1000W hub motor options

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headwind   10 W

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1000W hub motor options

Post by headwind » Mar 25 2018 6:48am

Hi. Could I please get some advice about upgrading my hub motor? Surprisingly, it's not because I am chasing more power! My current Bafang BPM has enough power but it's pretty whiney, so I'm hoping for something quieter. Any suggestions please? Perhaps an eZee 250/350? Or a GrinHub?

A key factor is the winding. Initially I had a Code 12 version of the BPM, but it ran out of puff at about 35 km/h (in a 700C wheel). However, the faster Code 10 version suits my riding style perfectly.

In case it's relevant, the battery is 44v Lipo (RC- Zippy) and the controller is set to 25 amps.

Thanks.
Hybrid commuter: BPM 36V500W rear hub motor, 12S 8Ah LiPo

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dogman dan   100 GW

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Re: 1000W hub motor options

Post by dogman dan » Mar 25 2018 8:09am

Typical 500w rated dd hubs are ideal for running 1000-1500w. Even pushing them to 2000w works for shorter rides. So no need for a "big" direct drive motor for your needs. You got 1100 watts peak now.

So that's stuff like 9 continent, or even the cheapo "1000w kit" motors the factories in china put out in the millions, if not billions. If you like grin products, get a 9 c from them.

Quieter than any geared type motor, but some drawbacks like lack of the great coasting you get with geared. Often less efficient for stop and go rides, but great efficiency on a long cruise. Choose the winding based on your desired top speed on 48v. 6 turn if you want to cruise 30 mph.

Open up that bafang, and re grease the gear ring. That will help the whine a lot. But the geared motors are not the best choice, if you want to cruise quiet at full speed. They shine best when the speed is lower, and the ride is stop and go. Like city riding, or twisty single track. If you want that really quiet, but not completely silent ride, you need to go dd.

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Re: 1000W hub motor options

Post by wesnewell » Mar 25 2018 9:23am

Need Advice? https://endless-sphere.com/forums/viewt ... =3&t=66302
Mongoose 26" Ledge 2.1 mtb bike $99, yescomusa.com 48V 1000W rear hub kit $200, Hua Tong 72V 40A controller $35, 10ah 24s lipo $217=~43mph, range=45 miles @ 20mph. 25K miles and still going strong.
Huffy Fortress 3.0 with MXUS 3000 4T motor, 24s lipo, 96V 60A controller. Total cost with extras <$700. Top speed ~50mph
My videos https://www.youtube.com/channel/UC0KW4U ... _G2wQhptMg

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headwind   10 W

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Re: 1000W hub motor options

Post by headwind » Mar 26 2018 5:15am

Thanks for the replies.

Dan, I'm glad you mentioned the coasting limitation of a DD motor, I'd forgotten about that.

Regarding the number of turns, could you please check my calc for the RPM per volt of the Code 10 Bafang is correct?
Code 10 = 300 rpm (link) @ 36 volts
............. = 8.3 rpm per volt ?
Which roughly ends up as a 7 turn for a 25 mph cruise (48v, 700C wheel).

As suggested, I'll start with greasing the Bafang gear ring to reduce the whine. That would be much easier than swapping motors... Fingers crossed!
Hybrid commuter: BPM 36V500W rear hub motor, 12S 8Ah LiPo

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dogman dan   100 GW

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Re: 1000W hub motor options

Post by dogman dan » Mar 26 2018 8:01am

Sounds about right for the turns. But bear in mind, that a faster wind on a geared motor tends to result in a bike that cruises fast, but takes off very anemic.

And, even new and greased, a geared hub motor will make a lot of noise compared to DD, at 25 mph. Whatever the wind, at that speed the gears are wailing at higher rpm.

Eliminate the poor coasting of any dd motor simply by applying a tiny tickle of throttle when coasting. It wont cost much power, its just making the motor spin enough to catch up with the wheel rpm. At speed, the dd will be much quieter. There will also be less sluggish takeoff when using low turn motors, because the motors much larger magnets and more copper wire will pull harder.

For sure though, open the motor. For many its very easy to open the core to expose just the gears. Push the grease back onto the metal ring. It should help. Replacing worn gears is not too hard either, if they look thrashed.

I have to say, if you want fast and more quiet, time to try a cheap dd kit, or bare dd motor.

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Re: 1000W hub motor options

Post by amberwolf » Mar 26 2018 9:20am

For the quiet, a sine controller would probably make a difference, if you're using a trapezoidal one now.

Even a "quiet" DD motor would still "hum" or "buzz" with a trap controller, where it may be really quiet with a sine.

(pretty much everything I've ever used in BLDC motors has sounded like there was at least one bee trapped inside, and some of them like a small swarm, because they're all run on trapezoidal controllers. Eventually I'll be using sine controllers on the trike's MXUS motors, which should make the ride much quieter).

Also, some bike frames are prone to resonance inside, so the motor noise coupled to the frame makes the whole thing louder. In some cases it's been found to help this by injecting expanding foam insulation into the stay tubes (via the existing weld-relief holes, for instance).

John in CR   100 GW

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Re: 1000W hub motor options

Post by John in CR » Mar 27 2018 12:04am

Do a partial fill of your BPM with ATF and it will make it much more quiet as well as make it dissipate heat better. Cheap and easy.

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headwind   10 W

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Re: 1000W hub motor options

Post by headwind » Mar 27 2018 2:25am

Yes, I have a Grin sinewave controller to swap in, hopefully that will also help.

Sorry, not a chance I am using ATF!! I've done that before, and the mess it made was diabolical.
Hybrid commuter: BPM 36V500W rear hub motor, 12S 8Ah LiPo

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headwind   10 W

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Re: 1000W hub motor options

Post by headwind » Apr 12 2018 5:20pm

Update: So I added some grease to the Bafang. Whoever assembled the motor managed to get grease everywhere except for the gear teeth!

The grease quietened it a bit. Also I've ordered a MXUS DD motor, so I'll switch to that in future.

Thanks for all the advice.
Hybrid commuter: BPM 36V500W rear hub motor, 12S 8Ah LiPo

John in CR   100 GW

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Re: 1000W hub motor options

Post by John in CR » Apr 12 2018 9:00pm

headwind wrote:
Mar 27 2018 2:25am
Sorry, not a chance I am using ATF!! I've done that before, and the mess it made was diabolical.
It sounds like you didn't seal it properly. OTOH if it caused a motor malfunction I'd like to hear about it.

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