Bafang bpm & cst motors - what variations are available?

[jackhandy]

Quite a few of the bikes coming to the Eden ebike event, on 20-24th april, have the bpm or cst motor fitted: It appears that this motor is one of the main contenders in the Hub vs Crank tussle presently being fought out, with the Bosch Centredrive being t'other.

I, for one, am totally confused as to the true identity (multiple or otherwise) of these motors:

I read of 250/350w: 350w restricted to 250w: 350/500w: 500w.......

Could someone, with a good working knowledge of them, please enlighten me as to what is actually available from the manufacturer, what is being fitted to bikes which are en15194 compliant &, most of all, which can be upgraded once the warranty's out, by use of a bigger controller? The max practical amperage sustainable would be appreciated.

I'm sure this has all been provided before, but everywhere I look seems to confuse me more

Feel free to post links if it'll save typing!

 

[banbury frank]

Hi We Have our Own CST Motor NOT made by Bafang We call it the Commuter Baby With a UK legal controller it is 250 watts 15 mph BUT as all our kits it runs on 48 volts so will Climb Hills like a mountain goat It will be available with a switchable controller Between 25 KPH and 45 KPH And 500 to 1,000 watts Not Cheap BUT High power Battery's with A 50Amp Battery Management are Expensive Available in 10AH and 15 AH and 20AH Weight off Motor 3.5 Kilos

PS EN15194 is nothing to do with motor it is the specification for a finished electric bike

Frank

 

[Deleted member 4366]

This is how I see it. Some is supposition. but I don't think I'm far from the truth:
For both 36v motors, there's two versions: 350w and 500w. The 350w versions give full power at about 25 amps and perform happily at 22 amps, and the 500w ones give full power at 40 amps or more, and 30 amps is the normal current to run them at.

For comparison, 250w Bafang SWX motors are usually run at about 14 amps.

Some electric bike makers wanted more torque than what the SWX motor produced, and they figured out that the 350w motors were about righ, but the 350w label would be a bit of an embarrassment, so Bafang produced some with 250w labels on.

The rating of the motor is fairly meaningless. It shows the power that it's capable of being run at continuously. How much power you get from it is dependent on what speed you let it go to and how much current you let it have. Like Fank says, the EN15194 certificate applies to the bike, not the motor.

On a crank-drive motor, it's the power of the motor affects how you go up hills, but for a hub-motor, torque is the key characteristic. The bigger motors give more torque.

How you rate the power is not very clearly defined, so some people are using a bit of poetic licence when they define what it is for their system. As long as they get a EN15194 certificate, nobody needs to worry about how or why - just enjoy the extra that you get with these motors.

The Manufacturers of crank-drives have done the same thing. Bosch started it when there was a step-change in power from the old 26v Panasonics that were also rated at 250w. It's not so easy for the crank-drives to push the power further because the power transmission system can't handle it reliably

 

[jackhandy]

Thanks for that d8veh:

So, presumably, it's actually the 350w motor which is on all the bikes with a 15194 certificate.

Therefore, the controller & its programming is what makes the difference, along with the strength of the battery.

I'm now in a position to do some comparative testing on the Eden track - I think

 

[103Alex1]

Thanks for that d8veh:

So, presumably, it's actually the 350w motor which is on all the bikes with a 15194 certificate.

Therefore, the controller & its programming is what makes the difference, along with the strength of the battery.

I'm now in a position to do some comparative testing on the Eden track - I think

I think the only real difference between the 350W and the 500W is effectively the torque - the latter having a bit more capacity to deliver "grunt" up the hills with the right controller and battery voltage than the former (as opposed to being capable of any kind of higher speed if derestricted), everything else equal - but might be wrong on that.

Be very interested to hear how the bikes with CST motors perform if you're above to get any of them up seriously steep slopes anywhere. There should be places nearby round there even if the official track isn't long and steep enough for a proper going over !

 

[Kudoscycles]

This is how I see it. Some is supposition. but I don't think I'm far from the truth:
For both 36v motors, there's two versions: 350w and 500w. The 350w versions give full power at about 25 amps and perform happily at 22 amps, and the 500w ones give full power at 40 amps or more, and 30 amps is the normal current to run them at.

For comparison, 250w Bafang SWX motors are usually run at about 14 amps.

Some electric bike makers wanted more torque than what the SWX motor produced, and they figured out that the 350w motors were about righ, but the 350w label would be a bit of an embarrassment, so Bafang produced some with 250w labels on.

The rating of the motor is fairly meaningless. It shows the power that it's capable of being run at continuously. How much power you get from it is dependent on what speed you let it go to and how much current you let it have. Like Fank says, the EN15194 certificate applies to the bike, not the motor.

On a crank-drive motor, it's the power of the motor affects how you go up hills, but for a hub-motor, torque is the key characteristic. The bigger motors give more torque.

How you rate the power is not very clearly defined, so some people are using a bit of poetic licence when they define what it is for their system. As long as they get a EN15194 certificate, nobody needs to worry about how or why - just enjoy the extra that you get with these motors.

The Manufacturers of crank-drives have done the same thing. Bosch started it when there was a step-change in power from the old 26v Panasonics that were also rated at 250w. It's not so easy for the crank-drives to push the power further because the power transmission system can't handle it reliably

Dave,as usual I learn a lot from your postings. Just to point out that the motor can be rated as EN15194 as well as the complete bike. I have seen individual certificates for various motors that assures that particular motor is EN15194 compliant. I think that having the motor certified takes that element out of the overal bike testing procedure...certainly the 8-fun,BPM and TCM (crank drive)motors I have seen individual certificates for those motors.

 

[Marctwo]

I could issue a certificate to say my phone is EN15194 compliant... but that wouldn't mean it is.

EN15194 is about compliance not certification.

 

[Deleted member 4366]

EN15194 lays down some requirements for the motor, mainly by referring to other standards. You could still certify that the motor meets the requirements of EN15194.
The main thing we were discussing was the power requirements. EN15194 refers to a method of testing the maximum power rating of the motor, based on stable temperature. If you run your motor at a lower power, it'll pass, because the requirement is that the temperature should be stable. It comes back to the rating of the motor. Up to the point that the temperature rises beyond the safe limit, the manufacturer can rate it at anything they want. The test was designed to stop manufacturers claiming that their motors were more powerful than they were, not the other way round.

 

[Marctwo]

EN15194 lays down some requirements for the motor, mainly by referring to other standards. You could still certify that the motor meets the requirements of EN15194.

Hmm... after power I can't find anything else relevant to motors except maybe annex C. Is it possible any suitable motor could fail to meet the EM spec's?

 

[shemozzle999]

Hi Jackhandy

The power rating of motors which you focus on is just a small part of EN15194, it's main purpose is to provide a safe minimum standard requirement for manufacturers to produce to, effectively to ensure a safe and reliable product for the user.

http://www.vae-enov.com/fiches_2010/norme_en_15194.pdf

 

[Deleted member 4366]

Hmm... after power I can't find anything else relevant to motors except maybe annex C. Is it possible any suitable motor could fail to meet the EM spec's?

EN15194 requirements that applies to the motor on its own.

4.2.3.1 Connector temperature
4.2.3.3 Wiring
4.2.3.5 Connector type
4.2.3.6 Moisture resistance
4.2.7 Max power
C 1.1 Marking
C 1.2.1 Function
C 1.2.5.2 Broad band radiation
C 1.2.6.2 Narrow band radiation

If you look at the bit about power, you can see that if you rated it at 250w, you run it at that power, and if it doesn't get too hot, it passes.

 

[jackhandy]

Hi Jackhandy



http://www.vae-enov.com/fiches_2010/norme_en_15194.pdf

Gee, thanks Schemozzle - I think:

I've gone all glassy-eyed just reading the index!

I'll have a read next time I have a sleepless night - Should do the trick

 

[shemozzle999]

Gee, thanks Schemozzle - I think:

I've gone all glassy-eyed just reading the index!

I'll have a read next time I have a sleepless night - Should do the trick

I hope you do.

You will see that it is about the entire ebike construction and not just about the the power.

If you want to pursue down the road of allowing more power then I hope you do not have sleepless nights worrying about the 14 year lightweight person that would be allowed to ride such a machine.

Perhaps d8veh could persuade his head to allow him to demo his machine to the school kids - it might start a new craze and increase sales!

Not to mention all the media attention it would generate.

 

[Marctwo]

EN15194 requirements that applies to the motor on its own.

4.2.3.1 Connector temperature
4.2.3.3 Wiring
4.2.3.5 Connector type
4.2.3.6 Moisture resistance
4.2.7 Max power
C 1.1 Marking
C 1.2.1 Function
C 1.2.5.2 Broad band radiation
C 1.2.6.2 Narrow band radiation

If you look at the bit about power, you can see that if you rated it at 250w, you run it at that power, and if it doesn't get too hot, it passes.

Cheers Dave,

I was actually thinking of requirements that wouldn't necessarily be met for the motor to be fit for sale in the first place. lol. But that's not what I asked... my bad.

 

[Beach Thorncombe]

Quite a few of the bikes coming to the Eden ebike event, on 20-24th april, have the bpm or cst motor fitted: It appears that this motor is one of the main contenders in the Hub vs Crank tussle presently being fought out, with the Bosch Centredrive being t'other.

I, for one, am totally confused as to the true identity (multiple or otherwise) of these motors:

I read of 250/350w: 350w restricted to 250w: 350/500w: 500w.......

Could someone, with a good working knowledge of them, please enlighten me as to what is actually available from the manufacturer, what is being fitted to bikes which are en15194 compliant &, most of all, which can be upgraded once the warranty's out, by use of a bigger controller? The max practical amperage sustainable would be appreciated.

I'm sure this has all been provided before, but everywhere I look seems to confuse me more

Feel free to post links if it'll save typing!

See?

THIS is what frustrates me about the Pedelec forum.

Someone asks a straightforward question, (it really is) ... and they get paragraph after paragraph and post after post of, I'd claim, irrelevant technical asides that do little to either answer the original question OR enlighten anybody NOT in the little 'techy club' on here.

And yes. Of course the tech info isn't really irrelevant and, of course, we worship the 'site experts' who freely give us their time and wisdom ...

But, Jeez, can we, for once, have a reasonably straight answer to a reasonably worthy, straight question?

I found this old thread because I was seeking an answer to a question of my own ... related (and similar to) the Bafang BPM motor question Jack appears to be asking.

So let me ask my question. (Similar to Jacks), but let us see if someone can give me a straight answer.

Here goes.

I'm a potential customer.

I want to BUY a brand new 700c front wheel ... with a Bafang BPM hub motor therein.... along with a beefy, suitably appropriate, controller to cope with the torque this motor dishes out.

Apparently, (as Woosh recently commented elsewhere), the Bafang BPM hub motor is seriously fierce, (my words), and, presumably, a fantastic motor to consider if anyone is, (like me), keen to enhance their existing hill climbing machine.

So ... without all the BS, (and without quoting EN15194 yet again), IN PLAIN ENGLISH, please provide a link or a simple answer regarding what I should be attempting to buy to, absolutely, make the correct choice of Bafang BPM hub motor / 700c wheel assembly and controller.

If you think you may need to pick me up for not, apparently, asking the right question or if you feel an equally frustrating need to simply show off just what a fabulous clever clogs you are ... well ... well done you ... but I just don't care for more technical distraction.

If, however, you can recognise that I am an actual customer, (to someone), with money burning in my pocket just waiting to be placed on an order for a 700c Bafang BPM front hub wheel assembly with appropriate controller and lower RPM for greater torque ... then ... Please help.

So ... in the plainest, plainest ... plainest language I can muster,

"I'd be eternally grateful to the Gods if someone could recommend the correct Bafang BPM, (or genuine equivalent model), hub motor / 700c wheel / controller etc to turn my lightweight alloy Xbike framed home built beach machine into the hairiest, bad tempered, beast of a mountain goat the UK has ever seen.".

WHAT legal product should I be asking for? (It'll be on a 36v system and intended to be legit and legal).

---

And, just for fun, if I said I was planning to build a 15ah (or greater) 48v (or greater) lithium cell pack and illegally create a 1000W Frankenstein of a machine, (purely for off road hill climbing cliff and coastal pursuits), again ... without all the Watts = Volts X Amps distractions ... please just recommend some 'off the shelf' consumer parts I might buy right now.

Thanks.

(You know I love you really) XXX

 

[Deleted member 4366]

You can fit any motor that's stamped, marked or catalogued as 250w to be legal. Most BPMs are marked 350w or 500w.

It's difficult to make things simple when they're not. that first bit is, so no problem there, but when you come to torque and speed it gets complicated.

Most BPMs are marked with a speed code:

The number in brackets is the speed code (very important). The number next to it is the wheel size (not important). In a 700c wheel a code 15 will give you about 18 mph (201 rpm). A higher code number is slower (code 16 about 180 rpm) and a lower code number is higher speed. When you mention these code numbers to suppliers, they don't have a clue about them, nor much else about the speed. Low speed means high torque.

48v will give 30% more torque than a 36v one.

There's 500w and 350w (250w is same as 250w) ones. The 500w ones can handle 30 amps at 36v or 25 amps at 48v. The 350w ones can handle 22 amps at either voltage.

These motors give massive torque. You need strong steel forks to put anything more than a low power one on the front. Even then, you won't get much traction, especially on the beach. You need a rear drive system, or better still 2WD with a front and rear motor, in which case a pair of normal 250w hub-motors running at 36v and 15amps each will be perfect.

The power for all motors comes from the controller: More amps = more torque. More volts = more speed.

Now comes the simple answer: If you want a beach cruiser , forget about the BPM motor, get two normal hub-motors, a 36v battery greater than 15Ah and capable of 30 amps continuous, two 15 amp controllers of which one should be with LCD and the other just a plain throttle one, a throttle and a PAS. If you get it, I'll show you how to wire it up.

Do I get "well done" for that.

 

[D8ve]

D8veh

Anyone who whines after that reply deserves a stiff ignoring.

Pat on head.

 

[tongxinpete]

I went down the twin 15A (peak) motor route as an experiment, worked absolutely great. Actually It was 15A Q100 201 rpm laced into a 24'' rear wheel rim for added torque. I had an 11A Tongxin in the front. Sadly the different controller types & the fact that each motor ran off totally different batteries meant that each had to have a separate throttle. I only broke it up when my stepson needed the Tongxin to run a bike to get to a new job. The hill climbing was awesome - massive help climbing out of the Ironbridge Gorge.
Only lack of money meant I could not run the twin identical controllers from a single throttle (ideal if poss) Either one of the motors powered up singly, once up to speed could only draw about 5A on the flat. The 24'' wheel just made the ATB saddle one inch closer to the ground.
I had to make a plate to carry the rim brake in its new position. Had I had disc brakes then the 24'' rim would not have been even this problem. top speed of the Q100 in 24'' rim = 15.5 mph.
I can see the added benefit of the 2 wheel drive on soft ground, otherwise could a Q128H be a candidate? Beware that Bmsbatteries send out BPM hubs totally at random. Greenbikit sometimes do quote the bracketed code,
There is a guy in HK who sends the code 15 & 16 but he is a bit costly.

 

[Beach Thorncombe]

Excellent post, D8veh. Thank you.

I had come across the RPM thing while researching the BPM product and, primarily, am drawn to the hill climbing characteristics of a lower RPM / higher torque arrangement so thank you for the coding info and other details.

Furnished with your information, I'm planning to purchase a BPM in the next 7 days and plan to own one as a 'pool' hub motor to share between machines. (This will let me experiment using a BPM hub drive with several machines to test the hill climbing characteristics over different ebikes).

I've standardised all my ebike battery, controller and hub / mid drive motor connections to allow me to switch and swop my ebike power related resources in a 'plug and play' fashion but, with three 26" wheeled machines and two 700c wheeled machines, I have to bite the bullet and make a choice regarding going for a 26" BPM or a 700c one.

I'm tempted to choose a 26" BPM hub, (to suit three machines), though realise I'm going to have to make myself a portable style brushless controller type loom to accomodate the BPM brushless controller.

My modded Powabyke Xbyke normally accomodates a motorised 700c front wheel but, as I've done in the past, I can run it with a motorised 26" wheel so even the Xbyke, (my lightest machine), should get a chance to experience the BPM hub. (I just have to remember I haven't got front brakes when a smaller 26" wheel is in use).

Interesting read, tongxinpete.

Regarding beach / coastal plans: Yes. I've toyed with the idea of creating a '2 Wheel Drive' 2WD machine as a beach project. I have a stripped down, (as in lightweight), Powabyke Euro, (with lithium power / regular front wheel motorised hub), and have considered purchasing an old Mk1 Powabyke Euro to harvest its motorised rear wheel to create a dual drive Powabyke suitable for off road adventures.

Two independent Chinese 36v controllers and a throttle left and right seems like a plan!

My lightweight Euro currently wears 2.35 x 26" Schwalbe Big Apple tyres and they do traverse hard packed sand / shingle ... in certain conditions ... so I'd be fascinated to see how 2WD worked on Chesil beach!

 

[Deleted member 4366]

so I'd be fascinated to see how 2WD worked on Chesil beach!

You'd need tyres big enough not to sink in. I would guess that you need a fat bike with 4" tyres. Normal tyres are not too bad on sand, but shingle is different. Traction won't be a problem. My 2WD bike can climb a 14% hill on slippery snow. The wheels spin a bit, but they act like gyroscopes to hold you upright and in control.