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GNG, 1000W 48V BB-drive, $400
- Thread starter spinningmagnets
- Start date
ebiker1
100 mW
Miles said:
good question, but can you finish the answer? OK, newb and poor typist here. i know enough to understand the question, not enuf to complete the answer. and maybe not enuf to figure it out after you complete it. but i will figure it out. i'm starting to build one of these kits and was looking up sensored vs sensorless and found this. takes time to figure some of the basics.
So, it's Amps which count. You can increase the voltage and hence the speed to get more power output but you can't increase the current to get a similar power by increasing the torque.
Putting it another way, the maximum torque output is always proportional to the size of a motor but the maximum power output is only limited by its mechanical integrity or possibly the point where parasitic losses become overwhelming.
Putting it another way, the maximum torque output is always proportional to the size of a motor but the maximum power output is only limited by its mechanical integrity or possibly the point where parasitic losses become overwhelming.
wavezz2k
100 mW
Miles.
You may be an expert, but as a research engineer at a leading US Postgraduate School in the aero department, the above statement doesn't seem to help my understanding. With further preamble, there's a ton of battery packs of every size imaginable in the department next door that does UAS unmanned autonomous systems, i.e., Predator, surface and submersible types, Serious, not one but two Predators. Those guys are definitely expert, but I prefer not to bug them with my retarded hobby questions (EV bikes, multirotors, the like). They don't ask me about satellites, either.
I got. "the loss goes up with the square of current", cool with that. So to get comparable power, it's going to require disproportionately greater amps, it would be better to regear the reduction side, keep with the higher volts and lower amps - that's my take away if I follow the sparky point. The motor leads (nor motor?) likely aren't gonna like 50amp, right?
As a side note, an LFP at storage volts, 39.5v will not light up the stock GNG controller on my bench. So to play the volts game outside of 48-60v requires another controller. .. time to read the sensorless thread on the GNG - Snellimin, @http://www.endless-sphere.com/forums/viewtopic.php?f=28&t=44701
Radical, This forum is rather awesome...
wavezz,
I'm no expert. I do my best but I've no technical background... I've had to teach myself this stuff.
There is a limit to the amount of torque a motor can produce which is set by its ability to dissipate the heat generated. The losses in the windings of the motor follow I²R. Torque is directly proportionate to phase current. The amount of torque generated for a given current depends on the field strength of the magnetic circuit and the number of turns in the motor windings. The relationship between current and torque is the motors torque constant (Kt). If you rewind a motor with a greater number of turns, it will generate more torque per Amp but in order to fit in an increased number of turns the cross sectional area of the wire needs to be reduced and, of course, it will also get longer... So, you can vary Kt but the greater resistance from increasing the number of turns balances the increase in torque per Amp and so the amount of heat generated for a given torque output remains the same (unless you can pack more copper in the motor slots).
Ok, so far?
I'm no expert. I do my best but I've no technical background... I've had to teach myself this stuff.
There is a limit to the amount of torque a motor can produce which is set by its ability to dissipate the heat generated. The losses in the windings of the motor follow I²R. Torque is directly proportionate to phase current. The amount of torque generated for a given current depends on the field strength of the magnetic circuit and the number of turns in the motor windings. The relationship between current and torque is the motors torque constant (Kt). If you rewind a motor with a greater number of turns, it will generate more torque per Amp but in order to fit in an increased number of turns the cross sectional area of the wire needs to be reduced and, of course, it will also get longer... So, you can vary Kt but the greater resistance from increasing the number of turns balances the increase in torque per Amp and so the amount of heat generated for a given torque output remains the same (unless you can pack more copper in the motor slots).
Ok, so far?
RustySpokes
10 µW
RustySpokes said:I ordered the 36V/350W version yesterday and received the set of pics of my order all packed up a few hours later
One question, I'm planning to run this with 12s worth of LiPos, but the voltage range doesn't quite line up with 36v - am I likely to have problems with the controller?
Hmm. It seems not many have ordered the 36v version?
Mine arrived this morning - ordered Monday after lunch, arrives Wednesday morning, pretty decent postage service.
I asked Jon what the max and min voltages were for the controller. He replied with 37.5v and 36v respectively. I'm not entirely convinced he knows what he's talking about. I tried out the controller and motor on the bench power supply and found that the controller drops out at 28.5v. Ran fine up to 50v, so should be OK on a 12s pack (not sure what the limiting factor is here - the rating of the caps?).
Had a few dramas dismantling the BB of my rather decrepit mountain bike. Really should have done a bit of Googling before removing it, would have saved a lot of swearing, followed by the grinder, the punch, a lot of bashing and finally the MIG welder trying to remove a left-hand thread the wrong way
Clearly I'm not much of a bike nerd 
fabiograssi
100 W
Please, a good soul can indicate a good model/brand (and the source where to get) additional belts for this kit?
- Fabio
- Fabio
fabiograssi
100 W
snellemin said:
Some kind of code/model?
ebiker1
100 mW
wow! great info, thanks for the expanded explanations.
fabiograssi
100 W
neptronix: I didn't put my kit in action yet... But I think a replacement belt is a must in this kit, hum?
- Fabio
- Fabio
redstone02
100 W
- Joined
- Aug 1, 2012
- Messages
- 102
Mine bike/GNG came together this past weekend. My set-up is a commuter bike w/no steep inclines.fabiograssi said:
On bike trail to work, with wind to my back, got 32 mph.
Examined belt after 10 miles, looked good... but 10 miles is nothing.
There was wear from the idler.
I'm looking at removing the idler, just got to figure out belt size w/o idler.
Maybe a good idea = keep a spare belt and needed tools in bike rear rack.
fabiograssi
100 W
May be wrong, but I think we just allen wrench to change the belt... protection plate and tensioner!
redstone02
100 W
- Joined
- Aug 1, 2012
- Messages
- 102
IIRC = 5mm allen wrench is all it takes.fabiograssi said:
Cyclebutt
100 W
@ snellmin: I'm going to avoid using a left side throttle for now, want to offer eBike kit installation services, gotta stay with midstream, ergonomics. Good to know that option is available, wasn't aware. Thanks!
@ wavezz2k: Tried that with the throttle position, my up-shift lever hits the twist-throttle housing when mounted in what would normally be the ideal position, possibly a different trigger shifter or a thumb index would work better.
@Rustyspokes & LI-ghtcycle : The GNG controller has two white wires designated as "learning mode" connections that are only used when first hooked up to battery pack. I'm wondering if the controller can sense the difference between 36V and 48V? Is this possible? Has anyone tried this? I went with 48V when I first got into eBikes (just last winter) because there are so many options available. 72Volts seems to be the experimenters haven for now, will explore that later. Gotta pay the bills first. OUCH! (just did a mental calculation of my eBike investment-to-date, HA!)
@ wavezz2k: Tried that with the throttle position, my up-shift lever hits the twist-throttle housing when mounted in what would normally be the ideal position, possibly a different trigger shifter or a thumb index would work better.
@Rustyspokes & LI-ghtcycle : The GNG controller has two white wires designated as "learning mode" connections that are only used when first hooked up to battery pack. I'm wondering if the controller can sense the difference between 36V and 48V? Is this possible? Has anyone tried this? I went with 48V when I first got into eBikes (just last winter) because there are so many options available. 72Volts seems to be the experimenters haven for now, will explore that later. Gotta pay the bills first. OUCH!
(just did a mental calculation of my eBike investment-to-date, HA!)melodious
100 kW
Nice find on the document about "belt fatigue/failure possibilities". I've read a similar type of document applying to chains. There is alot of information you can learn from them. And knowing in advance what your belt and/or chain is doing gives you good assessment skills to fix future problems that may arise. The person who is thinking about taking out the idler to get a good initial fit for the belt may have problems down the future as the belt stretches. 
redstone02
100 W
- Joined
- Aug 1, 2012
- Messages
- 102
melodious said:Nice find on the document about "belt fatigue/failure possibilities". I've read a similar type of document applying to chains. There is alot of information you can learn from them. And knowing in advance what your belt and/or chain is doing gives you good assessment skills to fix future problems that may arise. The person who is thinking about taking out the idler to get a good initial fit for the belt may have problems down the future as the belt stretches.
Could be; the idler on my kit does not "float", it is fixed and bolted in place. Are there kits with spring loaded idler?
The belt shouldn't stretch by any appreciable amount. I expect the small diameter idler is the cause of the premature failures but I doubt if simply removing it is a cure. This kit was designed by an idiot, or a cynic.melodious said:The person who is thinking about taking out the idler to get a good initial fit for the belt may have problems down the future as the belt stretches.
crossbreak
1 MW
Agreed, the idle heat production and belt slippage are not the only signs for this, but the only way I see to fit a durable transmission into the given build space - while maintaining the reduction ratio - is using a chain IMO. An 11T to 60T 6mm chain drive would get at least close to this. Maybe not the best solution but a practicable one.
wavezz2k
100 mW
Don't laugh too hard, LoL- found the 8spd hub was stuck because underside GNG throttle ring was in the way (even with rotating 'up') - truly, DOH! moment.
Twist shifters, reference 3,7,8, & 9 spd options -
http://www.amazon.com/s/ref=nb_sb_noss_2?url=search-alias%3Daps&field-keywords=SRAM+twist+shift
Prefer to have a reverse throw shifter mounted left side, than a left handed throttle, IMHO.
There are several SRAM twist shifters that can swap out for the push button fire. I found a direct swap out for mine for $10, ordered.
Rather than move throttle to the left gonna move the twist shift to the left (just me, can't do left throttle, too many motorcycle hours).
Plus up, add the three speed Lymen function on a thumb switch on the right. Layout is then 8-spd left twist, 3spd right thumb slide, w/ throttle twist on the right in the correct orientation. Waiting now for 80v Lyen 6FET sensorless, couple more batteries to up -volt...
With Lymen 3 spd, even an old school 3 speed itnernal hub would give a 9 spd type setup. Likely work great.. maybe try to find a old schwinn beach cruiser with a 3 spd, that'd be retro.
Geared reduction:
Reduction drive noting several these past few posts, focus on the reduction side (again). Several earlier posts with a cool idea of using a large helical gear set (composite)- it was for large R/C helis. Gas scooter chain likely not enough room. Perhaps other ideas? Issue still resides also that the drive pulley is married to the motor (can't be pulled), and may require a kook adapter, no matter which drive upgrade gets implemented... kinda nuisance.
View attachment 1
Bro ..is the gng motor can use the crystallye controller ? if the contoller is 48v 45a with sensor ?
parajared
10 kW
caijunze: are you using the smaller belt to get around having to use the belt tensioner, or did you just forget to attach your tensioner?
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