How to get the most power out of a QS205 50H?

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Darren2018   100 W

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How to get the most power out of a QS205 50H?

Post by Darren2018 » Nov 15 2020 9:45am

I am wondering how to get the most power out of this setup:

QS205 50H (kV not decided)
Nucular 24F at 300bA/500pA
25" total wheel size
10-50mph


I know the basic theory is to condense the motors available power into a useful rpm range but as we all know this is not as easy as it sounds when the motor is mounted within the wheel itself as the most significant tuning variables are now void. To pick the motor that maximises the bA and pA limits is not too difficult but I would like to choose a motor that has a wide and useful power band. Would a 3.5T plus field weakening be best? Spinningmagents mentioned this combination and it makes sense. Is anyone running 500pA on a QS205 3.5T with field weakening?

5T vs 3.5T. Notice how much extra power is available from 15mph onwards
Screen Shot 2020-11-15 at 12.58.45 pm.png
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Even when the battery is at 50% the 3.5T still has loads more useful power
Screen Shot 2020-11-15 at 13.02.26 pm.png
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I think the 4T with field weakening might be the best option if the Nucular controller is ever able to be run on 24S as you will not be capped on pA like you are on the 3.5T and the extra speed that the 3.5T is capable of requires a lot of power to sustain it anyway. I don't think the top speed is an issue for either motor especially once field weakening is applied so at this point getting more lower end torque would probably be better. I am aware that heat will become a problem but primarily my bike will be used like a regular 350W ebike so I am not too worried plus Hubsinks and Statoraid will enable the motor to cool much faster.

4T 24S vs 3.5T 22S
Screen Shot 2020-11-15 at 13.42.20 pm.png
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Who else is running any of these combinations? Anyone know of any high powered mid drive frames that keep the pedals and regular bike seat?

j bjork   100 kW

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Re: How to get the most power out of a QS205 50H?

Post by j bjork » Nov 15 2020 2:02pm

I think a 4T would be a good choice, but I havent tried any other winds.
I think you are really pushing the limits with 95V, but it might work..

I have this combination on the "stealth bomber"
It starts loosing power at higher speeds, but I dont think it is a problem.
Not on the kind of riding I have done anyway. I think it does about 80kph without fw and 100 with, but I am not sure if I remember right. That is with a 16" rim. There are probably more info in the build thread.

john61ct   100 GW

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Re: How to get the most power out of a QS205 50H?

Post by john61ct » Nov 15 2020 2:24pm

Your premise already locks in all the variables that determine overall POWER.

If you are also locking in voltage at the high end then your Kv choice will not change anything except the V vs A curve as rpm climb

and a tiny bit of shifting what speed range gives the best Wh per mile efficiency.

Assuming the same copper mass between the different windings.

I hope @Balmorhea and @John in CR will be along to clarify / correct the above

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Re: How to get the most power out of a QS205 50H?

Post by j bjork » Nov 15 2020 2:31pm

As you can see in this case 500pA is max, and possibly 95V. So now it is a matter of choosing the most suitable wind. If there was no pA limit a 3T would be a better choice to get max power.

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Re: How to get the most power out of a QS205 50H?

Post by john61ct » Nov 15 2020 2:47pm


john61ct   100 GW

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Re: How to get the most power out of a QS205 50H?

Post by john61ct » Nov 15 2020 2:48pm

j bjork wrote:As you can see in this case 500pA is max, and possibly 95V. So now it is a matter of choosing the most suitable wind. If there was no pA limit a 3T would be a better choice to get max power.
Could you please explain this in more detail?

Starting with, what is this "pA" unit?

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Re: How to get the most power out of a QS205 50H?

Post by j bjork » Nov 16 2020 1:22am

pA= phase amp
bA= battery amp

There is not much use for the discussion about all windings are capable of the same output, it is just a matter of changing the amp and volt relationship. As the max amp and volt is already set in this case.

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Re: How to get the most power out of a QS205 50H?

Post by john61ct » Nov 16 2020 1:58am


j bjork wrote:pA= phase amp
bA= battery amp
Ah of course, thanks
j bjork wrote:As you can see in this case 500pA is max, and possibly 95V. So now it is a matter of choosing the most suitable wind. If there was no pA limit a 3T would be a better choice to get max power.
Could you show the math?

How does the 500pA max eliminate a 3T wind for this motor?

So I assume there must be more turns (lower Kv, more torque output per current amp)

As I understand, the idea is to match that available power to the desired top speed.

So let's say everything else is the same as OP stated, but Case A wants 40mph, while Case B wants 60mph. For simplicity, let's take FW out of the picture.

Of course, anyone can answer, but please show the math!

TIA


Darren2018   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Darren2018 » Nov 16 2020 2:52am

j bjork wrote:
Nov 15 2020 2:02pm
I think a 4T would be a good choice, but I havent tried any other winds.
I think you are really pushing the limits with 95V, but it might work..

I have this combination on the "stealth bomber"
It starts loosing power at higher speeds, but I dont think it is a problem.
Not on the kind of riding I have done anyway. I think it does about 80kph without fw and 100 with, but I am not sure if I remember right. That is with a 16" rim. There are probably more info in the build thread.
j Bjork what settings are you running on your 24F? What has been your experience with different settings? Does the 4T do 500pA without any problems? How many 0-100 pulls would you say is possible before needing to let the motor cool?

Darren2018   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Darren2018 » Nov 16 2020 3:11am

john61ct wrote:
Nov 16 2020 1:58am
j bjork wrote:pA= phase amp
bA= battery amp
Ah of course, thanks
j bjork wrote:As you can see in this case 500pA is max, and possibly 95V. So now it is a matter of choosing the most suitable wind. If there was no pA limit a 3T would be a better choice to get max power.
Could you show the math?

How does the 500pA max eliminate a 3T wind for this motor?

So I assume there must be more turns (lower Kv, more torque output per current amp)

As I understand, the idea is to match that available power to the desired top speed.

So let's say everything else is the same as OP stated, but Case A wants 40mph, while Case B wants 60mph. For simplicity, let's take FW out of the picture.

Of course, anyone can answer, but please show the math!

TIA
Yes you are right. The people running the mid drive setups are able to focus all of the motors potential into the wheel rpm range that they choose via sprockets which means not much thought is required when choosing a motor. I am trying to make the best out of a traditional hub by careful selecting the motor winding based on the controller specifications, wheel size, battery voltage, riding conditions and speed. As far as I am aware most people do not do this and simply just buy a 5T as torque or 3T as speed without understanding how much potential power they may be missing out on. It has been discussed on here before but I still think that people may not quite understand and being new to this myself I thought I would highlight these advantages and disadvantages so I can understand it better and learn from anyone else who has experience with this setup or knows the best way to focus the motors power.

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Re: How to get the most power out of a QS205 50H?

Post by j bjork » Nov 16 2020 3:16am

I run 500pA and maybe 400? bA (max)
A bit voltage limited, I run 20s often at 82V.
I think it is over 400pA that it gets interesting, wheelies on a throttle tap.
Even though qs clames about 300pA max it still makes a difference to go a lot higher.

I dont know how many 0-100 pulls it can take, but it dosent take long. So I guess a few..

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Re: How to get the most power out of a QS205 50H?

Post by j bjork » Nov 16 2020 6:18am

john61ct wrote:
Nov 16 2020 1:58am

How does the 500pA max eliminate a 3T wind for this motor?
You are right, it dosent. The 3T would probably have higher peak power than any of the ones in the examples. But at the cost of torque when we are limited to 500pA.
I dont know the math, but I think 3/4=0,75. That would mean the 3T would have 75% of the torque of the 4T at the same phase amps. In reality the difference would be smaller because of saturation and other losses.

The 3,5T might look interesting, but I think I have read about uneven heating in the half turn motors. And how is the copper fill?

Darren2018   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Darren2018 » Nov 16 2020 7:18am

j bjork wrote:
Nov 16 2020 6:18am
john61ct wrote:
Nov 16 2020 1:58am

How does the 500pA max eliminate a 3T wind for this motor?
You are right, it dosent. The 3T would probably have higher peak power than any of the ones in the examples. But at the cost of torque when we are limited to 500pA.
I dont know the math, but I think 3/4=0,75. That would mean the 3T would have 75% of the torque of the 4T at the same phase amps. In reality the difference would be smaller because of saturation and other losses.

The 3,5T might look interesting, but I think I have read about uneven heating in the half turn motors. And how is the copper fill?
I highlighted this in the graphs but remember that it is only at full 22s battery voltage. I don't think that it would be a reason not to choose the faster winding but if you were able to run 100V via the Nucular then imo the 4T is the best option.

I have read about the uneven heating of half turn motors but I wondered exactly how much difference it actually makes. I have the sales/data sheet for the 205 and from the data that is included it looks like the 4.5T has the highest copper fill assuming that the strands are the same diameter although I may be completely wrong.
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Jonno   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Jonno » Nov 16 2020 1:03pm

Hi Guys,
I'm running a QS273 V3 3.5t with a 24F @ 22s 92.4v at the moment.
100% reliable for the past 2000+ miles
I've not measured acceleration times but it's brisk.

I've also got a QS205 3.5t on a EM150 @ 20s 84v
....... slower than the above but still quick.
Modified EEB frame, 888 forks, 280mm DNM pit bike shock, QS273 40h V3 3.5t, Nucular Electronics 24F controller 350a, 92V @ 36ah 26650 cells, 300a BMS with bypass,
Hope V4 + Galfer 223mm discs + Variable regen braking. PWM fan cooling.
.......and some other QS205 & QS273 bikes :confused:

Darren2018   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Darren2018 » Nov 16 2020 2:06pm

Jonno wrote:
Nov 16 2020 1:03pm
Hi Guys,
I'm running a QS273 V3 3.5t with a 24F @ 22s 92.4v at the moment.
100% reliable for the past 2000+ miles
I've not measured acceleration times but it's brisk.

I've also got a QS205 3.5t on a EM150 @ 20s 84v
....... slower than the above but still quick.
Thanks Jonno. Have you tried any other windings on your setup? I am guessing that you are running the full 500 pA, do you run field weakening as well? How does the motor cope with back to back runs? I am wondering if it is worth saving the extra 3kg and going for a MXUS 3K 3T as ferrofluid is lighter and less expensive than the extra copper. What do you think?

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Re: How to get the most power out of a QS205 50H?

Post by Jonno » Nov 16 2020 2:31pm

MXUS - got a burnt out one somewhere - nuff said

I run the full 300ba and 500pha with a custom throttle curve and 123% flux

I've own another 24f on a mates Sur-ron 60v with bms bypass and I'm just Building a 20s sony vtc6 pack for it. When his 24f arrives I'll put it on the QS205.
Modified EEB frame, 888 forks, 280mm DNM pit bike shock, QS273 40h V3 3.5t, Nucular Electronics 24F controller 350a, 92V @ 36ah 26650 cells, 300a BMS with bypass,
Hope V4 + Galfer 223mm discs + Variable regen braking. PWM fan cooling.
.......and some other QS205 & QS273 bikes :confused:

Darren2018   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Darren2018 » Nov 17 2020 1:17am

I won't use the MXUS then. The custom throttle with field weakening sounds like it would be good. You obviously can't add more than the limits though right? Without customising the throttle would it be like this?
Screen Shot 2020-11-17 at 05.25.46 am.png
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So with the custom throttle curve you can essentially add the torque where needed rather than having it run all the way to the end where drag is much higher? How much can be added? Would it potentially look like this?
Screen Shot 2020-11-17 at 06.05.01 am.png
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Jonno   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Jonno » Nov 17 2020 2:05am

Basically you have 8 points on the throttle that you can give a % value to - the same goes for braking as well.
for instance:
Throttle start: 8%
1: 25%
2: 35%
3: 48%
4: 60%
5: 70%
6:88%
Throttle end: 100%
You also have a choice of torque mode, speed mode or a combination of both.
Have a read in documentation @ https://nucular.tech/
Last edited by Jonno on Nov 17 2020 3:23pm, edited 1 time in total.
Modified EEB frame, 888 forks, 280mm DNM pit bike shock, QS273 40h V3 3.5t, Nucular Electronics 24F controller 350a, 92V @ 36ah 26650 cells, 300a BMS with bypass,
Hope V4 + Galfer 223mm discs + Variable regen braking. PWM fan cooling.
.......and some other QS205 & QS273 bikes :confused:

Darren2018   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Darren2018 » Nov 17 2020 9:58am

So it is not possible to increase the torque right after the pA start to decrease? What is confusing me is how fast you can make a 5T 205 in comparison to a 3T 205 just by adding field weakening because if it did not start where the pA start to decrease then the performance increase would either not be smooth or there wouldn't be much performance increase at all. Nobody seems to know what the power increase looks like on a graph. :confused:

Jonno   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Jonno » Nov 17 2020 10:41am

Modified EEB frame, 888 forks, 280mm DNM pit bike shock, QS273 40h V3 3.5t, Nucular Electronics 24F controller 350a, 92V @ 36ah 26650 cells, 300a BMS with bypass,
Hope V4 + Galfer 223mm discs + Variable regen braking. PWM fan cooling.
.......and some other QS205 & QS273 bikes :confused:

Darren2018   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Darren2018 » Nov 17 2020 11:48am

This is a good test but there are so many unanswered questions like controller max current, voltage, field weakening or none etc etc. All of these variables will make a big difference. The only bit of information I need to make a decision on 5T vs 4T vs 3.5T is how field weakening effects the torque curve. The way it reads on the Nucular controller documentation is that it is added once the motor rpm is at its maximum but how that looks on a graph is beyond me. If extra torque wasn't created before the max rpm was reached it would look weird.

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Re: How to get the most power out of a QS205 50H?

Post by Jonno » Nov 17 2020 4:00pm

On the video it demonstrates the difference in acceleration between the windings of the QS205 they are the same settings apart from that.
As for power i presume you have test ridden a QS205 @ 300ba.
The last test pilot to ride my QS273 came back and said "It lifts the front @ 45mph :shock: "
so I don't think your 10 - 50mph from earlier should be a problem
As for acceleration and heat -battery cooling is more of a problem that motor heat


Jonno
Modified EEB frame, 888 forks, 280mm DNM pit bike shock, QS273 40h V3 3.5t, Nucular Electronics 24F controller 350a, 92V @ 36ah 26650 cells, 300a BMS with bypass,
Hope V4 + Galfer 223mm discs + Variable regen braking. PWM fan cooling.
.......and some other QS205 & QS273 bikes :confused:

Darren2018   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Darren2018 » Nov 18 2020 4:54am

Jonno wrote:
Nov 17 2020 4:00pm
On the video it demonstrates the difference in acceleration between the windings of the QS205 they are the same settings apart from that.
As for power i presume you have test ridden a QS205 @ 300ba.
The last test pilot to ride my QS273 came back and said "It lifts the front @ 45mph :shock: "
so I don't think your 10 - 50mph from earlier should be a problem
As for acceleration and heat -battery cooling is more of a problem that motor heat


Jonno
I totally get that both bikes were equal but that is exactly my point. The controllers shouldn't have been the same because the windings were different which made the 5T look like it has torque which the 4T doesn't. The resistance of the 4T is lower so to keep things fair it should have had more current and a lower voltage which would have taken away its top speed advantage and given it more torque. This is why I am interested to hear from people who have the same controller as it is quite unique in being able to do 90V 300A/500A, as far as I am aware for years the popular choice for these 205x50 and similar motors has been ~72V 150A/350A which now seems pathetic since a few grams of ferrofluid and hubsinks are able to extract the heat whilst making the power much more reliable. Without the extra voltage and current available from the controller along with the ferrofluid and hubsinks this new trend of 25kW+ QS205 would not be possible. 5T imo is no longer the favourable choice and I have a feeling that running high amounts of copper may also become less favourable as once you know how much you need you can just buy enough to get the job done rather than buying it to act as a rudimentary heatsink which is what once was done when ferrofluid didn't exist and water cooling or air holes were all that was available to use the rarer, more expensive and more powerful controllers. I am not sure if you have noticed but higher powered cells are also becoming more readily available which is allowing people to have more power density for less money which used to be only achievable with a low capacity, heavy and bulky lipo pack. Most 18650 high power cells are 25A+ capable and readily available and a consumer grade hobby king 6Ah lipo is able to supply over 1600A. Power is no longer difficult to achieve it just needs the right combination of parts with perhaps a little bit of custom engineering to tie it all together.
Last edited by Darren2018 on Nov 18 2020 12:28pm, edited 1 time in total.

Jonno   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Jonno » Nov 18 2020 10:02am

Having built 8 of these bikes in various forms and modified a couple of Sur-Rons for friends I am only offering my own experience.

The 1st one I built cost in excess of £7000+ due to being a development bike (including lipos @ 126V 35+kw)

I'm waiting for parts to make 3 more QS205 4t 84v @150ba -300ba - some with 18650 vtc6 cells some with 26650s

3.5t or 4T is a good choice if you want both torque and speed for both on and off road.
Modified EEB frame, 888 forks, 280mm DNM pit bike shock, QS273 40h V3 3.5t, Nucular Electronics 24F controller 350a, 92V @ 36ah 26650 cells, 300a BMS with bypass,
Hope V4 + Galfer 223mm discs + Variable regen braking. PWM fan cooling.
.......and some other QS205 & QS273 bikes :confused:

Darren2018   100 W

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Re: How to get the most power out of a QS205 50H?

Post by Darren2018 » Nov 18 2020 12:25pm

Jonno wrote:
Nov 18 2020 10:02am
Having built 8 of these bikes in various forms and modified a couple of Sur-Rons for friends I am only offering my own experience.

The 1st one I built cost in excess of £7000+ due to being a development bike (including lipos @ 126V 35+kw)

I'm waiting for parts to make 3 more QS205 4t 84v @150ba -300ba - some with 18650 vtc6 cells some with 26650s

3.5t or 4T is a good choice if you want both torque and speed for both on and off road.
I have exactly none, the only thing I have built is a BBSHD which I modded to 45A :lol: . This next QS205 with Nuc24 build will be my first proper build and I don't want to get it wrong which is part of the reason why it has taken over a year of planning. My views were very different a year ago. I wish I had the money to be able to actually try the various bits of new tech available but either way I am quite certain that this new bike will be good. Following your advise I will be sticking with the QS205 3.5T as although I think the MXUS 3K 3T could put out very similar power I am not certain and I know by choosing what others have already tried I can't go too far wrong.

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