Bafang G3xx series high reduction ratio geared hub motors

[qwerkus]

The one issue will be the gears, the Bafang rating (on the SWXH at least) seems to be quite accurate, so you are limited in low down torque by them. If you don't mind having to run a larger and heavier DD then you will definitely be able to get more torque from one with ridiculous phase amps.

Thank you very much for your work. Awesome details. I'm very interested into that motor as a cargo puller, just like dogman. How about quality helical metal gears like those:

Together with oil cooling, it could work. At least that was the plan forthe heinzmann cargo, which still hasn't been released yet...

I wonder if there are some standart gear set out there, which would match the internals of the g360.

 

[1N4001]

Thanks wil for these tests. This appears to be an excellent motor indeed, probably capable of dethroning the MAC in the 4kg geared class.

How did you attach the temperature sensor, if I may ask? and what phase current do you run it at? Did you add oil cooling yet, and if so, which oil?

Thank you very much for your work. Awesome details. I'm very interested into that motor as a cargo puller, just like dogman. How about quality helical metal gears like those:

(...)

I wonder if there are some standart gear set out there, which would match the internals of the g360.

Those steel helical gears look very interesting. But bear in mind that the Bafang uses a two-stage reduction. You will very likely have to make your own custom gears.

But with that and oil cooling you can probably get ridiculous torque out of this small motor.

 

[wil]

How about quality helical metal gears like those:

I know at least one person put metal gears in a SWXH, they described it as sounding like a coffee grinder when actually riding, very loud. That would probably be the case here too, especially as only one of the stages is helical

How did you attach the temperature sensor, if I may ask?

I heatshrank the leads and epoxied the temp sensor to the stator/windings at the corner of where the winding passes through the stator. Then ran wires to the two points I mentioned in the pictures above.

One thing is that the temp sensor displays 20 degrees higher than it should, I'm not sure the reason, as I was expecting the thermistor to have the right parameters since it came from ebikes.ca.
Possibly I missed something on the hall sensor board I soldered it on to, but when I initially probed it after cutting the trace all connections seemed fine/no extra resistors connected etc.
It could also be because I'm using the ground coming from the controller as the gnd source, not from the cycle analyst itself (but this shouldn't matter really).

and what phase current do you run it at?

Only 30 amp phase until a decent torque arm arrives.

Did you add oil cooling yet, and if so, which oil?

No oil added yet, I want to get the setup finalised before I do because once it's in it becomes much more difficult to work with.
I realised there is no fill access once the motor is assembled, so I'll need to drill something, probably the disc mounts. On the SWXH these went all the way through the metal, but on the G360 they stop early.

 

[qwerkus]

How about quality helical metal gears like those:

I know at least one person put metal gears in a SWXH, they described it as sounding like a coffee grinder when actually riding, very loud. That would probably be the case here too, especially as only one of the stages is helical

LOL - true that. Yet I doubt it was quality helical gears. I've seen industrial motors running 10.000rpm + with super tight helical gears in an oil bath, and all you could hear is a slight buzz. Too bad no such gears are available for hub motors. CNC cut +/- 0.001mm helical steel gears, O ring rubber seals and easy to change oil bath - I still think this would be a game changer in the ebike industry. The main problem I guess is that the big names (Bosch, Brose and so) all went the proprietary mid drive way in face of chinese competition, so there is no one left (at least in europe) working on quality geared hubs. Maybe Heinzmann's, but there new cargo hub just doesn t leave development status...

Maybe a start would be to recycle the gears from a 7 or 8sp IGH. Those are pretty well cut.

 

[wil]

The torque arm has arrived and I've boosted power output!

Using this torque arm https://endless-sphere.com/forums/viewtopic.php?t=49635 I am a touch worried about engagement between the axle and nut. I only have enough axle length for 3/4 of the nut, with the only things on that side of the hub being 1 washer, the torque arm and the nut itself. Granted this is a quite wide torque arm but I think the shafts should have a bit more length from Bafang, my older SWXH had the same issues as well, I even stripped the threads slightly on the crank side.

Now running 30 amp + 60 phase amp on 20s LiPo. From a standstill or low speed the front end will get squirrelly / lift off. I think this is the most I will be able to get out of a 6 FET 4110 controller.

Once up to speed I'll sit at about 55km/h (on a 26" rim), using around 1kw constant. It would be good to increase this just for main roads sake with some extra voltage or a controller that can field weaken. The controller I have does not seem to have any issues running it even at top speed, so I think the stator design probably is not much of a reluctance design, despite being IPM. Maybe I would only notice this with field weakening though.

Even at this increased power I am shocked how silent the G360 is.

I am slightly concerned I'll strip gears, but I have a spare set so we will see. Does anyone know what torque / phase amps Macs or Bafang BPMs etc strip at? I'm trying to work out a safe level to run at, using the motor sim I would be at around 65nm now I think, which is above the 50nm rating Bafang gives.

 

[neptronix]

hm, try a grin tech torque arm if it's thinner?

Nobody knows what the G360 will take, you're the first test hamster :thumb:

55kmh from a motor that weight sounds pretty nice, the question is... does the motor get pretty toasty, or is it just lukewarm after a nice thrashing?

Your batt amp to phase amp ratio of 1:2 is perfect. If you want to help out the poor clutch, you can make it even gimpier; say..
30 batt amp
55 phase amp
This would subtract torque from mostly the lower RPM band. Go the other direction and you will add more low end torque ( more danger for the clutch ).

30A x 72v = 2160w, which is quite a lot of power for a motor rated at what, 750.. 1000?
What are your watts cruising at 55kmh?

 

[wil]

hm, try a grin tech torque arm if it's thinner?

The grin tech ones don't fit my dropouts unfortunately, mine are too "3D". I had v1 clones on originally but they had to face the wrong way so I don't think it would be doing much. Even the new one I had to grind out to fit around some welds.

Nobody knows what the G360 will take, you're the first test hamster :thumb:

I figure if it is the gears that give out it will be at about the same torque as other motors of this size, being the same material and all.

55kmh from a motor that weight sounds pretty nice, the question is... does the motor get pretty toasty, or is it just lukewarm after a nice thrashing?

Even my SWXH would get to 55, I just felt very bad for asking that much from it
So far I only did a 5km/10 minute test ride at this power, pretty much full power the whole way though. After which it was sitting at 65°C. (I think, the temperature sensor reads 20 degrees off when not heated, 15°C reads as 35°C, so I'm hoping it's a linear offset and the 85°C it reads is 65°C. I think this is due to using the controller ground vs cycle analyst ground for the probe.)

Your batt amp to phase amp ratio of 1:2 is perfect. If you want to help out the poor clutch, you can make it even gimpier...

It's much more fun than the 1:1 I was running previously to stop stripping on my SWXH. I do have a relativity slowly tuned throttle + PID so this should help the clutch a bit.

30A x 72v = 2160w, which is quite a lot of power for a motor rated at what, 750.. 1000?
What are your watts cruising at 55kmh?

Only rated 500w from Bafang
Sitting at 55 uses around 1100 watts.
Overall on this ride I was averaging 18wh/k. It also managed to use 1/5th my total battery capacity in 10 minutes, I might need to improve under...

 

[qwerkus]

I am slightly concerned I'll strip gears, but I have a spare set so we will see. Does anyone know what torque / phase amps Macs or Bafang BPMs etc strip at? I'm trying to work out a safe level to run at, using the motor sim I would be at around 65nm now I think, which is above the 50nm rating Bafang gives.

Interesting point. It depends on input power, but also a lot on nylon quality. From the pictures you took, I'd say the reduction gears are of medium to low grade finish. It might be as designed by bafang, in order to save the freewheel clutch. If the structure of the g360 is the same than the g310/g311, than the clutch is actually a one way bearing (or whatever they call it) on the inner border of the left cover. While nearly silent, IIRC, theses things are not nearly as strong as a ratchet system,and will probably be the main power limiting factor. Should you chose to hotrod the motor, I'd suggest removing the freewheel alltogether and use brake regen on this motor, just like the gmac, together with stronger pinions. Otherwise I seriously doubt you can outperform a MAC (of similar weight) with this hub motor.

 

[neptronix]

The grin tech ones don't fit my dropouts unfortunately, mine are too "3D". I had v1 clones on originally but they had to face the wrong way so I don't think it would be doing much. Even the new one I had to grind out to fit around some welds.

I've had issues like that and had to get tricky with spacers and other bits and pieces.
I always use grin tech torque arms as a base because they are the most snug. I have bought a dozen other brands over the years and it was a real waste of cash as they all had 0.5 - 1mm of play..

I figure if it is the gears that give out it will be at about the same torque as other motors of this size, being the same material and all.

I would personally aim for the power levels we see on MAC motors.

30A x 72v = 2160w, which is quite a lot of power for a motor rated at what, 750.. 1000?
What are your watts cruising at 55kmh?

Only rated 500w from Bafang
Sitting at 55 uses around 1100 watts.
Overall on this ride I was averaging 18wh/k. It also managed to use 1/5th my total battery capacity in 10 minutes

55kmh = 34mph in 'murica units and 1100 watts would be lower than the power consumption we see on a known 90% efficiency motor.

That CA calibrated correctly? or are you shaped like a stick figure? ( unusually low aerodynamic footprint )

 

[Alex W]

The G370 is really interesting, has anyone tried it yet? This looks like a nice hub for lightweight conversions. My everyday bike today uses a G311 and 2 LiGo batteries, but I have the Baserunner set to a max of 10 amps (around 360 watts), so a 2lb lighter and lower power hub would fit my uses very well. Total system weight for 2 Ligos, G370, and a Baserunner is about 3.1kg. Replacing a 400g dynohub means you can get an urban/commuter e-bike for only 6lb weight increase over the unassisted bike.

It's interesting that it is listed with 42NM torque, since the G311 is listed with 30NM torque (but measures at about 40). The unloaded RPMs are the same between the G311 and G370, while the G370 has a higher at load RPM, which also points to increased torque. Is this a real improvement, or just a change in measurement methodology?

 

[justin_le]

The G370 is really interesting, has anyone tried it yet?

You mean this little guy?


Cutest hub motor on the planet I'd say. When I'm finished the testing on it I'll be posting the results in this simulator thread here
https://endless-sphere.com/forums/viewtopic.php?f=2&t=100461

It's interesting that it is listed with 42NM torque, since the G311 is listed with 30NM torque

I reallly think that this is either a typo or an inconsistent evaluation metric, though testing will reveal soon enough. The G370 rotor is so much smaller in diameter (40mm, vs 60mm for the 311) that it's hard to see even with it's increased thickness and increased gear reduction ratio (about 14:1 vs 11:1) that it would really wind up as a higher torque motor in a normalized comparison to the G311.

 

[wil]

55kmh = 34mph in 'murica units and 1100 watts would be lower than the power consumption we see on a known 90% efficiency motor.

That CA calibrated correctly? or are you shaped like a stick figure? ( unusually low aerodynamic footprint )

Yeah, should be correct, I have exact tyre dimensions + the the controller shunt was measure and is not just an approximate guess. My bike is a mountain bike, but has a longer bar reach than normal, so I am more lent over than would be considered full upright.
I didn't really think about it, and was pedaling at the time (around 100 watt) + I checked grade at that location and it was -0.5%.
I re-ran somewhere with 0% grade and without pedaling and I sit on a steady 1300 watt at 55.

Jusin has the G360 on the sim now, (Thanks Justin, all of your simulators are so helpful!) sim-ing it puts me puts me halfway between a tuck and upright on the motor sim for reference.

I plotted a ride out the other day

It's a bit of a mess, data is out of Strava visualised over the trip sim of the same route. Trip sim obviously isn't the most accurate representation of real life, as it uses full power where it could not be used in real life etc, but from a temperature perspective it's pretty spot on in this regard.

Top graph I have plotted real speed over the top of simulated speed.
I've combined bottom graph to show both Grade and Shell temp.

After a 2km 4% average grade segment at full power core temp got to 65 C, pretty much bang on the sim.

By the end of the ride I had hit 85 C and started throttling. There was a 1 km segment at 10km/h average speed almost purely on motor power (super tough terrain) which didn't help with temperatures.

Overall ride time was 21 minutes. Despite the core being hot, the cover felt no hotter than at the beginning of the ride. From here the motor definitely needs an oil fill to help increase thermal conductivity.

 

[neptronix]

I love how you have the data to prove your case
Okay, so more like 32mph at 1100w then? makes sense. That's pretty decent efficiency actually.

 

[Bequmi]

Wil, correct me if I'm wrong, but you ordered the 260rpm version correct? Seeing as you're topping out around 34mph at 72v right now, do you have any best guess or recommendation for what rpm I should try to get for a goal of 28-30 mph at 52v?

Maybe order a 300 rpm?

This will be going into a 700c wheel with 2" schwalbe big Ben tires on it.

I could go your route and bump up to 60v/72v, but sticking with 52v seems all around easier at this point.

 

[neptronix]

The G310 is on the ebikes.ca motor sim. It can help you answer these questions:

https://www.ebikes.ca/tools/simulator.html

 

[Bequmi]

Thanks for the info. The g360 is also in there, but the disconnect between what motor voltage (Kv) rpm is input and what quoted rpm version motor from bafang is what seems to be my issue. It's seems the 11t version in the simulator is showing 9.18rpm/v which should equate to a 330rpm motor (from bafangs system) at 36volts correct? Or is my estimation wrong?

I guess I'm just having a hard time knowing if I should go for a motor at a quoted rpm of 330@36 volts and trust that it should come out to 9rpm/v or if that 330rpm will be way to much for such a big wheel.

 

[neptronix]

rpm/v is quoted as a no load speed. The loaded speed will be something like 80% of that.

ebikes.ca's sim is very close to reality in my experience.

 

[Bequmi]

rpm/v is quoted as a no load speed. The loaded speed will be something like 80% of that.

ebikes.ca's sim is very close to reality in my experience.

Thanks for the info. I am still in the heavy learning phase. Thus I'm having difficulty finding the differences between Bafang's listed available RPMs and the Kv of the motor within the sim. I'm thinking that maybe a motor with approximately 9rpm/v at 52v should get me to what I'd like. Does this seem reasonable? Is my assumption that this should equate to a rated motor of 320/330rpm @36v from Bafang (essentially the 11t that Justin has listed)

I hope my questions aren't too rudimentary. I appreciate your help!

 

[neptronix]

If you hit 'advanced', you can see the kv the motor is listed at
Also, by moving the dotted line that indicates your load to the end of the curve, it should show approximately what a no load RPM for that voltage looks like.
You can then calculate kv by doing rpm / voltage

Yeah there is a lot to learn. I spent 6 months learning before i built anything. Best wishes on your journey, sir.

 

[Bequmi]

If you hit 'advanced', you can see the kv the motor is listed at
Also, by moving the dotted line that indicates your load to the end of the curve, it should show approximately what a no load RPM for that voltage looks like.
You can then calculate kv by doing rpm / voltage

Yeah there is a lot to learn. I spent 6 months learning before i built anything. Best wishes on your journey, sir.

I'd seen the advanced menu and kv settings, but didn't realize about that slider and showing no load RPM at the end. That's super helpful! Thanks for that.

Looks like the g360-11t is showing 340rpm @ 36v. That makes me think my estimation of a 320-340rpm rated motor (@36v) from bafang is probably about the right item to equate to the 11t motor. Hopefully at least!

I've been at it about half that long now, and finally getting ready to start ordering parts!

Thanks again!

 

[wil]

Thanks for the info. The g360 is also in there, but the disconnect between what motor voltage (Kv) rpm is input and what quoted rpm version motor from bafang is my issue. It's seems the 11t version in the simulator is showing 9.18rpm/v which should equate to a 330rpm motor (from bafangs system) at 36volts correct? Or is my estimation wrong?

Mine is the slow, 260 rpm version.

The 11t on the sim does seem to be a 330rpm @ 36v, so 9.16rpm/v.

Bafang only seems to offer 260 or 420 rpm versions, and the supplier I bought from also only could offer those two.
They are also rated at 36, 43, 48 volts.

Plugging those numbers in, the ones that get closest to Justin's motor is 48v, so I think these are the values Bafang is now using for calculation (clear as mud right?).

Problem: My 260 rpm motor. With the same method it would be at 5.5rpm/v, which is blatently wrong, I wouldn't be able to hit 40km/h, let alone 60km/h. The 6.6rpm/v I measured earlier also can't be correct because I would only be able to get to around 45km/h. The only thing that really seems to make sense is if my motor is rated at 36 volt, 7.2 rpm/v, so ignore my 6.6rpm/v from earlier. It might be that my controller could not drive fast enough at upper RPM hence where I got 6.6rpm/v from.

If you do end up getting a G360 I'm interested how much you will be charged - my "sample" was $120 USD for motor + $20 for spare gears + $113 USD postage

 

[Bequmi]

Thanks for the info. The g360 is also in there, but the disconnect between what motor voltage (Kv) rpm is input and what quoted rpm version motor from bafang is my issue. It's seems the 11t version in the simulator is showing 9.18rpm/v which should equate to a 330rpm motor (from bafangs system) at 36volts correct? Or is my estimation wrong?

Mine is the slow, 260 rpm version.

The 11t on the sim does seem to be a 330rpm @ 36v, so 9.16rpm/v.

Bafang only seems to offer 260 or 420 rpm versions, and the supplier I bought from also only could offer those two.
They are also rated at 36, 43, 48 volts.

Plugging those numbers in, the ones that get closest to Justin's motor is 48v, so I think these are the values Bafang is now using for calculation (clear as mud right?).

Problem: My 260 rpm motor. With the same method it would be at 5.5rpm/v, which is blatently wrong, I wouldn't be able to hit 40km/h, let alone 60km/h. The 6.6rpm/v I measured earlier also can't be correct because I would only be able to get to around 45km/h. The only thing that really seems to make sense is if my motor is rated at 36 volt, 7.2 rpm/v, so ignore my 6.6rpm/v from earlier. It might be that my controller could not drive fast enough at upper RPM hence where I got 6.6rpm/v from.

If you do end up getting a G360 I'm interested how much you will be charged - my "sample" was $120 USD for motor + $20 for spare gears + $113 USD postage

Thanks for the detailed info!

I think then potentially the one in the simulator could be a 48v 420 rpm version? (9.18x48v = 440rpm)

I have requested information on the available windings and rpm options and I've gotten two responses. They offer 260-420 and that they offer rpm windings at different voltages(36/43/48 like you said) that range from 260 to 420. I clarified this by asking if I could order two different motors rated at 36v @270rpm and 36v @290rpm and was told that I would receive two different motors. So potentially that means that you can choose different speeds than just the 260/420.

I asked for clarification on what they would call a 11t wind model and was just requested to give them a voltage and speed goal, which isn't very helpful, so I asked for rpm recommendations for the following motor speeds.

35km/h at 36v
35km/h at 48v
40km/h at 36v
40km/h at 48v
45 km/h at 48v

I haven't heard back yet as this is a holiday weekend and they have to get the info from bafang directly. Here's to hoping I get some useful information!

They quoted me a price of $148 per motor (originally quoted $120 but the clarified that the cost from bafang had gone up and was now $148.)
Gears were $20 and shipping ranged from $80 for 2, $126 for 3, and $179 for 6. This is DHL 5-7 day door to door shipping.

How do you think your 260rpm version would do speed wise in a 29er tire at 52v? Do you think a 280/300rpm version would be better if it's available?

 

[wil]

How do you think your 260rpm version would do speed wise in a 29er tire at 52v? Do you think a 280/300rpm version would be better if it's available?

Depends on your goals! Way too slow I think for me personally). I think mine would actually suit a 29er more than a 26" at the 75v I run so that at full speed it would be at a point with higher power available.

This is the two at 52 volts in 29" wheels https://www.ebikes.ca/tools/simulat...tothrot=false&throt=100&wheel=29i&wheel_b=29i
If I was limited to 52v I think I would go for an even faster wind than the 420/9.18, but you would probably want a bigger controller at that point.

Even at 75v, 29" tires I think the 420 would be better than the 260 I have, (IF your aim is purely go as fast as possible), peak power peaks at peak load (on a flat). https://www.ebikes.ca/tools/simulat...0&throt_b=100&frame_b=mountain&frame=mountain.

The main advantage to the slower wind is higher torque from lower battery current, but the faster motor still hits 60nm on phase torque of 60amp, above which the gears probably are going to give up anyway so this advantage is lost and you end up with the faster motor being better because your power is available over a wider range higher up.

The other difference is efficiency, the slower wind at all speeds will be slightly more efficient, looks about 1 - 1.5%. This means less heat which is a big thing with geared hubs, and more range. Weigh up your average speed and grade for this, if you are averaging 30km/h than the slower motor will actually be better as it will be more efficient. (On the sim use a voltage throttle for this)

Essentially you will just need to weigh up your goals, if you want to go as fast as you can the 420 is better, if you want to ride it at anything other then maximum speed the slower wind may be better. On my bike in real life I will tend to average around 25-30km/ because I'll be on bike paths etc.

One thing is, I'm not sure how the G360 will handle a real FOC controller with field weakening applied. If the motor does have a reluctance component than I think the slower motor may excel as it's usable power range may extend fairly substantially. I'm waiting on the mother FOCer project going on at the moment for this (or someone with more expertise to say I'm wrong)

 

[Bequmi]

Depends on your goals! Way too slow I think for me personally). I think mine would actually suit a 29er more than a 26" at the 75v I run so that at full speed it would be at a point with higher power available.

Essentially you will just need to weigh up your goals, if you want to go as fast as you can the 420 is better, if you want to ride it at anything other then maximum speed the slower wind may be better. On my bike in real life I will tend to average around 25-30km/ because I'll be on bike paths etc.

I'd like to have the option to hit maybe 32 mph on the top end. I don't think I'd need anything more than that, and if I did I'd probably need to put it in a full suspension bike.
Cruising speed of 26-30 would be great. Currently my average speed is about 15-18 mph depending on route, and that's with a bike running a bafang cst that tops out at 26mph.

Batteries are still on the table too right now, so I could go with any option really (48 / 52 / 60 / 72)
My pack will be Panasonic 10a GA cells run 5-6 in parallel, so that limits my amp draw probably around 30-40 at max for longevity.

Thanks for your input Wil. Hopefully I get more info from Gomax within the next couple of days about rpm windings.

 

[Alex W]

The G370 is really interesting, has anyone tried it yet?

You mean this little guy?

I reallly think that this is either a typo or an inconsistent evaluation metric, though testing will reveal soon enough. The G370 rotor is so much smaller in diameter (40mm, vs 60mm for the 311) that it's hard to see even with it's increased thickness and increased gear reduction ratio (about 14:1 vs 11:1) that it would really wind up as a higher torque motor in a normalized comparison to the G311.

I had the same guess of it being a different metric, but one can always hope. I look forward to your analysis and hope you offer them (unless it is a total dog of course). It looks ideal for light e-bikes (~15kg), an important market for DIY since there are so few commercial offerings.