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

[bzhwindtalker]

For those wondering how i'ts done :



The pulley is secured with a key and a 17mm nyloc nut. I got it off quite easy, no ned for an extractor.
The steel core seem to be press- fitted into the cast aluminium pulley.
I did not yet secure the chain sprocket to the motor as I have ordered two more belts including a 450mm one to test in the BZH style
First belt did 12 hours, second one 4h. No one has documented the use of the 450mm one yet?

 

[christerljung]

bzh: Nice idea about lazercut big sprocket adapter. From the experience of the simple eyefit mounting in my setup, it is the most critical part. Mine was about 1.5mm offset when rotating the big sprocket. It might doesnt sound that much but actually it forces me to use an extra link on the chain. The small sprocket also wobbling a bit but it doesnt affect the chain at all.
I beleive center steel part of 80 tooth wheel is threaded, not pressfit. It looks very likely to be the same as the 80 toothed wheel in this list:
http://www.electricscooterparts.com/beltcogs.html
Good luck with the belttesting, keep us updated.

 

[gestalt]

I was thinking about ways to protect the GNG from water and crud and figured you would also want to have some protection for the controller as well. So why not have the controller mounted to the same bracket as the motor and reduction? That would keep it all inside one enclosure and keep all the wires nice and short as well.

Do you think there would be issues with vibration or EMF interference being so close to the motor? A nice thick slab of rubber between the bracket and the controller might help out with vibration.

 

[neptronix]

Damn Christerljun; you might as well be manufacturing these kits while you're at it :lol:

These kits seem to require too much modification.
Maybe it is time to make something like the GNG kit? especially if some of you can make the custom plates

http://www.thesuperkids.com/10wabmcbrels.html

How about this motor...

http://www.thesuperkids.com/curhitmot.html

Or this motor... sandwiched between two BB mounted plates, much like the GNG?

The MAC versions of these motors can be had for around $100-$150.

You'd need a few stages of reduction, but they could be done with #25 chain..

The small MAC motor ( 300-600W ) is about 1.5kg and the larger MAC motor ( 600-1000W )is about 3kg.

I don't mean to derail this thread into another topic, but it looks like you guys are basically reinventing this kit already, so it's something to consider.

 

[spinningmagnets]

The second 400W motor looks like the Kollmorgen, if it is, the affordable ferrite magnets are not very strong.

The first motor ($250) looks promising. Any one know the dimensions, the weight, and most importantly the kV?

Also, I recently noticed where a Hobby-King 80-100 was re-terminated from Delta to Wye, and it changed the kV approximately in half. Some motors might be a good fit if they were easy to re-terminate?

 

[crossbreak]

Mine was about 1.5mm offset when rotating the big sprocket. It might doesnt sound that much but actually it forces me to use an extra link on the chain.

If you work more accurate you will get about 0.5mm misalignment. You just have to follow the rules of good alignment, like using a good circle and drills. Bad one from your local store may suck. I got the best result when I used cheap industry stuff from the net. This is cheap in germany (since this is bought the most here), but it should be affordable in other countries as well. The cheap stuff in your local store is just for drilling hopes anywhere.. Did not remind that when I was at my local market last time and bought a well looking drill set . It drills holes, but the drill float anywhere if drilling holes deeper than maybe 2mm. Cost me $8. I would have better burned the money.

You know i'm a person who test motors. I re-terminated 3 motors. Sold all of them after (bought them mostly to try). Did not loose money by that (i hope at least ) It was all the same on all three motors and took me about half an hour. The 80-100 was the one which was hardest (my first one actually) since it was most work to assemble. All of the turnigy motors I know are delta. So the mod can be done on all of them. This still does not give the options I would like.

The $250 motor looks most promising IMO. But I am not ceratin if it is more powerfull thatn a bafang 500W. the bafang is larger in dia (160mm to 125mm) and it has only 20poles if my intel is right.

 

[rodgah]

just if anyone is interested.....found this....

http://www.electricscooterparts.com/beltcogs.html

says they are a threaded internal....with the same thread as a freewheel! Im sure I have seen #25 sprockets that thread onto a hub body :wink:

whats even more interesting is this.....

or this..

which allow you to go up more teeth on the motor and keep the same reduction and handle more power.

Rodger

 

[bzhwindtalker]

Nice find... Using the 95t one would allow to run 18t on the motor. I don't know if it would help a lot, but if you can run 20mm belts it would do the trick I guess!
I changed my BB for a 131mm one, I had to remove the center part of the FW cranks to make it fit, so I don't have a support bearing anymore... That's how Cyclone has been doing it for years so it should work. I did not have problems with that on my last hub mid-drive. I will try to make a bash plate out of plastic.

 

[t3sla]

Stock spring lasted all but five minutes of a test ride dam tension element is poooooor

 

[Cyclebutt]

The first thing I changed. Spring.

 

[parajared]

I tossed that spring from the get-go and bungee corded mine.

 

[Rassy]

Yep, tossed the spring, applied some light tension by hand, tightened the screw. It did back off once, so adding a zip tie seems like a good plan. Thanks for the idea.

 

[snellemin]

Am I the only one that doesn't have a problem with the stock spring?

 

[t3sla]

Yes
Seriously at a loss to how that hasn't failed on you, need to upgrade mine to a high tensile one...

 

[christerljung]

My first GNG got a perfect working tensioner with original spring. But the second i bought for the commuter works really bad. I have noticed they changed the spring on this. A factory downgrade

 

[d8veh]

Am I the only one that doesn't have a problem with the stock spring?

No. I've made no modifications to mine at all, and it runs perfectly.

 

[t3sla]

Testing at 36V lasted 10 minuets :|
Upgraded to 72V (12FET lyen, no current limit) and started freaking out cars
Lasted another 10 minutes before I stripped the drive belt

Back to 48V once I get a new belt :wink:

This thing is cheap DIY fun, dad and I have enjoyed tinkering it's been worth it for that alone

Will get really need to scale back to 48V and some current limit, really think it was the stop starts at destroyed it....Hmmm maybe FT is onto something with his lagging controller

 

[neptronix]

It's the low end torque that kills these gears / chain and belts. I bet the standard controller isn't tuned for a proper battery to phase amp ratio. I'll share you a little trick that saved the planetary reduction gears in hub motors before we had those fancy composite gears ..

If you have a lyen/infineon controller, the default phase amp to battery ratio is something like 3:1, or 60 amp phase to 20 amp battery, for example.

This allows you to put out really fantastic low end torque from a stall, but it does produce a very large peak of torque, as you know electric motors are characteristically capable of producing.

If you dial back the phase amp to battery amp ratio to say, 2.5:1, the low end torque will be much less intense, but the mid-high torque will be just the same. Venture into 2:1 ratios and you will see in some motors - torque actually being really low from 0rpm, and gradually ramping up, much like an internal combustion engine where all your torque is made near the RPM limit of the motor.

Give it a shot guys. I bet your springs and belts will last longer if you do this. It will be less exciting, it will be harder to do a wheelie, but the kit should last a lot longer.

 

[t3sla]

yeah thanks for that, sadly my usb/serial cable is still in the mail.....

I wanted to get it stable at 72V then move to 48V, I did manage to do all of that but not in time

The best way I could describe the throttle was tan(x), stupid


Can anyone explain the force issues with having the tension element being really stiff

 

[Velcro01]

If you have a lyen/infineon controller, the default phase amp to battery ratio is something like 3:1, or 60 amp phase to 20 amp battery, for example.

Hi neptronix, could you, or someone else please explain this to me. How can you have more current in a phase compared to what you are drawing out of your battery?
Sorry for the slightly OT question here... :?

 

[neptronix]

If you have a lyen/infineon controller, the default phase amp to battery ratio is something like 3:1, or 60 amp phase to 20 amp battery, for example.

Hi neptronix, could you, or someone else please explain this to me. How can you have more current in a phase compared to what you are drawing out of your battery?
Sorry for the slightly OT question here... :?

Oooh, that's a hard one to explain properly. I think Miles or Liveforphysics explained it to me at one point, but i forgot exactly how they said it, so here's my butchered version.. and if they chime in, listen to them and not me :lol:

Basically your controller is able to dish out a multiple of your battery current at lower to mid RPMs by converting a high voltage into a lower voltage w/higher amperage internally ( this isn't exactly how it does it, but the effect is the same ). This helps you get started from a stop much easier, and also gives you some more power when climbing hills so that the motor doesn't stall out. This is more useful for lower power motors ( like 250w geared motors - 750w DD hubs ) than it is for high power motors where you might be producing 200nm/170ft-lb from a stall, which is certainly good enough :lol:

So let me illustrate this with a motor + controller + battery combination that turns at a maximum of 400rpm under load.
And let's say that you have your battery amp / phase amp set like this: 20A / 60A

At 0RPM, the motor is having 60A pushed into it.
at 100RPM, the motor is having 50A pushed into it.
at 200rpm, the motor is having 40A pushed into it.
at 300rpm, the motor is having 30A pushed into it.
at 400rpm, the motor is having 20A pushed into it.

The above picture is a fairly typical DC motor response curve.
If we use a 3:1 phase amp to battery ratio, we are getting a response similar to this.

But if we use a lower ratio, like 2:1, those amps look like this:

At 0rpm, the motor gets 40A.
at 100rpm, the motor gets 35A.
at 200rpm, the motor gets 30A.
at 300rpm, the motor gets 25A.
at 400rpm, the motor gets 20A.

And the torque at 0RPM is 33% lower, at mid-speed, you get a little bit less power, but at full speed you get the same power. This is not a big problem because you spend most of your time around full speed in a mid drive system. But you will have to be more careful about being in the correct gear when you are climbing hills, because at lower RPM, the torque will not be as high.

Here's the thing about gears, belts and chain. They can handle more torque the faster they spin. That's fine if you have an internal combustion engine, but you have to oversize things for electric power due to the low end torque

I think that GNG really undersized things here. This keeps the cost down and the weight down, but i think most of you want a mid drive system that lasts more than a few miles, right?

Anyway, tuning down the phase:battery amp ratio should help. Maybe it can be reliable on stock power if you lower the initial torque that way.

 

[Cyclebutt]

It's the low end torque that kills these gears / chain and belts. I bet the standard controller isn't tuned for a proper battery to phase amp ratio. I'll share you a little trick that saved the planetary reduction gears in hub motors before we had those fancy composite gears ..

If you have a lyen/infineon controller, the default phase amp to battery ratio is something like 3:1, or 60 amp phase to 20 amp battery, for example.

This allows you to put out really fantastic low end torque from a stall, but it does produce a very large peak of torque, as you know electric motors are characteristically capable of producing.

If you dial back the phase amp to battery amp ratio to say, 2.5:1, the low end torque will be much less intense, but the mid-high torque will be just the same. Venture into 2:1 ratios and you will see in some motors - torque actually being really low from 0rpm, and gradually ramping up, much like an internal combustion engine where all your torque is made near the RPM limit of the motor.

Give it a shot guys. I bet your springs and belts will last longer if you do this. It will be less exciting, it will be harder to do a wheelie, but the kit should last a lot longer.

Okay, I'm sold. But, I don't have a Lyen/Infineon controller (These are both programmable?), just this little deal from GNG. Let's say I want to go with the a phase amp to battery ratio of around 2.25:1 to 2:1 region. Is there a resistor or circuit I can modify/add to my existing controller to change it from the (assumed for this controller?) default of 3:1? and still get full performance at the top RPMs?
Also, don't the Lyen controllers have throttle lag issues as well? Seems I saw that in another thread, one of my complaints about the stock controller/throttle/motor set-up.

 

[christerljung]

The GNG belt to chain conversion is almost ready for a testride. Unfortunately i need new liops after i almost burned down my house on thursday night. Dont charge lipos unsupervised. Mine caught fire when me being a fool, just forgotten them at bulkcharging 5A, no protection
Anyway here is a little video showing the chain reduction in action. Sorry for bad focus, dont know what happened with the camera.
The trickiest part of this conversion was the chaintensioner. Very hard to get it in the exact position. I had a much more fancy looking rotating spring for the tensioner(instead of the rubber band), but i just couldnt manage to get in correct position.

[youtube]uXS0Ix-Arbc[/youtube]

 

[iperov]

GNG origin: from china $156 http://www.mistertao.com/taobao-products/taobao-item-18826436986.html

 

[Thud]

Damn....at that price point, this kit is practicly unbeatable.
I can crush the quality, but nowhere near that price......
I may just order one now...... :?