Leaf / leafmotor / leafbike high efficiency 1500w motor

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Allex   1 GW

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Allex » May 23 2016 5:59am

I am am thinking about to order a 5t instead for my current 4t for my 18s battery and 60-90amps of power
5t has a tad more copper fill and my main speed spectrum is around 40-60km/h on the trails, wonder if it is worth the swap out?

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Cowardlyduck » May 23 2016 6:12am

Allex wrote:I am am thinking about to order a 5t instead for my current 4t for my 18s battery and 60-90amps of power
5t has a tad more copper fill and my main speed spectrum is around 40-60km/h on the trails, wonder if it is worth the swap out?
I don't see why. Doesn't the extra amps also make more heat on a higher winding...i.e. 60-90A on a 5T will get hotter than 60-90A on a 4T.
Also, unless you need to run a weaker controller, using the controller to limit speed to 40-60kph will do the same thing as running a setup that maxes out at the same speed anyway minus 1-2% total system efficiency for controller switching losses.

The only real advantage to getting a 5T is the better copper fill, but if it just gets hotter because of it (at the same power level) and you have to go slower or stop because of overheating, is it really worth it?
I would only bother with a 5T if you were going to limit amps more TBH.

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Lurkin » May 23 2016 6:33am

Supposedly, >copper fill = >torque...

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Cowardlyduck » May 23 2016 6:58pm

Lurkin wrote:Supposedly, >copper fill = >torque...
Yeah, but so does; > Amps = > torque. Up to the saturation point.

What I'm saying is, what gives greater torque overall, an increase in copper fill, or an increase in the ability to pump more amps for longer.
I'm sure the 5T with it's increased copper fill might perform marginally better at the same amps, but that's not going to be much fun if you can only do it for 5min before overheating.

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by markz » May 23 2016 7:00pm

TeslaNV did a measurement on the MXUS motor. A lower turn count motor could handle way more amperes.

https://endless-sphere.com/forums/viewt ... ps#p944431
MXUS XF40-45H "3000W" Direct Drive Hub Motor Series:

3T:
Max. Continuous Phase Current: 55A
Overheat in 10 Minutes: 85A
Overheat in 60 seconds: 242A

4T:
Max. Continuous Phase Current: 42.6A
Overheat in 10 minutes: 66A
Overheat in 60 seconds: 186A

5T:
Max. Continuous Phase Current: 34.9A
Overheat in 10 minutes: 51.6A
Overheat in 60 seconds: 150A

6T:
Max. Continuous Phase Current: 30.3A
Overheat in 10 minutes: 47A
Overheat in 60 seconds: 132A

Generic Winding Phase Current Limits per strand:
Max. Continuous Phase Current: 2.84A per strand
Overheat in 10 minutes: 4.4A per strand
Overheat in 60 seconds: 12.4A per strand

*All data assumes a non-vented hub motor. Venting or other methods of cooling should increase these values.

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by MLC » May 23 2016 10:51pm

Really great video, CowardlyDuck. That's quite a back yard. Jealous...

Great conversation too. I still get the feeling this conversation tends towards "which is better" (4t vs 5t). It's clear that one is no better than the other. Its all about your application.

If you need much more than 55 kph and don't have the room/budget for high volts, you need the 4t. The OP's app was a long commute at 65+ kph, continuous. The 4t was the better (probably only) choice for him, given his battery at the time (12S LiPo, I think).

(Deleted a flawed paragraph suggesting the 4t stator would have significantly more wasted power (heat) than the 5t stator, at equal speed/torque. This is not the case. See Cyborg entry below.)

A big consideration for me is the exponential increase in required power vs speed (wind resistance). I plan to commute 50+ km so I can't afford to do it very fast (requires much more battery). So, given my range requirements, total weight (135 kg), commute type (mostly<45, with significant stop and go), the 5T with 14S9P battery will provide the best performance, efficiency and range for my application.

Of course I want to play, too (off road, of course!). At top of charge (58 volts) I plan to creep up on 60 kph (with the help of a little wind or a hill) for a thrill. That's crazy fast for me...on a bicycle.

Finally, advice for all, do read this entire thread. Its great. Many of the questions I've seen in the last few pages are answered by knowledgeable people (not like me).

Good luck on all the builds. I'll post a video or pics when I get mine buttoned up.

Best,
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Last edited by MLC on May 24 2016 9:41pm, edited 1 time in total.

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by cycborg » May 24 2016 7:52am

It's sounding like we could use a quick refresher on windings, torque, heating, etc.

First, the bottom line:

For two windings of equal copper fill,
  • both windings will have equal heating at the same torque and RPM.
  • both windings will draw equal battery current at the same torque and RPM.
  • the faster (fewer turns) winding will have a higher top speed for the same battery voltage.
  • if the controller limits battery current but not phase current, both windings will have equal low-speed torque.
  • if the controller limits phase current, then the slower (more turns) winding will have more low-speed torque (unless you can program the phase current to match the winding).
  • the slower wind will be less demanding on the controller and the phase leads.
For a winding with greater copper fill,
  • the motor will generate more torque for the same amount of heating, or less heating for the same amount of torque.
  • the motor will draw less battery current for the same torque and RPM.
  • if copper fill differs only slightly (e.g. 65 vs 64 strands), then the points above regarding equal-fill windings still apply, if you replace "equal" with "nearly equal".
Now some details. First of all, when talking about current, be sure you are clear about whether it's battery current or phase current. We normally talk about battery current since that's easier to measure, but it's phase current that determines torque and resistive loss. The following is about phase current.

Equal copper fill. Suppose you have 64 strands of wire wrapped around a stator tooth, each with a resistance of 100 mOhm, and each is carrying 1 A. These 64 Amp-turns will generate a given flux in the stator, which will result in a given torque in the motor. Furthermore, there is (1 A)^2*(100 mOhm)*64 = 6.4 W of resistive loss.

The torque and loss in this scenario is irrespective of the series-parallel combinations of these wire strands. It doesn't matter if you have 4 turns of 16 parallel strands, or 8 turns of 8 parallel strands, it only matters that each time a strand loops around the tooth, it is carrying 1 A of current.

It looks different from the outside, of course. The 4 x 16 winding will have a resistance of 100*4/16 = 25 mOhm, while the 8 x 8 winding will have a resistance of 100*8/8 = 100 mOhm. For the 4 x 16 winding, the controller will have to provide 16 A so that each of the 16 parallel strands gets 1 A, whereas the 8 X 8 winding only requires 8 A for its 8 parallel strands. But if you calculate I^2*R for these combinations, you'll see they're the same.

Greater copper fill. The 4 x 16 and 8 x 8 are the equal-fill case. Now let's look at the 5 x 13 winding, which wraps 65 strands around a tooth, or 1.5% more copper than the previous cases. Suppose you want the same torque as before, so you still need 64 Amp-turns of current. But now the current is distributed among 65 strands, so the current in each strand is 64/65 A. Now the resistive loss is (64/65 A)^2*(100 mOhm)*65. This works out to the 6.4 W from the previous case, reduced by the factor 64/65.

Remember, this is at the same torque, but the loss is reduced by the ratio of the copper fill.

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Kodin » May 24 2016 2:26pm

THANK YOU for the clarification; I've been saying this for a while, but no one ever listens to me, and there's always more newbies to add comments. The other fun variable is some manufacturers use different size wire for different windings, so some windings can take more current-per-wire before overheating as well.
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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by MLC » May 24 2016 9:25pm

Doh! I was making a basic, goofy mistake. Apologies to everybody! I'll be more careful in future (or just go back to lurking!)
Thanks for all the info Cyborg. You're kind and patient to re-introduce it.
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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Cowardlyduck » May 28 2016 2:36am

Thanks cycborg, that info helps a lot.

One question though, it appears that your calculations above don't factor in the cumulative resistive difference when the stator is heat soaked.

Assuming equal copper mass, wouldn't fewer windings result in a hot stator requiring less amps than to maintain an equal power level?

What I'm getting at is if you compare the resistivity of normal wire when hot it doesn't behave this linearly. Say you have 1M of 12awg carrying 100A vs 2M of 12awg carrying 50A, assuming equal scaling between them, is the total power transfer and heating really the same?

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by cycborg » May 28 2016 9:30am

Cowardlyduck wrote:Assuming equal copper mass...

Say you have 1M of 12awg ... vs 2M of 12awg
Not equal mass!

To make them equal, you would make the 1 m length from two parallel 12 ga strands, so each would carry 50 A. Now, in both cases, you have 2 m of 12 ga carrying 50 A, so the heating is equal.

Alternatively but equivalently, you could use your 2 m of 12 ga in one winding and 1 m of 9 ga in the other, since this doubles the cross-sectional area.

Either way, the resistance of the 1 m length is 1/4 of the 2 m length - one factor of 2 for halving the length and another factor of 2 for doubling the cross-sectional area, so when you double the current in the 1 m length, I^2*R is the same.

So you're generating the same amount of heat, and you're heating the same mass of metal, so temperature rise will be the same, and the change in resistivity will be the same.

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by spinningmagnets » May 28 2016 9:48am

Learning about the physics behind the characteristics of various windings of motors is good, but...Dogman has years of experience actually commuting almost every day, and...there's a reason he likes low-Kv direct drive motors. He likes to ride full-throttle as much as is possible, so he matches the voltage, tire diameter and winding, to end up at his favorite commuting top speed.

Should he use a faster winding and use partial throttle most of the time? Nothing wrong with that. Each choice provides a benefit and drawback. Each one of us has to make a choice about what we want to get, and what we're willing to give up.

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by rb7 » May 28 2016 2:33pm

I am thinking of getting http://www.leafbike.com/products/diy-bi ... t-987.html and i will be using it on the Huffy bike http://www.walmart.com/ip/26-Huffy-Men- ... r/49058110

as per their website they claim top speed of 43mph.... ... Is this correct? To get this speed which battery will i need? I am assuming 48v? how many amps?

I weigh almost 90kg and i will be using it on the road,

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Cowardlyduck » May 28 2016 6:05pm

cycborg wrote: Not equal mass!
Oh yeah, duh! :oops:
Thanks for explaining and not just laughing at a dumb question though. :)
spinningmagnets wrote:Each choice provides a benefit and drawback. Each one of us has to make a choice about what we want to get, and what we're willing to give up.
This is so accurate and true and exactly what I've found also.
Particularly in my case I found that I have a binary throttle...i.e. I seem to go either WOT or I'm braking. Riding like that with anything faster than 50-60kph becomes pretty stupid, so I switched from 66V down to 45V when I moved from my 5T HS4065 to my 4T HS480. Since then I've just stuck with the 4T 12S (45V) combo as it also gives much greater range with my riding style of WOT as much as possible. :)

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Cowardlyduck » Jun 09 2016 6:35am

I decided to add some extra thermal heat shedding capability to my Leaf Motor and since I added Ferro Fluid, it makes more sense to do now.

So I bough 50 of these 25x25mm black heat-sinks for this and other projects:
Image
And a bunch of cheap 1.5mm thick thermal padding
I cut up the thermal padding to match the heat-sinks:
Image

Then stuck them all around the magnet ring and tied them down with some thick string:
Image
It was pretty fiddly/tricky to get all the heat-sinks to stay in place while I tied it all down as the thermal padding doesn't really provide much sticking force and it was a game of catch up for a while until they all stopped falling off. :roll:

However the end result was worth it, looks great and feels pretty solid:
Image
Image
Image

I also added some glue in the only gaps left to lock in the threads and prevent movement:
Image

Given the hottest I was regularly seeing the magnet ring get before was about 75C, I don't expect a huge improvement from just these alone, but combined with the Ferro Fluid, side cover vents and 7 x cooling fans I'm running with, I think only the most extreme use cases will cause me heat problems now. :)

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Allex » Jun 09 2016 6:39am

Fluid with the vented hub? This will not work, you will loose all of the liquid during the first ride.

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Cowardlyduck » Jun 09 2016 6:46am

Allex wrote:Fluid with the vented hub? This will not work, you will loose all of the liquid during the first ride.
It works well actually, and this is the 3rd motor I've done it to.
I've been running Ferro Fluid in my vented Golden Motor on my Recumbent, and my Vented HS4080 (with fans) for some time now without issue.
The key is a balance between the position of the vent holes and the amount of Ferro Fluid meaning the magnets still hold it all in.

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Samd » Jun 09 2016 6:54am

Yeah Justin's did test either then both. But the venting plus ferrofluid wasn't a big jump on ferrofluid alone.


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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by spinningmagnets » Jun 09 2016 7:10am

I am a HUGE fan of Justin's ferrofluid. I am also a fan of ventilation to let excess heat out. But...not both at the same time. It is not because the ferrofluid would be "flung" out of the hub (the magnetic flux should hold the FF in place, yes?), but...ventilation allows grit to enter the interior of the hub.

So...in the world of spinningmagnets...ventilation for race hubs, and....ferrofluid for long-term DD-hub commuters (*the audience applauds wildly as the camera pans the colosseum!).

(I stand ready to accept contrary opinions that provide persuasive arguments...)

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Allex » Jun 09 2016 8:08am

I dont think the fluid will stay there when you drive and bounce around doing offroad, it will constantly move. When I applied the liquid it was very very fluid and went to all kind of places and openings on the stator.

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by neptronix » Jun 09 2016 9:58am

Cowardlyduck, that looks like an awesome setup. I'm really curious as to how far you've increased the continuous sustainable wattage. At 'room temperature' riding ( 70F ), I can easily sustain 2000w indefinitely with my air cooled setup.. you've probably bumped your maximum to 2250-2500..
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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by markz » Jun 09 2016 1:12pm

So I bought 50 of these 25x25mm black heat-sinks for this and other projects:
Cowardlyduck - How much did you spend on those heat sinks?
I found cheaper ones of similar size of Fleabay.

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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by neptronix » Jun 09 2016 1:54pm

The magnet ring on hubs gets incredibly hot.. it might help wick some heat off, as long as the glue you are using transfers some heat to to the aluminum heatsink. Your choice of glue would matter here..
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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by GmagNeato » Jun 09 2016 2:37pm

What about thermally conductive epoxy? And heat sinks that have, or can be given, enough curvature to match the round of the hub, so that there is more natural contact area between the hub surface and actual heatsink backing? And coating the inside of the hub with the right kind of thermal paint should help counter the issue of grit contamination. All of these combined - magnet ring heatsinks, FF, scooped vent holes, and thermal coating inside- would yield great results I would think. Not sure if the thermal coating would somehow interfere with the FF though..
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Re: Leaf / leafmotor / leafbike high efficiency 1500w motor

Post by Cowardlyduck » Jun 09 2016 10:52pm

spinningmagnets wrote:I am a HUGE fan of Justin's ferrofluid. I am also a fan of ventilation to let excess heat out. ...ventilation allows grit to enter the interior of the hub.
Nobody has done any long term testing of this yet, so I'm volunteering to test this myself...on 3 x hubs, 2 with Fans, 1 without. :)
I actually don't think it will be too bad as the spinning holes don't allow very large debris to enter. Yeah the oil will absorb some dust/dirt over time, but how much and how it really effects things is an open question I intend to answer. :)
Allex wrote:I dont think the fluid will stay there when you drive and bounce around doing offroad, it will constantly move. When I applied the liquid it was very very fluid and went to all kind of places and openings on the stator.
I wonder if you've got the same stuff then? As mentioned, I already added FF to my HS4080 and Golden motor also. Been using both these motors for months without issue, and the HS4080 has been through all sorts of off-road, jumps and stairs without loosing any FF so far.
neptronix wrote:Cowardlyduck, that looks like an awesome setup. I'm really curious as to how far you've increased the continuous sustainable wattage. At 'room temperature' riding ( 70F ), I can easily sustain 2000w indefinitely with my air cooled setup.. you've probably bumped your maximum to 2250-2500..
Thanks! I'm curious too...I was already pumping 2.5-3KW sustained through my Leaf with it's existing cooling, so these heat-sinks might give my 3.5-4KW sustained when running my fans. Either way, testing should prove what it really does give me.
eTrike wrote:Maybe CD can give us some good test data since his fan teating data was so well documented.
I'll try! Time is always the problem for me...maybe the next tests will just be in my backyard. :lol:
markz wrote:Cowardlyduck - How much did you spend on those heat sinks?
I found cheaper ones of similar size of Fleabay.
Yeah they weren't the cheapest at $20 USD for 50, but I needed 25x25mm and wanted black, so that was why I went with those.
neptronix wrote:Your choice of glue would matter here..
I just used thermal pads to make it easier/simpler, but thermal epoxy would be better I agree.
GmagNeato wrote:What about thermally conductive epoxy? And heat sinks that have, or can be given, enough curvature to match the round of the hub, so that there is more natural contact area between the hub surface and actual heatsink backing? And coating the inside of the hub with the right kind of thermal paint should help counter the issue of grit contamination. All of these combined - magnet ring heatsinks, FF, scooped vent holes, and thermal coating inside- would yield great results I would think. Not sure if the thermal coating would somehow interfere with the FF though..
Yeah, that would all be nice, but a lot of effort.
The reason I used small 25x25mm heat-sinks and 1.5mm thick thermal padding was to assist in not having to worry so much about the curvature as the padding takes up most of the gap under each end of the sink.

Cheers
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For Sale:
Custom made 18650/21700 battery packs - Australia only
High Power LiPo wiring harnesses - 4P - XT90, HXT4mm, 5.5mm. 200Amp+ capable. Global shipping.

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