BMS Bafang BPM 500w top speed?

First post from a newby. I'll be adding my build photos after this to offer something back to a very useful forum.

Just bought and fitted my second conversion kit. My first was a 36v 350w Mac fwd infineon controller using a Ping LiFePo 10ah that reaches 22mph on the flat. The new kit from BMS is a 36v KU123 500w Bafang BPM I 201 rpm. Unfortunately it's topping out at around 16/17mph. None of the various speed controls have been connected (speed limiter or 3 speed switch - it goes even slower when they're connected) and the motor or controller hardly get warm even after a steep climb even drawing 33 amps max!

My friend also built his second project which is a 48v KU123 500w Bafang BPM II (the new less shiny one) rwd 201 rpm as part of the same order. He can also only manage 16/17mph. He has a 48v 500w Mac rwd infineon kit that tops 27mph.

Any ideas why the performance is so poor for both kits? I've emailed Judy at BMS so hopefully will receive a reply. Is it restricted for the European market? Can I not expect much more from the 201 rpm?

If I can resolve this I'll be very happy with the kit that arrived quickly and in good order.

Welcome
I suspect you have a code 15 (slow wind). My code 10 will do 32mph with a 48V ping and a KU93 controller, 26" wheels. I use the speed switch wires to slow it down.
The code 8 (393rpm)is the opposite end of the scale, it's wound for a smaller diameter wheel and you would be hitting 34+ mph with it in a 26" wheel.
I think the only way to gain more speed is to up the voltage and fit a larger diameter wheel.
What number is stamped on the hub?

There was a good thread running covering this
http://www.endless-sphere.com/forums/viewtopic.php?f=3&t=35323

Code 10 is version for bafang BPM500 36V and code 13 is version for bafang BPM500 48V.

Thanks for that Wurly. It looks like there's a 13 stamped next to the 500w. I'm quite sure it is the slow wind motor. Oh well, all part of the learning curve. I'll either give it to my friend to over volt with his 48v or do more pedalling on the flat to break into a sweat!

Get your friend to buy it from you and get a code 8 (BMSbattery) or a code 10 from Michael(evassemble).
My code 10 would do about 22mph on 36V. A code 8 should go faster. It's probably going to work out cheaper to replace the hub, but the faster you go the more current you draw. How fast do you want to go?
I'm quite happy buzzing along at 24mph and it makes my battery happy too.

The 36v 201 rpm BPM is code 15. My code 13 will do 20mph at 36v. You can make the code 15 do about 20 mph with 12s lipos or about 24mph with a 48v battery, which would be closer to 60v hot off the charger. There's not much you can do with a 48v 201 rpm motor, but the same thing applies - more volts.

Once again, BMS Battery's unbelievably complex and obtuse motor code listings claims another victim.
It's been said here that it's really quite simple, but I beg to differ. I've been studying the numbers for months and I still find it confusing.
This is simple[From Cell-mans site for 500 Watt MAC motor]

QUOTE- "Specification:

6 turn high speed motor - 400rpm loaded at 36V

8 turn standard motor - 320rpm loaded at 36V

10 turn torque motor - 255rpm loaded at 36V

12 turn low speed extra torque motor - 200rpm loaded at 36V

Accepts disk brake and 7 speed freewheel with standard 135mm rear dropout.

As a guideline you can expect approximately the following real world speeds for the above windings on 12S LiFePO4 battery pack (approximately 38V under load) in a 26” rim on the flat, no pedaling with a rider plus bike weight of approximately 130kg total (286pounds):

6T - 45kph (28mph)

8T – 39kph (24mph)

10T – 32kph (20mph)

12T – 25kph (15mph)"- END OF QUOTE

Now THAT is simple. Why can't BMS Battery do the same???

I was taught many years ago in school that it is incumbent upon the speaker to make himself understood, it is not incumbent on the listener to decipher nonsense!

I was also taught that if you don't like something, you "vote with your feet" and go somewhere else.

So until such a time that BMS Battery decides to become customer friendly, the good readers here should spend a little more and buy the MAC from Cell_man and receive the added benefits of a better wheel build, after sales support and parts availability.

d8veh said:

The 36v 201 rpm BPM is code 15. ..

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I ordered 36V 350W 201 rpm and received 26(13), so there must be a difference between 350W and 500W as well as 36V and 48V

Motomech, I think you're being a little unfair on BMSBattery. For every motor the sell they quote the rpm at the rated voltage. It's us that make it complicated by talking about code numbers and then running at diferent voltages.

d8veh said:

Motomech, I think you're being a little unfair on BMSBattery. For every motor the sell they quote the rpm at the rated voltage. It's us that make it complicated by talking about code numbers and then running at diferent voltages.

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Codes are fine, actually they seem to be the wind counts, so there is nothing wrong with them. You can use the cellman's guideline or BMSBattery's no load rpm versus voltage, and still come to similar results. So a 10 turn MAC will be as fast as a 10 code BPM. As an owner of both, I can affirm this.

I recently bought the very same slow motor that the OP has, and power it with 12S lipo to get a top speed of 25-28kph. I gave it to my dad and he's very happy with it. Overvolt it with 24S lipo and low amps, and it will FLY!!! To each his own I guess.

Low speed better hll climbing without over heating. High speed no so good at hill climbing will over heat on hill. So it is always a trade off. Plus distant ? Nee sweat please teel us what please let us know about reply from bms battwery

I'll keep you updated 999zip999.

999zip999 said:

Nee sweat please teel us what please let us know about reply from bms battwery

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I think I know what the answer will be.

I don't want to ijack this thread, but it's relevant to BMSBattery. I wanted a 250w Bafang motor for disk brake. They told me to order the SWXU because it was disk compatible. I didn't think it was, but these suppliers can get non-standard or new things, so Took them at their word and ordered one but added a note to the order asking them to make sure the motor was for disk brake. When it came, it wasn't for disk brake, so I sent them an e-mail and their reply was that I got what I ordered. I sent another one with a copy of their instruction to order it attached, but I got another reply telling me I got what I ordered. My only option would have been to send it back and claim from Paypal, but the loss for the return shipping would have been too high, so I sold the kit on at a bit of a loss. I guess this sort of situation would be the same with many Eastern suppliers so be careful when ordering.

Heard back from BMS which was nice to respond so soon. They've said it should reach 25km/h which it does (think I've maybe confused them by quoting mph). They've also suggested another throttle, pas or checking the battery. I told them the problem is I've bought the wrong motor. I'll probably buy a new hub from evassemble although their 500w motor is sensorless so I'm not sure if it could be a straight swap in terms of size. Not sure if some of the speed controls on my ku123 sensorless controller will still work. The bms motor had hall sensors.

If someone can make ebikes simple they'll make a fortune! Or perhaps it's just me.

If you ask eva Michael for a code 10, you will get a code 10.
Although the BPM will be sensorless it'll work fine with a ku123 controller. The speed switch setting will also work. You will have roughly the same set up as me. With both white wires and the black green on the speed switch connected i get 24mph. Disconnected you'll get 30mph......
It should be a straight swap, are you going to get the hub or a complete wheel?
EDit:i should have said i'm running 48V, you are on 36V, expect around 23-25mph

Nee Sweat said:

Not sure if some of the speed controls on my ku123 sensorless controller will still work. The bms motor had hall sensors.

If someone can make ebikes simple they'll make a fortune! Or perhaps it's just me.

Click to expand...

The KU123 has automatic detection of hall sensors and will work OK without them.

Don't buy two motors from EVassemble at the same time. I did and they put them in one box with not enough separation so the spoke flanges got bent and dented. I had to send them back and I finally got my money back from Paypal. Luckily Fedex accepted some responsibility for the damage and sent them back FOC, but it took a lot of time and effort dealing with the three parties to get it sorted. None of them were very helpful apart from maybe Paypal, who just applied their rules without deviation.

d8veh said:

.... BMSBattery. For every motor the sell they quote the rpm at the rated voltage. It's us .....

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True, it seems, for the Bafang motors, but not for the Cutes. They list the Cute motors as "201" or "328"rpm. Various real world reports on E-S suggest they are approx 230 and 275rpm at rated voltage. d8veh, I think you have first hand experience of this from a "201" rpm motor?

marshy said:

d8veh said:

.... BMSBattery. For every motor the sell they quote the rpm at the rated voltage. It's us .....

Click to expand...

True, it seems, for the Bafang motors, but not for the Cutes. They list the Cute motors as "201" or "328"rpm. Various real world reports on E-S suggest they are approx 230 and 275rpm at rated voltage. d8veh, I think you have first hand experience of this from a "201" rpm motor?

Click to expand...

Yes, that's my point.
Cell_man list his no-load RPM numbers all at the same volts and wheel size. It then becomes a simple matter for the end user to apply those figures to calculate no-load numbers for the voltage and wheel size of their intended build.

BMS Battery only applies that standard to their small Bafang motors.
For them to list the Cute 36V/350W Q100's as a "201" and a '328" is meaningless[although it may be accurate for the 24V/250W Q100's].

Thanks Wurly. I was thinking about just buying the hub motor and replacing the motor in the conversion kit wheel I bought off bms. Looks like it should be about £60 cheaper than buying another kit but a bit more work.

A reduced speed of 22mph with the option to switch to a higher speed is what I'm after and thought I'd bought with the recent kit.

marshy said:

d8veh said:

.... BMSBattery. For every motor the sell they quote the rpm at the rated voltage. It's us .....

Click to expand...

True, it seems, for the Bafang motors, but not for the Cutes. They list the Cute motors as "201" or "328"rpm. Various real world reports on E-S suggest they are approx 230 and 275rpm at rated voltage. d8veh, I think you have first hand experience of this from a "201" rpm motor?

Click to expand...

My Cute motor is rated 201rpm at 24v. I have it in a 20" wheel and use 12S lipos at around 48v. Although I've never calculated, my understanding is that 201 rpm equates to the European standard of 15mph. So, I'd calculate my bike's speed as:
15 x 20 / 26 x 48 / 24 = 23.08 mph, which is very close to the speed I get of 20 - 22 mph in favourable conditions and about 24mph no-load.

Don't forget that batteries are nearly always quite a lot above their rated voltages so a 3.7 cell will be 4.2 hot off the charger.
201 x 4.2 / 3.7 = 228rpm. That's pretty close to 230 rpm. Maybe that's why.

Q100 24V/250W "201" "slow" wind

Ok, working backwards, the lazy way[Ebike CA sim.], I plug-in,

BMC V2 Spd. @ 90% throttle and,
@ 24 Volts, the
The no-load motor speed w/ 26" rim is 201 rpm :lol: which equates to the Euro legal 15.5 mph :lol: :lol:

Using D8veh's 20" wheel and 48V battery, we get.

A no-load motor speed of 23.5 mph :lol: :lol: :lol:

Confirmed 201 rpm @ it's rated voltage

Carrying on,
No-load motor speed @ 36 Volts is 290 rpm, which would a no-load speed w/26" rim of 22.5 mph. Correct?

And on,
No-load motor speed @ 48 V is 341.5 rpm, for a 26" rim no-load road speed of 25.5 MPH.

So, if the above is correct and if the Q100 36V/350W numbers mentioned before accepted, we get this short list,

No-load motor speed A@ 36V with a 26" rim

Q100 36V "201" = 230 rpm
Q100 36V "328" = 273 rpm
Q100 25V "201" = 290 rpm

Anything wrong with this list?

looks like the 24V slow wind Q100 @ 48V in a 26" wheel would be a nice fast wind mini-motor for those without severe hills to climb.

Yeah, the q100 24v on 48v would hit almost 30mph? Not sure how long it will last.