GNG, 1000W 48V BB-drive, $400

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Denisesewa   100 W

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Re: GNG, 1000W 48V BB-drive, $400

Post by Denisesewa » Dec 09 2012 9:59pm

spinningmagnets wrote:
65T - 12T, #25 chain
bzhwindtalker is currently trying out his primary drive with #219 chain using 60T - 11T sprockets, 14S LiPo (49V-58V) on a 24-inch rear wheel.
http://endless-sphere.com/forums/viewto ... 45#p674387
Yes I know, but he did mention the #25 chain combo on page 51. when I showed a picture of the sprocket I ordered.
I also run a 24 wheel and 14s 2p lipo

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spinningmagnets   100 GW

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Re: GNG, 1000W 48V BB-drive, $400

Post by spinningmagnets » Dec 09 2012 10:25pm

Thanks! I was just listing the working options for the readers, ones that performed well so all the choices were posted near each other.

I appreciate the pics you posted, and I am looking forward to the final results.

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christerljung   100 W

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Re: GNG, 1000W 48V BB-drive, $400

Post by christerljung » Dec 10 2012 3:56am

@denizewa: I made one little dimple with a drill in the motorshaft, which one of the setscrews could dig into. Since i run this on 72v with hard accelleration and high offroad load it seem to work very well.

@crossbreak: Is it plain resistance without power and no rotation? I can do that later today.

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Re: GNG, 1000W 48V BB-drive, $400

Post by crossbreak » Dec 10 2012 8:28am

Great! I made a short vid to show how to measure the phase resistance. You dont need a lab PSU, just one that outputs 3Volts max and many amps (not too many). One that outputs only 1Volt would be perfect.

Measure both current and voltage, phase resistance is voltage/amps. Vid: http://www.youtube.com/watch?v=HT-hEMGK ... e=youtu.be

Guess the phase resistance is not less than 150 mOhms, so if you push in 3Volts you should see about 20amps. That is okay for this motor if you dont do it too long.

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christerljung   100 W

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Re: GNG, 1000W 48V BB-drive, $400

Post by christerljung » Dec 10 2012 12:54pm

Some facts to the wiki, of our beloved GNG:s

DC phase resistance @ 184.3 mV, 2.52 A:
73.134 milliohm

Stator thickness: 24.7mm
50 laminations
lamination thickness: 0.494mm

12 poles
copper wire diameter 0.7mm

magnet rotor
8 magnets
50 laminations
lamination thickness: 0.494mm

Inner bearing: 6201RS
Pulley bearing: 6203RS

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crossbreak   100 MW

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Re: GNG, 1000W 48V BB-drive, $400

Post by crossbreak » Dec 10 2012 12:57pm

thanks so much christerl! we have waited so long for someone to post this!

Maybe you have some pics from the inside now? i'm waiting keen to see some ;)

You can access the new wiki page here: http://endless-sphere.com/w/index.php?t ... s_Middrive

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christerljung   100 W

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Re: GNG, 1000W 48V BB-drive, $400

Post by christerljung » Dec 10 2012 1:05pm

The heart of the GNG, split up:
Image

Image

Image

Image

Image

Image

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Image

Image

Image

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crossbreak   100 MW

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Re: GNG, 1000W 48V BB-drive, $400

Post by crossbreak » Dec 10 2012 1:10pm

This is far beyond my expectation. Seems like this is a true 2kw motor, no doubt. I like the pic in which we can watch you test the magnets :D Seem like it would like more speeeeeeeeeeeeeeeeeed!

Now we now why this one has 100Watts no load consumption :D i'm waiting keen for miles next post here ;)

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christerljung   100 W

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Re: GNG, 1000W 48V BB-drive, $400

Post by christerljung » Dec 10 2012 1:25pm

Indeed yes! :mrgreen:
I had to use help from some tools to manage pulling the rotor out of the stator because of the powerful magnets. :twisted:
Next i will put the shaft in the lathe and give it some precisionwork for the perfect pulley fit. Then try a 12/72 first gearing with 24S 88V nominal. And winter spike tyres.
Last edited by christerljung on Dec 10 2012 1:38pm, edited 1 time in total.

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Miles   100 GW

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Re: GNG, 1000W 48V BB-drive, $400

Post by Miles » Dec 10 2012 1:28pm

Thanks for the pics Christer.

Please could you measure the magnet thickness? Thanks

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christerljung   100 W

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Re: GNG, 1000W 48V BB-drive, $400

Post by christerljung » Dec 10 2012 1:50pm

sure Miles, no problem:
Magnet thickness: 4.2 mm
Magnet size 24.5 X 24mm


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Miles   100 GW

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Re: GNG, 1000W 48V BB-drive, $400

Post by Miles » Dec 10 2012 1:54pm

GNG motor data:

Weight?
12 slots 8 poles
Winding factor 0.866
Cogging: 24 step per rev.
Rm 73 milliohms (phase to phase)
Kv 67 rpm/V
Kt 0.143 Nm/A
Km 0.53 Nm/√W
Specific Km ?

Rotor OD ?
Stator OD ?
Stator ID ?
Stator thickness 25mm
Lamination thickness 0.5mm
Magnet thickness 4.2mm

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circuit   100 kW

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Re: GNG, 1000W 48V BB-drive, $400

Post by circuit » Dec 10 2012 2:02pm

crossbreak wrote:Now we now why this one has 100Watts no load consumption :D i'm waiting keen for miles next post here ;)
One difference I can see is it's rotor is made from lamination, not a solid peace.

BTW, anyone tried to peal off a nickel foil off a neo magnet and measure it's electrical conductivity? Maybe all the eddy current losses are not in magnets, but in rotor?
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crossbreak   100 MW

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Re: GNG, 1000W 48V BB-drive, $400

Post by crossbreak » Dec 10 2012 2:08pm

circuit wrote:...Maybe all the eddy current losses are not in magnets, but in rotor?
the magnet path in the stator is much longer than the one in the rotor. If they use the same laminations, major eddy current loss occurs in the stator.

Edit: OK you think about the magnets... their section is tiny compared to the rest :? guess they have no big influence

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Miles   100 GW

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Re: GNG, 1000W 48V BB-drive, $400

Post by Miles » Dec 10 2012 2:12pm

http://www.ndfeb-info.com/characteristics.aspx

The laminations are just a constructional thing - see the magnet retaining method etc.

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Re: GNG, 1000W 48V BB-drive, $400

Post by crossbreak » Dec 10 2012 3:02pm

christerl, the GNG looks like it is made for 3000rpm. So there is n sense in using more than 20s lipo, should only get inefficient at higher speeds :?

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christerljung   100 W

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Re: GNG, 1000W 48V BB-drive, $400

Post by christerljung » Dec 10 2012 3:30pm

Yeah. Maybe thats something i allready feel, it kind of fades in accelleration at higher rmpm:s when run on 18S. Or is it just the different characteristics of an electric motor vs a combustion engine? The GNG has really got the bottom end grunt thats for sure, thats also the main reason for eating belts.
-Miles, ill be back tomrrow with more measurements.

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Re: GNG, 1000W 48V BB-drive, $400

Post by crossbreak » Dec 10 2012 3:36pm

the only reason i can see it eats belt is the tiny 14T sprocket. If it would was 18T there would be half the problem.
christerljung wrote:... i allready feel, it kind of fades in accelleration at higher rmpm:s when run on 18S. Or is it just the different characteristics of an electric motor vs a combustion engine? ...
it depends on how your phase current is set and if you drive at pedal speeds or not - even if there is no recognizable eddy current braking (like engine brake, but it can not be really "felt" cause there are the freewheels in the drive). what batt and phase current have you set?
Last edited by crossbreak on Dec 10 2012 4:26pm, edited 2 times in total.

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Miles   100 GW

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Re: GNG, 1000W 48V BB-drive, $400

Post by Miles » Dec 10 2012 3:38pm

christerljung wrote:-Miles, ill be back tomrrow with more measurements.
Great. Thanks for the magnet dimensions.

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Re: GNG, 1000W 48V BB-drive, $400

Post by bzhwindtalker » Dec 10 2012 3:46pm

Thanks for those pics Christer. I like this motor a lot! Built to last, good thermal path, strong axle. Now I want to put one in my dirt mtb too ;)
The external case looks quite a lot like the original Kollmorgen motor.

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Denisesewa   100 W

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Re: GNG, 1000W 48V BB-drive, $400

Post by Denisesewa » Dec 10 2012 9:26pm

I got the chain drive set up today, first thing was to indicate the sprocket for runout , I found the sprocket itself is not exactly round but the final runout is a hell of alot better than the original pulley.

Image

Had to go with a half link for the chain but it worked out ok, then I fabricated a chain tensioner to take up slack as the chain stretches,


Image
the chain length is perfect as it is and after spinning it up with and without the tensioner I couldnt believe how much power a lightly sprung tensioner robs from this thing.
All in all pretty happy with the conversion. :D

Image

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parajared   10 kW

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Re: GNG, 1000W 48V BB-drive, $400

Post by parajared » Dec 10 2012 9:42pm

Neat stuff,
I want to do one!
Can you post a parts list so I can order the same parts?
How do you get the little sprocket off so you can put your 12t sprocket on?

Maybe I will just use the existing gearing on the GNG and drill holes then bolt into it.

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Denisesewa   100 W

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Re: GNG, 1000W 48V BB-drive, $400

Post by Denisesewa » Dec 10 2012 10:13pm

parajared wrote:Neat stuff,
I want to do one!
Can you post a parts list so I can order the same parts?
How do you get the little sprocket off so you can put your 12t sprocket on?

Maybe I will just use the existing gearing on the GNG and drill holes then bolt into it.

If you go back a page or two I showed how to turn the shaft down, click on the pic for the video, I used the original large belt pulley and trimmed the outer edge off then drilled and bolted the sprocket on, the parts are from TNCscooters.com , # spk-103240 for the 65 tooth , #spk-106012 for the drive sprocket , and 2 ft of # chn-105250 chain , you will have to find another supplier for a #25 halflink , the tensioner was made from an old dirt bike chain roller cut down ,the spring from the original secondary drive tensioner which isnt needed there and scraps of aluminum.

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parajared   10 kW

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Re: GNG, 1000W 48V BB-drive, $400

Post by parajared » Dec 10 2012 11:17pm

Ok,
I am going to try to copy Denisesewa's method.

I am going to try the 13t sprocket instead of the 12t to try and avoid the half link problem. I am going to attempt to use a 7 tooth pinon gear paired maybe to a rollerblade bearing as a chain tensioner. I saw the video, and I am going to try the file down technique like Denisesewa and Christlerjung did.

Total price shipped only $37.45 USD.
since the stock driven 44T chainring has five arms, it may be a simple job to drill 5 holes in them at a 130-BCD pattern to attach a larger chainring. Vuelta has these at 48T-60T (if your frame/chainstays/ground-clearance will allow a larger chainring). There are also 48T-50T in a 5-arm 110-BCD chainring. http://www.vueltausa.com/se-chain-ring- ... 60t-1.html

edit: the stock chainring that drives the chain from the BB back to the rear wheel is a 38T, perhaps it may be useful to put the 44T in that spot, and then attach a 60T to the 38T that you now place in the motor-driven position. This would lower the pedal-cadence some, and still keep the top-speed near stock. This would make the secondary drive ratio 12T / 60T = 5:1, the overall reduction would then be 5.7:1 X 5.0:1 = 28.5:1 ...The original ratio is 21.1:1, the 155 pedal cadence should then come down to somewhere around 110?...
I may also try spinningmagnets' suggestion of using a 60t chainring with the idea of stopping and manually moving the chain with my fingers for a dirt/highway setup
Last edited by parajared on Dec 11 2012 12:01am, edited 2 times in total.

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