speeds, but most should get it easily. Hell, one year ago, they had no speeds indicated online, and I had to spend almost an hour to see which code designation is in stock. So it's a huge step forward (for the chinese fwiw).

[casainho]

I bought recently the 48V500W 393rpm from bmsbattery, the motor manufacturer data is November 2011, with the KU123 controler. It gives 43Km/h in flat and climbs at more than 30Km/h in 6% hills. The spoke lenght for 26" rim is 210mm, you need to use 13G spokes, at first I used 14G spokes but every 1000Km one spoke broke. 14G spokes are not recommended by the manufacturer.

Gartmu, thanks for sharing!! I am looking to buy the same motor and is great to see all the info you shared here, thanks

One question: you alredy told you get the 43km/h in flat without pedaling. Could you please tell us what is the speed if you pedal at moderate force? and what is the speed with the wheel on the air (maximum speed of the motor)?

My actual electric bicycle is this one (V2.1 in Portuguese):


It is a Cute-85 motor for 16'' but installed on a 26'' wheel, 250W, 24V. Battery 24V 25Ah. I do 60km (30km go and more 30km to return) in one charge, 2 times a week. Now, I think in changing for the Bafang 500W 48V and battery 48V 10A... I would like to have more speed... top speed with Cute-85 is about 35km/h on flat and with me pedaling at moderate speed.

Medium speed of about 30km/h on my travel of 30km + 30km (V2.0 in Portuguese)


But I started with a 24V 180W motor and 24V 10A battery (V1.0 in Portuguese):


The components for V2 were all bought on BMS Battery. The battery for V1 were bought on BMS Battery.

[d8veh]

BMSBattery only do 201 RPM or 393 RPM. The 393 RPM won't be very efficient as it's meant for small wheels. You'll waste a lot of battery, which will compromise your range. Your best bet is to use a 36v 201 RPM at 48v, which will give about 35 kph and very good climbing power. Only use the 393 RPM if your journey is flat. Other suppliers do the other versions of the motor. I would say the one you want is code 11 or 12. You might be able to get one from Cell-man. I know EVassemble were doing them, but you have to get your own rim and spokes.

[cwah]

D8veh, so the best bet is low RPM and very high voltage in order to have optimal range?

I mean it's better to have a BPM 201RPM at 74V rather than a BPM 393RPM at 36V, if they both reach the same max speed?

[jbond]

Another data point. I have a BPM marked 36v350w 26(11) which I take to be a code 11 designed for a 26" wheel. I've measured a no-load speed of 23.5mph (cycle computer calibrated against GPS). Typical flat out top speed is about ~20mph. Working all that back gives a no load rpm of 308 on a nominal 36v freshly charged Li-NiCoMn 10s battery.

The BPM was supplied with an Alien Aurora bike. The controller appears to be a Bafang one with a multi-wire to a wiring concentrator and 3 speed control at the front of the bike. The figures above are in "high speed" mode.

See also this old post that details BPM specs.
http://endless-sphere.com/forums/viewto ... =3&t=12582

[d8veh]

D8veh, so the best bet is low RPM and very high voltage in order to have optimal range?

I mean it's better to have a BPM 201RPM at 74V rather than a BPM 393RPM at 36V, if they both reach the same max speed?

The most important thing is to match the motor to your normal speed that you expect to be going. It can make a significant difference to your range if you have a mismatch. When a 393rpm motor is laboring up a steep hill at 200 rpm, efficiency could be as low as 60% compared with the maximum of 78%, while as a 201rpm motor would be achieving the 78%, but you only get half the top speed.
@Jbond. That sounds about right, so a 201 rpm would achieve about 2/3 of 24 mph, which is 16mph at 36v and about 22mph at 48v. Mine's about 1mph up on that.

[motomech]

BMSBattery only do 201 RPM or 393 RPM. The 393 RPM won't be very efficient as it's meant for small wheels. You'll waste a lot of battery, which will compromise your range. Your best bet is to use a 36v 201 RPM at 48v, which will give about 35 kph and very good climbing power. Only use the 393 RPM if your journey is flat. Other suppliers do the other versions of the motor. I would say the one you want is code 11 or 12. You might be able to get one from Cell-man. I know EVassemble were doing them, but you have to get your own rim and spokes.

I'm glad you dropped in, as I've read all your posts at PedElecs.
In your review of BPM/Giant[rear wheel mount], you said,

QUOTE "...from BMSbattery in China. The kit comprises 350w motor (code 12) in wheel, 350w 9 FET controller, throttle, pedal sensor and brakes with switches."

But above you seem to indicate that this wind is not available from BMS Battery. Also[above, in different post], Miuan states,

QUOTE "When purchasing from BMSBattery:
393 @ 36V = code 8
393 @ 48V = code 10"

While Gartmu said

Quote "msbattery answer me this:
48V 500w rpm393, Front. code 11.
48V 500w rpm393, rear, code 10 ."

I really hate to belabor this, but I'm still unclear as to what winds are available from BMS Battery.
Can you shed any more light on this?

Thanx,
Signed Confused

P.S. Also, during your review of the BPM 12 you stated that you were unable to make a top speed run[speed limited]. Have you since been able to make one?

[Scottyf]

When myself and D8veh brought our bpm's from bmsbattery you could specify a wind to your requirement. It was slower to get the motors but you had what you wanted.
Now they only do 4 winds and that's it. Either a high speed or high torque. No inbetween winds.

I also have the code 12 @ 36v which is intended for 20mph in a 24inch wheel. A mid wind. But I laced it in a 700c wheel.

You definetly have less of a choice at the moment. There also seriously more expensive than they used to be. You could get a full kit delivered to the uk for £150 or $225

[motomech]

Gee, and here I thought the Chinese were industrious

Thanx for the explanation Scott.

[Scottyf]

If you contact bafang directly you can get what ever you like. But it will cost a little more than bmsbattery.
It's worth noting. They do single orders but it's obviously expensive and they will only supply the motor. Not laced etc.

[miuan]

The most important thing is to match the motor to your normal speed that you expect to be going. It can make a significant difference to your range if you have a mismatch. When a 393rpm motor is laboring up a steep hill at 200 rpm, efficiency could be as low as 60% compared with the maximum of 78%, while as a 201rpm motor would be achieving the 78%, but you only get half the top speed.

You do get half speed with slow wind, but DO NOT get 60% efficiency with fast one while the slow is doing 78. The difference can be couple per cent, not more. I go as far as assuming you get even more losses in the controller/wiring than the difference in motor efficiency, if you decide to use same voltages on both systems. Simply because you need to half the voltage and double the current with the fast motor, while just passing all the voltage to the motor with the slow one.

[motomech]

Yes, but at that point, it would seem to make more sense to buy a Mac from Cell_man.
The reason to buy from BMS Batt., at least for me, is get some other stuff[like a bulk charger, or two kits]and consolidate on the shipping.

[motomech]

The most important thing is to match the motor to your normal speed that you expect to be going. It can make a significant difference to your range if you have a mismatch. When a 393rpm motor is laboring up a steep hill at 200 rpm, efficiency could be as low as 60% compared with the maximum of 78%, while as a 201rpm motor would be achieving the 78%, but you only get half the top speed.

You do get half speed with slow wind, but DO NOT get 60% efficiency with fast one while the slow is doing 78. The difference can be couple per cent, not more. I go as far as assuming you get even more losses in the controller/wiring than the difference in motor efficiency, if you decide to use same voltages on both systems. Simply because you need to half the voltage and double the current with the fast motor, while just passing all the voltage to the motor with the slow one.

Yes, the Sim. at Ebike CA would seem to bear that out. I see losses in the low single digit range[comparing, for example, the BMC fast and slow winds].
There has been a solid argument here that the highest system efficiency is attained by over-volting a slow wind motor.
By as Dogman[and others]have pointed out, the differences are over-shadowed by things like, what jacket are you wearing or what tires[and pressure]are you running.
I'm thinking that, except for a hyper-miler, system efficiency should be way down on the list of factors to consider.

[d8veh]

I'm glad you dropped in, as I've read all your posts at PedElecs.
In your review of BPM/Giant[rear wheel mount], you said,

QUOTE "...from BMSbattery in China. The kit comprises 350w motor (code 12) in wheel, 350w 9 FET controller, throttle, pedal sensor and brakes with switches."

But above you seem to indicate that this wind is not available from BMS Battery. Also[above, in different post], Miuan states,

QUOTE "When purchasing from BMSBattery:
393 @ 36V = code 8
393 @ 48V = code 10"

While Gartmu said

Quote "msbattery answer me this:
48V 500w rpm393, Front. code 11.
48V 500w rpm393, rear, code 10 ."

I really hate to belabor this, but I'm still unclear as to what winds are available from BMS Battery.
Can you shed any more light on this?

P.S. Also, during your review of the BPM 12 you stated that you were unable to make a top speed run[speed limited]. Have you since been able to make one?

Scotty's explained it pretty well. I wouldn't take too much notice of the rpm stated by BMSBattery: Go by the code number and the RPMs stated in Wurly's post at the beginning of this thread. When you run a code 11 at 48v, you get 33% more RPM than the same motor at 36v. I'm not sure whether there is any difference internally between a 48v and 36v motor. Perhaps somebody here knows. We believe that the code number corresponds with the number of turns of wire round the poles, which has a direct bearing on speed and so does the voltage.

[d8veh]

The most important thing is to match the motor to your normal speed that you expect to be going. It can make a significant difference to your range if you have a mismatch. When a 393rpm motor is laboring up a steep hill at 200 rpm, efficiency could be as low as 60% compared with the maximum of 78%, while as a 201rpm motor would be achieving the 78%, but you only get half the top speed.

You do get half speed with slow wind, but DO NOT get 60% efficiency with fast one while the slow is doing 78. The difference can be couple per cent, not more. I go as far as assuming you get even more losses in the controller/wiring than the difference in motor efficiency, if you decide to use same voltages on both systems. Simply because you need to half the voltage and double the current with the fast motor, while just passing all the voltage to the motor with the slow one.

Have a look at the Ebikes.ca simulator. Choose the Ezee motor as the nearest equivalent. Top speed at 36v is 30kph with efficiency of 78%. On a 10% incline, it slows to 15kph with an efficiency of 64%. That means that your wasting 18% more.

[miuan]

Have a look at the Ebikes.ca simulator. Choose the Ezee motor as the nearest equivalent. Top speed at 36v is 30kph with efficiency of 78%. On a 10% incline, it slows to 15kph with an efficiency of 64%. That means that your wasting 18% more.

You are wasting 18% more efficiency on the uphills because you require MORE power at LOWER rpm!
If you ask the same power of a slower motor at the SAME speed up the same hill, you will still bog it down in a similar way.
If you are more interested in this topic, check out my recent thread, especially what Alan B posted.
When using the simulator, choose BPM500W, it's a 10 turn wind afaik.
viewtopic.php?f=2&t=35359

[casainho]

I just bought from BMSBattery the Bafang 48V500W BPM Front Driving Hub Motor 393 RPM. While I live on a relative flat place and the 393 RPM should do 47km/h at maximum and maximum Efficiency is on that velocity, I guess. But I will not be able to run always at 47km/h!! There are places, even if flat, I will need to go at 20km/h or even less due to obstacles. My question is: if I put the throttle at 50%, the RPM should be 393/2, right? so the velocity will be 23.5km/h and the Efficiency of the motor will be the maximum at that velocity?

I am using right now a Cute-85 250W 24V motor for 16'' but installed on a 26'' wheel (see my post here). I will change for the Bafang 48V500W BPM 393 RPM soon as it arrives:


Example of my riding (pictures from my Android My Tracks software):

[miuan]

Yes that's right. Efficiency is always good if you don't load the motor too much. So on flat road, it should always be about 77-82% depending on speed. It only drops when you want more power (acceleration, ascents).

[d8veh]

Nice bike. I think you'll find that the BPM motor will make your journey a lot more enjoyable. Let us know how you get on.