My RC Mid Drive with Single Stage Reduction

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crossbreak   100 MW

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Re: My RC Mid Drive with Single Stage Reduction

Post by crossbreak » Nov 15 2019 2:01pm

this looks a lot like the planetry gear reduction of a geared hub motor, fixvid. I build quite a few bikes with such a gear reduction with success, there is a very long thread linked in my signature.

BalorNG   10 mW

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Re: My RC Mid Drive with Single Stage Reduction

Post by BalorNG » Nov 15 2019 3:03pm

Have you considered a plastic chain?

https://www.rollerchain4less.com/35p-ac ... chain-10ft

Silent, self-lubricating, and seems rated for what you desire. Lighter as well, obviously.
Can be combined with a 3d printed plastic sprocket I presume.

If I knew about existence of such chains before I've ordered a planetary gear reducer, I think I'll be using one instead.

aCeMadMod   1 kW

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Re: My RC Mid Drive with Single Stage Reduction

Post by aCeMadMod » Nov 15 2019 8:21pm

Hi they shit chians plastic.only hold 3 times has less steel chian
I broken steel chian h25# before
It use less use for this app.

You can get 2 chians in one.

Not wight saveing.


Good luck all

BalorNG   10 mW

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Re: My RC Mid Drive with Single Stage Reduction

Post by BalorNG » Nov 16 2019 4:20am

We just need to compare peak chain tension with rated tension, leave a healthy margin and see results.
Since this is a low-power ASSIST, not 3+wk beasts, and with a single stage reduction, it should theoretically suffice, there are precedents with using PURELY plastic chains in first stage reduction, and this one (steel sideplastes/pins) is rated for FAR more than that.
Btw, all 'crank drives' are technically two-stage reduction :)

fixvid   100 mW

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Re: My RC Mid Drive with Single Stage Reduction

Post by fixvid » Dec 03 2019 3:34pm

New toy time:

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This puppy with chinese pedigree is very close in size to the orange D5035 but it's much heavier(~+250g) and at half the price! I wonder if it's more copper in there.. I didn't test it yet cuz i had a hell of a time enlarging the 8mm ID of 11t sprocket to 10mm as this motor's shaft.

thepronghorn   100 W

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Re: My RC Mid Drive with Single Stage Reduction

Post by thepronghorn » Dec 03 2019 5:27pm

fixvid wrote:
Dec 03 2019 3:34pm
New toy time:

....

This puppy with chinese pedigree is very close in size to the orange D5035 but it's much heavier(~+250g) and at half the price! I wonder if it's more copper in there.. I didn't test it yet cuz i had a hell of a time enlarging the 8mm ID of 11t sprocket to 10mm as this motor's shaft.
5035 is probably the stator dimensions of the orange motor - 50mm diameter, 35mm length. Going by that, this motor looks like it has 15mm more stator which should give it 15/35=43% more torque capability for the same heat dissipation. While you have it open, would you measure the lamination thickness?

These motors are also often referred to by their outer dimension aka 6384=63mm diameter, 84mm length. The orange motor is a 6355. The 6384 should have much more torque than a 6355.

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Re: My RC Mid Drive with Single Stage Reduction

Post by BalorNG » Dec 03 2019 6:27pm

I think that goes outside of the scope of lightweight pedal assist.
Note it has nearly 2A of no load current, for instance.

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Re: My RC Mid Drive with Single Stage Reduction

Post by FZBob » Dec 03 2019 8:49pm

fixvid wrote:
Dec 03 2019 3:34pm
This puppy with chinese pedigree is very close in size to the orange D5035 but it's much heavier(~+250g) and at half the price! I wonder if it's more copper in there.. I didn't test it yet cuz i had a hell of a time enlarging the 8mm ID of 11t sprocket to 10mm as this motor's shaft.
Nice find! Compared to the Turnigy 6374 130Kv I've been using for a while, it looks like it's only 5% (48gm) heavier and it has about 22% more stator volume. 120KV is a bonus. Did you get it off EBAY?

By the way, https://electricscooterparts.com/sprock ... motor.html has a selection of #25 sprockets with 10mm bores.

Looking forward to hearing your results!

fixvid   100 mW

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Re: My RC Mid Drive with Single Stage Reduction

Post by fixvid » Dec 04 2019 8:45am

Whoah i think we are going too far with the numbers here.. this motor is just a little bit longer than D5035. I expect it to be a little more torquier but i don't think it's stronger than Turnigy 6374. It would be too good to be true at half the price of Turnigy motors.

Still, i do think that a motor like this could be a good choice for cheap and light crank drive because it compensates for the lack of reduction.

I dont think i could measure realiably the lamination thickness, any tip ?

..and because you we're asking nicely:
https://www.aliexpress.com/item/3301140 ... 4c4ddB5VRX

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Re: My RC Mid Drive with Single Stage Reduction

Post by FZBob » Dec 04 2019 4:12pm

fixvid wrote:
Dec 04 2019 8:45am
Whoah i think we are going too far with the numbers here.. this motor is just a little bit longer than D5035. I expect it to be a little more torquier but i don't think it's stronger than Turnigy 6374. It would be too good to be true at half the price of Turnigy motors.
I borrowed some pics of the Turnigy 6374 from the eSk8 website just for comparison.
c65b7b8a671f3e026e82b310dc234fb40cdf0fdb_2_846x748.jpeg
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03456efbbc41d839f6df62a899dd922e5472818d_2_954x750.jpeg
03456efbbc41d839f6df62a899dd922e5472818d_2_954x750.jpeg (360.43 KiB) Viewed 1871 times
fcd4e0be45c459b7c5bb2efdfc00c4b101917ff6_2_1035x583.jpg
fcd4e0be45c459b7c5bb2efdfc00c4b101917ff6_2_1035x583.jpg (382.41 KiB) Viewed 1871 times
I think stator volume is probably a reasonable metric to compare motors (assuming other parameters are similar). Here are some rough stator dimensions from my motor spreadsheet. I didn't measure them myself, but I think they are in the ballpark. The Power (watts) numbers are the max burst (a few seconds) I have seen from my Turnigy wattmeter from all my rides. Note that I only use high power for short bursts (a few seconds), as I don't want to cook anything.

Turnigy 6354_________Dia: 50 Length: 25.6 Vol: 50 Pwr: 430

Turnigy D5035 Orange_Dia: 50 Length: 35.6 Vol: 70 Pwr: 557

Turnigy 6374_________Dia: 50 Length: 45.9 Vol: 90 Pwr: 655

Mystery 6384_________Dia: 53 Length: 50.5 Vol:111 Pwr: ???

The Turnigy motors all have internal fans, and some dust shielding. I think they may be more reliable/durable long term, and "may" cool better, at the expense of some weight and volume. The Mystery motor seems to pack a lot of stator into a small volume. I would bet that the Mystery motor could put out close to 750 watts (burst) if the VESC doesn't fry...

Might be interesting to pair up with a VESC 6 which I believe will handle more power...

All that being said, I like the color, and the price at your link is amazing, so I just ordered one. Merry Christmas to me!

fixvid   100 mW

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Re: My RC Mid Drive with Single Stage Reduction

Post by fixvid » Dec 05 2019 4:24am

FZBob wrote:
Dec 04 2019 4:12pm
All that being said, I like the color, and the price at your link is amazing, so I just ordered one. Merry Christmas to me!
And you din't even wait for my review .. may Aliexpress fulfill your wish :lol:

This motor has really the biggest stator of all with the outside dimension being roughly equal to D5035. There is a catch .. the rotor is not suported on both ends of the axis as Turnigy ones.. and sometimes when i spin the motor with my hand i hear something inside, like something is trapped between the rotor and stator. In normal use it was all right.

Image


So i enlarged my 8 mm slot to 10mm and mounted the new motor. Spinning it without chain at a specific rpm the whole frame resonated. I thought that's a balance problem and probably i will feel it while pedaling. Boy i was wrong.. for inexplicable reasons this motor is sooooo much smoother then the Turnigy one that i couldnt believe: belt like experience. Even the sound is much better and more quiet too.

Image

Image

The only difference is that i use 11t sprocket instead of 10t, but i remember using the same on D5035 and it wasnt even close. I tested it sensorless and with the same phase current of 30A. I would say that in this unfair configuration it's a little bit behind D5035 but very close in terms of torque (because of the bigger sprocket). So it seems that it's a little more efficient. I didn't test it with higher phase current but i suppose it has to better otherwise i see no reason for the bigger stator.

Until now i managed to get away without supporting the end of the shaft because it's a little more thicker at 10mm. I will test at 50A phase current and get back with some results.

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Re: My RC Mid Drive with Single Stage Reduction

Post by BalorNG » Dec 05 2019 9:31am

How much real no-load draw does it have?
I've tested this one with a wattmeter:
https://aliexpress.com/item/4000119983883.html

And got 1.5A, which is reasonable.
Btw, it leaks a lot of magnetic field outside.

fixvid   100 mW

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Re: My RC Mid Drive with Single Stage Reduction

Post by fixvid » Dec 05 2019 9:58am

BalorNG wrote:
Dec 05 2019 9:31am
How much real no-load draw does it have?
I was playing with it on VESC application and with a 14v power supply it was showing a power of ~3w. I didn't hook up a power meter but 1.5A seems too much for no load current. Maybe you were using more input volts, i'm not sure.

I see metal chips sticking to the rotor, but Turnigy was also leaking some magnetic field. I'm just worried because of the venting holes on the bottom, something will get inside and will frock up the very tight tolerance between rotor and stator. I will print a plastic cup and at least seal that part. There is another ~0.5mm gap between rotor and stator at the top, but that one is much harder to seal because one is turning, the other not. From this point of view Turnigys are better sealed and i would say splash proof. Not this one.

BalorNG   10 mW

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Re: My RC Mid Drive with Single Stage Reduction

Post by BalorNG » Dec 06 2019 4:33am

Don't trust the VESC, it also 'told' me something like 6 watts, while my wattmeter showed ~35.
I've used 25v, btw, but as I understand, it will draw same amps at FULL speed no-load on any voltage, because no-load speed losses (hysteresis and eddy currents) are linear with speed, and more volts - more speed.
If you use throttle to vary speed, current draw vary accordingly... please test no-load current using a wattmeter, I'm interested whether I 'overpaid' 50$ :)

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Re: My RC Mid Drive with Single Stage Reduction

Post by FZBob » Dec 06 2019 4:19pm

fixvid wrote:
Dec 05 2019 4:24am
[And you din't even wait for my review .. may Aliexpress fulfill your wish :lol:
What can I say - I'm a sucker for a sexy motor!

Do you happen to know the keyway dimensions? (Hopefully 3mm wide...)

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Re: My RC Mid Drive with Single Stage Reduction

Post by thepronghorn » Dec 07 2019 3:34am

fixvid wrote:
Dec 05 2019 4:24am
....

The only difference is that i use 11t sprocket instead of 10t, but i remember using the same on D5035 and it wasnt even close. I tested it sensorless and with the same phase current of 30A. I would say that in this unfair configuration it's a little bit behind D5035 but very close in terms of torque (because of the bigger sprocket). So it seems that it's a little more efficient. I didn't test it with higher phase current but i suppose it has to better otherwise i see no reason for the bigger stator.

Until now i managed to get away without supporting the end of the shaft because it's a little more thicker at 10mm. I will test at 50A phase current and get back with some results.
The 5035 and 6384 have very similar kVs at 120 and 125, so one would expect very similar torque at the same current. The 6384 probably has much lower phase resistance though, so it should be much more more efficient at the same torque. Would you be able to measure and report the phase-phase resistances of each motor?

Thanks!

fixvid   100 mW

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Re: My RC Mid Drive with Single Stage Reduction

Post by fixvid » Dec 07 2019 5:43am

FZBob wrote:
Dec 06 2019 4:19pm
Do you happen to know the keyway dimensions? (Hopefully 3mm wide...)
No keyway -> D-shaped shaft. I have 3 grub screws holding on it. No problems until now.
BalorNG wrote:
Dec 06 2019 4:33am
please test no-load current using a wattmeter, I'm interested whether I 'overpaid' 50$
I will put at least a clamp meter on the wires and check for current.
thepronghorn wrote:
Dec 07 2019 3:34am
Would you be able to measure and report the phase-phase resistances of each motor?
Im not sure about this one, you mean the 3 coil resistance of the stator ?

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Re: My RC Mid Drive with Single Stage Reduction

Post by k.m » Dec 09 2019 11:59am

It's possible to measure the coil resistance with Vesc Tool (FOC Detection).
I think the shown resistance value is for one coil in star/wye connection,
so phase to phase resistance it's twice this value.
Here are some example values for higher KV motors:
https://vesc-project.com/node/811#comment-form

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Re: My RC Mid Drive with Single Stage Reduction

Post by BalorNG » Dec 26 2019 4:19pm

fixvid wrote:
Dec 07 2019 5:43am
BalorNG wrote:
Dec 06 2019 4:33am
please test no-load current using a wattmeter, I'm interested whether I 'overpaid' 50$
I will put at least a clamp meter on the wires and check for current.
Hey, so, did you test it? My Flipsky motor came with defect halls... got a bit of a compensation, but still bit disappointed.

fixvid   100 mW

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Re: My RC Mid Drive with Single Stage Reduction

Post by fixvid » Dec 28 2019 2:24pm

BalorNG wrote:
Dec 26 2019 4:19pm
fixvid wrote:
Dec 07 2019 5:43am
BalorNG wrote:
Dec 06 2019 4:33am
please test no-load current using a wattmeter, I'm interested whether I 'overpaid' 50$
I will put at least a clamp meter on the wires and check for current.
Hey, so, did you test it? My Flipsky motor came with defect halls... got a bit of a compensation, but still bit disappointed.

Hi BalorNG,

Sorry for late reply, but i left my bike in my work town and now i'm home, so it will be a few weeks until i get back.

fixvid   100 mW

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Re: My RC Mid Drive with Single Stage Reduction

Post by fixvid » Feb 19 2020 3:55am

BalorNG wrote:
Dec 05 2019 9:31am
How much real no-load draw does it have?
I've tested this one with a wattmeter:
https://aliexpress.com/item/4000119983883.html

And got 1.5A, which is reasonable.
Btw, it leaks a lot of magnetic field outside.
Hi Balor

I managed to measure the no load current of this chinese 6384. At 14.5v supply i got 0.8A current consumption.

I still think this motor beats everything in this price range. It has enough torque, sounds good and is cheap. Wouldn't go back to turnigy in this setup.

FZBob
Did you get the motor? What are your impressions ?

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Re: My RC Mid Drive with Single Stage Reduction

Post by BalorNG » Feb 23 2020 4:26am

fixvid wrote:
Feb 19 2020 3:55am
BalorNG wrote:
Dec 05 2019 9:31am
How much real no-load draw does it have?
I've tested this one with a wattmeter:
https://aliexpress.com/item/4000119983883.html

And got 1.5A, which is reasonable.
Btw, it leaks a lot of magnetic field outside.
Hi Balor

I managed to measure the no load current of this chinese 6384. At 14.5v supply i got 0.8A current consumption.

I still think this motor beats everything in this price range. It has enough torque, sounds good and is cheap. Wouldn't go back to turnigy in this setup.

FZBob
Did you get the motor? What are your impressions ?

That's is both extremely cool and actually rather worrying: might it have 'underpowered' magnets? That would also explain low no load current, actuall!
But measuring it's REAL torque for amp would require a dynamometric stand...

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Re: My RC Mid Drive with Single Stage Reduction

Post by fixvid » Feb 25 2020 10:43am

BalorNG wrote:
Feb 23 2020 4:26am

That's is both extremely cool and actually rather worrying: might it have 'underpowered' magnets? That would also explain low no load current, actuall!
But measuring it's REAL torque for amp would require a dynamometric stand...
Unfortunately i don't have access to a dynamometric stand, but i feel that it has a little more torque at same phase amps than turnigy d5035. I guess it can't be that bad then.

What's more to like about this motor is that it runs cooler than D5035. I remember that turnigy was warming up easily when i was running it hard, but not this one.

I tried a very very steep incline without any leg assist and at 50A phase current it was pulling me up that nasty mountain albeit at very slow speed. It wasn't really cogging only at too low rpms. At 40A phase current there wasn't any cogging at all. At ~15v supply the ESC was pulling around ~25A from the battery but it felt very inneficient because of the low rpms.

I wonder do the cogging disappear with high RPMs and high supply voltage ?

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