Rewinding a 15470 outrunner

Electric Motors and Controllers
trialspower2   10 W

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Rewinding a 15470 outrunner

Post by trialspower2 » Jan 07 2022 9:43am

Hello,

I have a couple of bikes, one with a 120100 50KV outrunner and the other with a 15470 27KV outrunner. After taking the gearing into account, both bikes have a top speed of around 40mph.

I was expecting that the 15470 would have slightly better performance. However this is definately not the case. The 15470 is massively struggling to make enough torque off the line and just does not demand the same amount of current per duty cycle as the 120100.

I am putting this down to the low KV, I think that the stator is saturating, expecting alot of bottom end torque off a low KV motor seems a bad idea, higher KV with more gear reduction seems better. So my intention is to rewind the 15470 for 50KV for a direct comparison between the motors.

I was wondering if anyone on here has undertaken the task of rewinding a 15470 and can offer any details/ advice before I start the process. My intention is to get wire that is double the thickness of the current and do half as many turns. But I am wondering how the motor is wired and what the gains would be from putting more copper into it etc.

Cheers
Danny

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Re: Rewinding a 15470 outrunner

Post by SafeDiscDancing » Jan 07 2022 10:26am

My motor threw a wire and fried just recently.

viewtopic.php?f=30&t=114604

...looks like it was a case of the Stock winding being too loose.

Anyway I would suggest that bigger wires are more difficult to wind with when the corners are very sharp.

If you have very gradual bends and plenty of clearances then it's okay, but if you are looking to make your life easier go with 26 AWG and then just decide how many Strands you need relative to the Winds.

Total Fill = Turns * Strands

For mine the Stock configuration is 11 Turns and 11 Strands making 121 Total Fill.

I'm going the opposite direction and REDUCING the kv to 14 Turns and 9 Strands making 126 Total Fill.

Obviously the kv is scaled up with fewer Turns and scaled down with more.

You need to build a spreadsheet table with your situation and scout around for optimum fill situations.

One Strand can translate to either being 5% too low or 5% too high sometimes.

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Re: Rewinding a 15470 outrunner

Post by trialspower2 » Jan 07 2022 11:41am

Thankyou for the information. So basically I could use the same thickness wire, but I need to double the number of strands and half the number of turns?

The other consideration I was looking at, was whether its best to use star or delta. I presume the motor is currently in delta as I don't think there is a start point connection.

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Re: Rewinding a 15470 outrunner

Post by SafeDiscDancing » Jan 07 2022 3:08pm

trialspower2 wrote:
Jan 07 2022 11:41am
Thankyou for the information. So basically I could use the same thickness wire, but I need to double the number of strands and half the number of turns?

The other consideration I was looking at, was whether its best to use star or delta. I presume the motor is currently in delta as I don't think there is a start point connection.
All of the above.

Basically your parameters are:

Delta or Wye (with a square root of 3 difference)

Thick or Thin Wire... or Keep the Wire constant and vary the number of Strands.

Number of Turns.

-----------------

I think there are "Copper Fill Winding Calculators" around somewhere on the internet but you can do simple math on your own.

What I find is certain combinations get better fill than others without going too far. Don't forget you actually need to achieve the wind itself which with little motors is tricky.

The RC forums have lot's of talk about it because it's central to the hobby.

You should attempt to simulate what is going on now with the GRIN Simulator which is the ebikes.ca website and with that you can see what will happen when you change a parameter. That could save a lot of effort.

Generally any change more than 10% is probably an error... in your case a huge jump in kV and you will not be able to spin the motor without hitting the ERPM limits which is my problem. At 4000 motor rpm my ERPM is maxed out, but the motor screams past it anyway and wants to detonate so I'm backing down the peak.

Number of Turns is directly connected to kV for a given choice of the Delta or Wye connection.

Your "fill factor" acts as an independent thing that will decide how efficiently the motor runs.

So first be certain of the desired kV then work backwards to consider what achieves it.

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Re: Rewinding a 15470 outrunner

Post by SafeDiscDancing » Jan 07 2022 5:31pm

trialspower2 wrote:
Jan 07 2022 9:43am
I have a couple of bikes, one with a 120100 50KV outrunner and the other with a 15470 27KV outrunner. After taking the gearing into account, both bikes have a top speed of around 40mph.
I jumped to answer the rewinding questions but didn't really think of this.

What you appear to be comparing is one motor designed for low rpm (27kV) with another for higher (50kV) but you have different gearing so the top speed is the same.

Remember that Power = Torque * RPM so if you already geared down the faster motor it does not take as much Torque to achieve what you want.

Most motors seem to be able to produce maximum power at 4000 to 6000 rpm.

So yeah your core assumption is probably correct... the more you can gear it down "assuming" a fixed motor size physically the more top end power.

My guess is your idea to test at 50 kV looks like a reasonable idea and then duplicate the same gearing and assuming the same controller then you will know which motor is at root the "better".

Another thing "could" trace back to the controller as defining the top because the Battery Current limit defines maximum power and wind resistance the load.

Again.... there are so many variables you should try to simulate it.

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Re: Rewinding a 15470 outrunner

Post by trialspower2 » Jan 08 2022 10:30am

Ultimately what I am interested in is initial torque from zero speed. But I also want to keep a decent top end speed.

I am using a speed controller which I designed and built myself and I am not limited on segment change speed, well within reason anyway, few micro seconds per segment minimum maybe.

When looking at the difference between star and delta, when considering star, in my mind one winding is always fully switched off at any one time. Would the motor cool better?

In delta, one winding sees full voltage, the other two windings are sharing the full voltage. What benefit do these two winding being energised at the same time bring?

In star, two windings see half the battery voltage, so are effectively fully energised. Does this mean more bottom end torque?

I can of course wind the motor for 50KV in start or delta, but which will be best in this application?

If I made a speed controller with totem pole 6 outputs, I could have full control over all windings at all times, could there be a benefit for this? has it been done before? could more zero speed torque be seen by energising them all in a certain sequence? or will 1 phase line up and make zero torque?

I am still trying to get my head around the 154mm outrunner, I think it has 40 magnets and 36 slots. I presume its wound AabBCcaABbcC or something similar. What I have noticed is every 10th magnet aligns with the stator.

As you can see, quite alot of questions at the moment, but I will keep researching! Might also draw the motor and colour code it so its more visual to see what aligns with what!

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Re: Rewinding a 15470 outrunner

Post by SafeDiscDancing » Jan 08 2022 10:43am

You are stepping into a world of immense beauty but also complexity.

These motors have fractional relationships between stator and magnet so that alone is something you can spend hours reading about. Three German guys doing RC airplanes realized that with fractional (mismatched) stator and magnet motors you could amplify the switching speed by several times.

14 to 12 is something like 7 to 6 so about 6/1 (but actually some smaller fraction like about 5) faster.

So your motor "Electrical Revolution Per Minute" (ERPM) goes bonkers and "spins" really fast while your motor is going slow.

The controller needs to be able to keep up and most cheap Chinese controllers cannot go that fast.

As for Delta vs Wye...

I have read people speculate that Wye will always be better because it cleans up the signal.

However, pretty much all the RC people use Delta and it is the most common winding because you can terminate everything with three simple wires.

This site is very good:

http://www.bavaria-direct.co.za/

Check out their winding calculator.

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Re: Rewinding a 15470 outrunner

Post by amberwolf » Jan 08 2022 3:34pm

trialspower2 wrote:
Jan 08 2022 10:30am

When looking at the difference between star and delta, when considering star, in my mind one winding is always fully switched off at any one time. Would the motor cool better?

In delta, one winding sees full voltage, the other two windings are sharing the full voltage. What benefit do these two winding being energised at the same time bring?

In star, two windings see half the battery voltage, so are effectively fully energised. Does this mean more bottom end torque?
Some thoughts:

Delta means less inductance; the controller has to be designed to deal with that, if it's really low. In high-current applications, there can be problems at the controller (FETs, gate drive, etc) if it's not able to handle this.

Delta means higher current (less winding resistance per phase), but lower torque constant. (Effectively Delta is something like winding a motor with less turns, since there is less winding in use at any one time.)

I'm not a motor expert by any means, but if I were going to rewind a motor anyway, I'd probably use Wye, and then just wind it for the specific torque and speed I was after. If I did not need to rewind it, but wanted to change it's speed or torque, I would change what the controller sends it (possibly by using a higher voltage battery to induce higher speed and a controller that can deliver more current, so the higher voltage at startup also induces higher currents).


Since you're after higher startup torque, there is a fair bit of info out there on Wye vs Delta regarding torque:
https://www.google.com/search?q=delta+vs+wye+torque
If you replace Wye with Star, there are also other pages.
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Re: Rewinding a 15470 outrunner

Post by trialspower2 » Jan 11 2022 5:22am

So after several hours of research I have come to the following conclusion regarding making a maximum torque motor. This is speaking generally and probably ignoring some of the finer details. We are talking about the torque the motor can make basically with a locked rotor.

The amount of torque a motor can make is limited because the stator becomes saturated.

Regardless of the motors KV, the saturation point of the stator is always the same. If the motor is low KV, and has for example 10 turns, and it becomes saturated at 10 amps, if you had a high KV motor with 1 turn, it would require 100amps to saturate. So ultimately both motors will make the same torque, but it will require a lot more current for the high KV motor to do it.

My guess is that the trade off is between loads of rear wheel torque from a large gear reduction and high motor losses at high speed due to high motor RPM. Heat caused by all the segment changes.

When you put a motor into star from delta it turns 1.73 times slower, but has 1.73 times more torque. Cant really get to the bottom of why, but my guess is with star, you effectively have two windings energized, which are both generating torque. With delta, 1 winding sees twice the current, so this is doing all the work and will become saturated when the second best aligned winding could still generate more torque.

Considering that in star you have two windings in series and you still get more torque, in my mind this must be the right way to go. So to get the same KV in star, you have half the turns, we have already established that the same torque can be generated regardless of the number of turns given enough current, surely the star will give 1.73 times the locked rotor torque of delta if enough current is supplied....

I realize this then comes down to the speed controller, but the one I have built should be able to stand over 200A with a locked rotor at say 30% duty cycle. So thats like 600A during the on time.

I am by no means saying the above is correct, but based of my research this is what I have come up with.

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Re: Rewinding a 15470 outrunner

Post by SafeDiscDancing » Jan 11 2022 9:55am

Best to just think:

"kV is just kV"

...really there are no significant differences between Delta vs Wye other than some potential resonances when the motor is at higher rpm.

Torque really comes down to either Current (which is where you get the heat with Amps^2 * Resistance) OR actual Gear reduction.

So for example one way some people achieved "instant Torque increase" was to switch to a smaller rear wheel... Presto !!! ...out of nowhere you have more Torque but a lower top speed.

Now assuming you gear it way down or switch to a microscopic rear wheel now you are faced with the "why can't I go fast" problem.

This is where the last bit of complete "hackery" enters where people apply "Field Weakening" which basically adjusts the Controller so that it's phase is out of whack and that gets the Motor to spin faster while dumping massive losses out as heat.

All the craziest stuff has been tried.

People have even tried Delta to Wye and back "two speeds" which don't achieve anything worthwhile.

Anyway... the only OTHER thing is motor cooling which can increase your Current carrying capacity and allow you to sustain higher Current loads longer.

Saturation is usually not the long term problem... heat is the problem... because with heat the resistance in the Copper increases and you see a sort of downward spiral of heating.

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Re: Rewinding a 15470 outrunner

Post by calab » Jan 11 2022 2:25pm

The delta wye angle is very interesting viewtopic.php?f=2&t=9215&hilit=delta&start=50#p147923 I know another that posted did it on his sailboat only to achieve 20rpm/v I dont have it handy but its recent on his solar ebike hub motor powered sailboat. I was thinking about doing it with the 3pdt switch but really have no need. However thinking of all the projects I have on the go right now which is only the razor stand up scooter build it might do me very well to do a delta/wye switch on the hub motor for the razor e200 built with ezee 500w hub motor.

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Re: Rewinding a 15470 outrunner

Post by trialspower2 » Jan 11 2022 3:10pm

by SafeDiscDancing » Jan 11 2022 9:55am

Best to just think:

"kV is just kV"
If you look at my original post, I have two bikes both geared for 40mph, one is a 120100 at 50KV and the other a 15470 at 27KV. The 120100 is massively out performing the 15470.

KV is not just KV.

If you have a 50KV 15470 outrunner and a 27KV 15470 outrunner, they both have the same magnets, both stators have the same limit for magnetism, at locked rotor the 50KV through an additional gear reduction will make more torque than the 27KV. As I explained above, it might need more current, but it will make the same torque as the 27KV, only the 2:1 gear reduction will double it!


Does anyone know anything about winding the motor with the coils in parallel rather than series and like have a ring main connecting them all together? Considering my 15470 outrunner, basically each phase winds round 3 groups of teeth, at 4 locations around the stator. If I split it into 4 parallel windings of 3 teeth. I presume each tooth would need 4 times as many turns, but I would have only 1 wire strand rather than 4? if you consider a series wind with the same wire thickness? Just thinking it will cut down on the resistance on the tails and a single wire if it would bend tight enough would pack well.

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Re: Rewinding a 15470 outrunner

Post by SafeDiscDancing » Jan 11 2022 3:36pm

trialspower2 wrote:
Jan 11 2022 3:10pm
KV is not just KV.
Actually in the CONTEXT of what I was saying... "it is".

The Delta vs Wye thing is the classic "rookie mistake" in that at the end of the day what matters is "Copper Fill".

Increase your "Copper Fill" and identify the correct number of Turns to achieve the desired kV and that's pretty much all you can do. And there are many combinations of Delta and Wye and Turns and Strands so I suggest to be systematic and create a spreadsheet with the necessary combinations. There might be about fifteen that would make sense.

Also....

You are somehow saying you think a 27kV that is "geared up" to match a 50kV are equal but that is not true at all.

Gearing is a factor.

All I'm saying is to "pause" and think this out more. Don't chase the Delta vs Wye nonsense.

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Re: Rewinding a 15470 outrunner

Post by mxlemming » Jan 11 2022 3:59pm

Max torque a motor can generate is given by the magnetic flux in the air gap.

The 120100 motor has a 105x60mm air gap. The 15470 has (i think) 137x40mm air gap.

Assuming they are similar magnetic fields, and normally they're designed to be a bit below 2 Tesla, the max torque is proportional to diameter square x length

120mm
105²*60=661500

154mm
137²*40=750760

The motors can deliver similar ultimate torque.

So with a 2x gear ratio difference, of course the 120mm one will out perform.

KV just changes the current to voltage ratio.
Hold my beer while I divide by zero :flame:

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Re: Rewinding a 15470 outrunner

Post by SafeDiscDancing » Jan 11 2022 4:06pm

mxlemming wrote:
Jan 11 2022 3:59pm
Another rather bizarre but very profound truth is that the stronger the magnet the SMALLER the field.

So the physical design should optimize the magnets in use.

Everything about the reality we THINK we know is inverted.

Matter is just Light that was "Shrunk".

And as Tesla once said... "Light is just a Sound wave in the Aether."

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Re: Rewinding a 15470 outrunner

Post by trialspower2 » Jan 11 2022 4:31pm

Max torque a motor can generate is given by the magnetic flux in the air gap.

The 120100 motor has a 105x60mm air gap. The 15470 has (i think) 137x40mm air gap.

Assuming they are similar magnetic fields, and normally they're designed to be a bit below 2 Tesla, the max torque is proportional to diameter square x length

120mm
105²*60=661500

154mm
137²*40=750760

The motors can deliver similar ultimate torque.
Thanks mxlemming, this is helpful. The width of the stator on the 15470 is 35mm, so I guess the air gap should be 137 x 35mm?

Do we not need to take into account that the 15470 has 32 slots, compared with the 120100 having 24? Not sure how many to consider active, say one winding, we have 12 on the 154mm and 8 on the 120mm?

so maybe
120mm
105 * 105 * 60 = 661500 * 8 = 5292000 (units?)

154mm
137 * 137 * 35 = 656916 * 12 = 7882992

So on a 2 x gear ratio difference we are 33% worse off. However have my doubts about the efficiency of the 15470 with such a low KV so could be worse than this.

It only has 23 x 0.3mm strands in each winding, which seems to me like nothing for the currents we are talking about.

When talking about star against delta, dont we have more pulling air gaps with fully excited windings?

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Re: Rewinding a 15470 outrunner

Post by mxlemming » Jan 11 2022 4:47pm

trialspower2 wrote:
Jan 11 2022 4:31pm
Max torque a motor can generate is given by the magnetic flux in the air gap.

The 120100 motor has a 105x60mm air gap. The 15470 has (i think) 137x40mm air gap.

Assuming they are similar magnetic fields, and normally they're designed to be a bit below 2 Tesla, the max torque is proportional to diameter square x length

120mm
105²*60=661500

154mm
137²*40=750760

The motors can deliver similar ultimate torque.
Thanks mxlemming, this is helpful. The width of the stator on the 15470 is 35mm, so I guess the air gap should be 137 x 35mm?

Do we not need to take into account that the 15470 has 32 slots, compared with the 120100 having 24? Not sure how many to consider active, say one winding, we have 12 on the 154mm and 8 on the 120mm?

so maybe
120mm
105 * 105 * 60 = 661500 * 8 = 5292000 (units?)

154mm
137 * 137 * 35 = 656916 * 12 = 7882992

So on a 2 x gear ratio difference we are 33% worse off. However have my doubts about the efficiency of the 15470 with such a low KV so could be worse than this.

It only has 23 x 0.3mm strands in each winding, which seems to me like nothing for the currents we are talking about.

When talking about star against delta, dont we have more pulling air gaps with fully excited windings?
The number of slots doesn't make a difference to the maximum torque produced, it's used to adjust the kV and to make the stator inner radius thinner thus lighter.



At the expense of higher erpm, which limits the max speed due to iron losses.

But repeat... Number of slots doesn't change the maximum torque. :wink:

Your ratio of ultimate motor torque is 661500 to 656916. The 120100 motor would produce more torque even at the same gear ratio if you just fed it 50/27x as much current.

Star vs Delta is slightly different for bldc and sinusoïdal but the difference won't be huge. Star is less affected by recirculating currents and harmonics (the recirculating currents theoretically don't exist but that's in a perfect motor).
Hold my beer while I divide by zero :flame:

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Re: Rewinding a 15470 outrunner

Post by trialspower2 » Jan 11 2022 5:43pm

But repeat... Number of slots doesn't change the maximum torque. :wink:
I wouldnt have believe you, but considering riding both bikes it does kind of make sense with the performance difference. New bike hardly has enough torque to lift front wheel, old bike you couldnt keep front wheel down!

Are the number of slots not considered because the motor diameter is already included in the calculation? I am struggling to get my head around this.

In your opinion, which motor would offer the best all round performance? 120100 or the 15470? We could also consider the 154100?

At the end of the day, this is a trials bike so locked rotor torque is everything, however will the large diameter of the 15470 cause more iron losses at higher RPM compared to the 120100?

I seem to think the 50KV 120100 was around 7.5A no load at 80V, the 27KV 15470 is 2.3A at 100V. What could we expect the 15470 to be at 50KV?

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Re: Rewinding a 15470 outrunner

Post by SafeDiscDancing » Jan 11 2022 6:39pm

So I did some research and looked up and compared your two motors based on what can be found online.

Obviously the shapes are VERY different. One has a large radius and is thin and the other is a smaller radius and is wide.

You are comparing very different motors despite the fact they are both rated about the same.

Also... I noticed the 15470 you have is at the lower 27kV and yet they do sell that at the 50kV level.

Here is a thought... is your voltage the problem?

What if you tried the 15470 at a voltage roughly 50/27 or about DOUBLE what you have now?

Then run at the same gear ratio.

------------------

You might find out what a 15470 is wound like in the 50kV and just copy that. My guess is the company will have already found the best copper scenario.

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Re: Rewinding a 15470 outrunner

Post by mxlemming » Jan 11 2022 6:42pm

trialspower2 wrote:
Jan 11 2022 5:43pm
But repeat... Number of slots doesn't change the maximum torque. :wink:
I wouldnt have believe you, but considering riding both bikes it does kind of make sense with the performance difference. New bike hardly has enough torque to lift front wheel, old bike you couldnt keep front wheel down!

Are the number of slots not considered because the motor diameter is already included in the calculation? I am struggling to get my head around this.

In your opinion, which motor would offer the best all round performance? 120100 or the 15470? We could also consider the 154100?

At the end of the day, this is a trials bike so locked rotor torque is everything, however will the large diameter of the 15470 cause more iron losses at higher RPM compared to the 120100?

I seem to think the 50KV 120100 was around 7.5A no load at 80V, the 27KV 15470 is 2.3A at 100V. What could we expect the 15470 to be at 50KV?
The iron loss scales roughly with rpm squared I recall so 2700rpm 2.3A 100V... 230W on the 154 vs
4krpm 7.5A 80V... 600W on the 120

They're not hugely different efficiency wise. They're the same max torque. You'll have to gear them the same.

Bigger motor is bigger. The two you've tried so far are the same size but different shape.

The 154100 might be substantially better, you know the stator dimensions? Could be nearly double the 15470
Hold my beer while I divide by zero :flame:

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Re: Rewinding a 15470 outrunner

Post by mxlemming » Jan 11 2022 6:45pm

Post some pics of this stuff. I read your building an ESC thread, sounds like you had one of the earlier endless sphere super high power controllers. Kudos.

Unfortunately a lot of the pics are no longer there
Hold my beer while I divide by zero :flame:

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Re: Rewinding a 15470 outrunner

Post by mxlemming » Jan 11 2022 7:28pm

SafeDiscDancing wrote:
Jan 11 2022 6:39pm



What if you tried the 15470 at a voltage roughly 50/27 or about DOUBLE what you have now?

Then run at the same gear ratio.

------------------
.
This.
Or rewind to 50kV and run the same gear ratio, it amounts to the same thing.
Hold my beer while I divide by zero :flame:

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Re: Rewinding a 15470 outrunner

Post by trialspower2 » Jan 12 2022 6:18am

by mxlemming » Jan 11 2022 6:45pm

Post some pics of this stuff. I read your building an ESC thread, sounds like you had one of the earlier endless sphere super high power controllers. Kudos.

Unfortunately a lot of the pics are no longer there
I made about 7 different speed controller designs over a few year period before I got to where I am now with it. I designed them myself, and wrote the code. They all used a dspic30f microcontroller. The design I ended up with is all surface mount. I will try and post some pics this evening.

I think the 154100 motor would have a 60mm wide stator, so we would be looking at 137x137 x 60 = 1126140. No doubt we would have bigger losses at high RPM.

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Re: Rewinding a 15470 outrunner

Post by SafeDiscDancing » Jan 12 2022 10:31am

mxlemming wrote:
Jan 11 2022 7:28pm
This.
Or rewind to 50kV and run the same gear ratio, it amounts to the same thing.
I see the problem. The guy is asking questions about basic kV issues while at the same time very deeply into software coding.

As we know software is all about abstractions... the virtual realities.

So to anyone looking it's very obvious to see "oh, he simply needs the voltage increased" but his mind is focused on where he wants it to go even if simple honest sincere advice is dismissed.

This happens a lot.

In fact sometimes the deeper someone goes into the software side the more you start to ignore the beauty that is the real reality that is this dielectric / magnetic world we live in. (as in the Tesla wisdom)

As I see it this is a simple problem of needing to drive his 27kV motor at a voltage to equalize it with one at 50kV and at that point you finally are making really clear headed comparisons of motor performance.

Motors do have differences and often they can have odd unexpected behaviors due to their design but you always need that open mind to look at what you have.

Grammar, Logic, Rhetoric... the Grammar is the Evidence, the input, the "listening" part.

We all need more of it... my self included because I can fail to listen just as often.

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Re: Rewinding a 15470 outrunner

Post by trialspower2 » Jan 12 2022 11:46am

by SafeDiscDancing » Jan 12 2022 10:31am

mxlemming wrote: ↑Jan 11 2022 7:28pm
This.
Or rewind to 50kV and run the same gear ratio, it amounts to the same thing.
I see the problem. The guy is asking questions about basic kV issues while at the same time very deeply into software coding.

As we know software is all about abstractions... the virtual realities.

So to anyone looking it's very obvious to see "oh, he simply needs the voltage increased" but his mind is focused on where he wants it to go even if simple honest sincere advice is dismissed.

This happens a lot.

In fact sometimes the deeper someone goes into the software side the more you start to ignore the beauty that is the real reality that is this dielectric / magnetic world we live in. (as in the Tesla wisdom)

As I see it this is a simple problem of needing to drive his 27kV motor at a voltage to equalize it with one at 50kV and at that point you finally are making really clear headed comparisons of motor performance.

Motors do have differences and often they can have odd unexpected behaviors due to their design but you always need that open mind to look at what you have.

Grammar, Logic, Rhetoric... the Grammar is the Evidence, the input, the "listening" part.

We all need more of it... my self included because I can fail to listen just as often.
I am not really sure what you are getting at here, or what exactly you are trying to say. But I have built a complete trials bike with the help from my brother, using motorbike rims and tyres, a 120100 outrunner, 1300W battery pack and the complete bike weighs under 48kg. This includes my own speed controller and BMS. The bike performs so well that it can hold its own against petrol machines. We have now gone on, with the investment from a UK company to build a second model with a 15470 outrunner and 1900W battery pack which is fully waterproof and weighs in at 51kg. It has just been a big set back having the torque issue, which with help from the community on here we can now address. Other than this, the bike is 99% complete. I will post pictures of the bikes in the coming months, however currently they have not been out in the public eye. To maximize the performance of the bike, I have to understand how every part of it works, the information I needed was that regardless of KV rating the maximum torque for a motor is the same.

Cheers
Danny

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