speed difference between turn counts

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krombopulos_michael   1 mW

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speed difference between turn counts

Post by krombopulos_michael » Jul 17 2018 2:17pm

my ebike has a MXUS 3000W V2 4T motor laced in 19" motorcycle wheel which maxes out around 40mph on flat road with a fully charged 72V 50A continuous battery. I'm strongly considering getting the V2 3T option (if I can find one) for more speed so I can switch out the stators depending on where I'm riding. My question is, what is max speed of 3T motor when using a 72V battery? Already used the motor simulator on ebikes.ca to get a general estimate but was wondering if anybody here has some first-hand experience with using the MXUS V2 3T motor with 72V battery.

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Re: speed difference between turn counts

Post by nfmisso » Jul 17 2018 5:19pm

To make an estimate, some information is required.

At your current maximum speed:
  • how much current was the motor drawing.
  • what was the voltage at the output of the controller or input to the motor (RMS with respect to ground for each of the three terminals averaged over at least one second).
  • what is the terminal to terminal DC resistance of the motor. (motor not connected to the controller)


With the above, we can determine if you speed is BEMF limited or current limited.

If it is BEMF limited, the 3T will be faster (and using the above data, it is not difficult to calculate how much faster.

If is is current limited, the 3T will be slower.

krombopulos_michael   1 mW

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Re: speed difference between turn counts

Post by krombopulos_michael » Jul 17 2018 5:30pm

I do not have a cycleanalyst or any other type of gauge to monitor battery and motor info so I'm not sure how much current was being drawn. Also not sure about the output voltage but the battery was close to fully charged so I would say about 82V. I am not aware of what the terminal to terminal DC resistance is nor do I know how to find it so if you could enlighten me then that'd be great. Since my battery is 20s5p using panasonic GA cells with 50A continuous and 70A max BMS then I think it could possibly be current limited

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Re: speed difference between turn counts

Post by amberwolf » Jul 17 2018 11:13pm

Current limiting is done in the controller, so if it's a "30A" controller, then 30A is the approximate battery current drawn at max. (it could peak a bit higher). So whatever it's rating is.....


What speed does the driven wheel go if you put the driven wheel off the ground and run it at full throttle?

What speed does the same wheel go while riding at full throttle on level ground with no headwinds?

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Re: speed difference between turn counts

Post by krombopulos_michael » Jul 18 2018 1:45pm

I'm using a 18 MOSFET AOT290L sine wave controller with 80A peak current. Bike reaches 41mph on flat road with no wind. Not sure about the exact unloaded speed though. Just want to know if my battery pack and controller can provide enough power to the motor to get the bike above 50mph.

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MadRhino   100 GW

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Re: speed difference between turn counts

Post by MadRhino » Jul 18 2018 2:16pm

Post your controller settings, and battery details.

18 fet controllers can feed a lot of power when they are set to. Those with 4110 mosfets, can be mod to pull 150A battery current and feed avove 300A phase current. It doesn’t mean that your controller is actually set to feed enough current to beat 50 Mph on your bike. We don’t even know how much current your bike would need to do it. Many factors are to be taken into account: Wheel size and total riding weight first.

Then, your battery may not be able to feed enough. We know nothing about it.

The simple way to go faster is higher voltage. Even if your system would need more power to go faster, higher voltage does translate into more watts per Amp and it would make faster speed with your actual motor. A faster Motor Kv, would require even more current.
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krombopulos_michael   1 mW

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Re: speed difference between turn counts

Post by krombopulos_michael » Jul 18 2018 2:54pm

Controller Settings:
50A Battery Current
120A Phase Current

Battery Details:
72V 17.5ah (20s5p)
Panasonic/Sanyo GA cells
50A continuous 70A max BMS

Other Factors:
19" moto rim with 2.25" tire
200lbs total riding wight (me+bike)

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Re: speed difference between turn counts

Post by Tommm » Jul 18 2018 10:33pm

He is pushing 3.6kw, 40mph/60kph is nothing for that amount of power. The limit is the turn count and nothing else. It could be helped by a bigger wheel(wouldn't recommend it), using phase weakening if you only need more speed in bursts, or getting a higher voltage pack.

Since your battery is 50A, if you went for a lower turn count motor, the same gain that you get as a higher top speed you would lose on acceleration, and since you are battery limited for amps, there would be no way for you to get it back.

If your controller doesn't support it, and you don't have a huge investment in the controller, getting one that can do phase weakening would net you about a 20% higher top speed, this is probably the cheapest and simplest method.

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Re: speed difference between turn counts

Post by Dulel » Jul 19 2018 12:06am

You should be aware that battery is already at its limit. For that battery 25A continius is high load already and will shorten battery life. 50A you can take for only few seconds. My advice is don't push it over the limit, 40mph already takes 30A or more.
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Re: speed difference between turn counts

Post by markz » Jul 19 2018 1:51am


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Re: speed difference between turn counts

Post by icherouveim » Jul 19 2018 2:29am

krombopulos_michael wrote:
Jul 17 2018 2:17pm
my ebike has a MXUS 3000W V2 4T motor laced in 19" motorcycle wheel which maxes out around 40mph on flat road with a fully charged 72V 50A continuous battery. I'm strongly considering getting the V2 3T option (if I can find one) for more speed so I can switch out the stators depending on where I'm riding. My question is, what is max speed of 3T motor when using a 72V battery? Already used the motor simulator on ebikes.ca to get a general estimate but was wondering if anybody here has some first-hand experience with using the MXUS V2 3T motor with 72V battery.
I agree with the other guys. I have exactly the same motor laced in a 24" inch wheel (similar diameter with 19" moto rim). My top speed without Adaptto's field weakening is about 62-64 Km/h only.
So you cannot go any faster if your controller doesn't support over speed function.
I think I had to buy 3T motor because the torque 4T motor gives me after 40-50km is very week and only when I use OVS 6 setting I am satisfied on the other hand the efficiency goes down.
Also your battery is very weak and if you go for example 75km/h for some time it will overheat.

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Re: speed difference between turn counts

Post by krombopulos_michael » Jul 19 2018 10:49am

My controller has both a flux weakening and overspeed programable options. Right now the 3rd power toggle on my throttle is programmed for 110% speed and 100% current. I’ve never messed with the flux weaking parameter though because I’ve never been sure what it does. Could anyone describe what flux weakening actually does instead of saying that it increases top speed and decreases effeciency? By how much does flux weakening increase your top speed and how bad is it for the battery(how many more watt hours do you burn through)? Also what XPD program parameters should I be using to get the max speed out of my motor given that I only have max 84V to work with. If I can get my 4T motor near 48mph by reprograming the controller and adding ferrofluid to motor then I’ll be satisfied for now.

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Re: speed difference between turn counts

Post by Chalo » Jul 19 2018 11:37am

Tommm wrote:
Jul 18 2018 10:33pm
He is pushing 3.6kw, 40mph/60kph is nothing for that amount of power.
My quick check using the Kreuzotter speed calculator suggests that 3600W of mechanical power to the wheel would only result in 42mph on level ground. So the fact that he's getting 40mph means he's doing really well with what is optimistically about 3000W after efficiency losses.

In this case, a faster winding would result in lower top speed unless there were more current available to push it.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: speed difference between turn counts

Post by Chalo » Jul 19 2018 11:41am

krombopulos_michael wrote:
Jul 19 2018 10:49am
If I can get my 4T motor near 48mph by reprograming the controller and adding ferrofluid to motor then I’ll be satisfied for now.
According to my calculations, you're running close to the maximum speed you can expect from your available gross power. For higher speed, you'll need improved efficiency. Optimizing your aerodynamics will help most, followed by reducing rolling resistance.

What kind of bike is it?
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

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Re: speed difference between turn counts

Post by MadRhino » Jul 19 2018 12:10pm

krombopulos_michael wrote:
Jul 19 2018 10:49am
My controller has both a flux weakening and overspeed programable options. Right now the 3rd power toggle on my throttle is programmed for 110% speed and 100% current. I’ve never messed with the flux weaking parameter though because I’ve never been sure what it does. Could anyone describe what flux weakening actually does instead of saying that it increases top speed and decreases effeciency? By how much does flux weakening increase your top speed and how bad is it for the battery(how many more watt hours do you burn through)? Also what XPD program parameters should I be using to get the max speed out of my motor given that I only have max 84V to work with. If I can get my 4T motor near 48mph by reprograming the controller and adding ferrofluid to motor then I’ll be satisfied for now.
Magnetic flux weakening is achieved by frequency increase, when higher speed is desired that can be achieved with available voltage. Higher frequency, while weakening the magnetic flux ‘tricking’ the motor to higher Kv, does reduce torque thus taxing efficiency.

Actually, you are now pulling very close to the best performance that can be achieved with your combo motor/battery. The battery is your most important limiting factor. Addind some cells in the series would make you gain some speed, adding some series AND parallel cells would make you gain a lot of speed. A faster motor is not an option alone, adding some parallel cells would be required to feed it. So, a bigger battery is your first need, or higher C-rate cells.
Last edited by MadRhino on Jul 19 2018 12:24pm, edited 2 times in total.
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Re: speed difference between turn counts

Post by Tommm » Jul 19 2018 12:18pm

Chalo wrote:
Jul 19 2018 11:37am
Tommm wrote:
Jul 18 2018 10:33pm
He is pushing 3.6kw, 40mph/60kph is nothing for that amount of power.
My quick check using the Kreuzotter speed calculator suggests that 3600W of mechanical power to the wheel would only result in 42mph on level ground. So the fact that he's getting 40mph means he's doing really well with what is optimistically about 3000W after efficiency losses.

In this case, a faster winding would result in lower top speed unless there were more current available to push it.
For me on mountainbike setting at 3600w it says 48.6mph/78.3kmh.
40mph/60kph is what my legs can take me up to with a sprint with a bbs02 assisting me, and my toothpick legs certainly don't put out even 1kw.
krombopulos_michael wrote:
Jul 19 2018 10:49am
My controller has both a flux weakening and overspeed programable options. Right now the 3rd power toggle on my throttle is programmed for 110% speed and 100% current. I’ve never messed with the flux weaking parameter though because I’ve never been sure what it does. Could anyone describe what flux weakening actually does instead of saying that it increases top speed and decreases effeciency? By how much does flux weakening increase your top speed and how bad is it for the battery(how many more watt hours do you burn through)? Also what XPD program parameters should I be using to get the max speed out of my motor given that I only have max 84V to work with. If I can get my 4T motor near 48mph by reprograming the controller and adding ferrofluid to motor then I’ll be satisfied for now.
A lot of smarter people than me have wrote what it does on this forum, you can look it up, basically, if you are RPM and not power limited at the top speed (from my calculations for arguments sake let's assume it is the case(it is)) flux weakening will change the the signals sent to the motor along with dumping even more amps into it, it will help you reach the power limit instead of the RPM one.
For example, if you have a motor geared for 25mph top speed, you will be using just 5A at top speed even with a 8A controller and battery. With flux weakening if you gain 20% RPM, a usually attainable number, you will go 30mph and draw ~8A.

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Re: speed difference between turn counts

Post by markz » Jul 19 2018 12:55pm

I play around with the motor simulator a lot, just to see the characteristics of different settings.
You can post the graph with your selected settings and not the default.
Like this
http://www.ebikes.ca/tools/simulator.ht ... .03_V&hp=0
I am not sure what its called, but its a great feature as the settings are apart of the web url address.

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Re: speed difference between turn counts

Post by Chalo » Jul 19 2018 1:03pm

Tommm wrote:
Jul 19 2018 12:18pm
For me on mountainbike setting at 3600w it says 48.6mph/78.3kmh.
40mph/60kph is what my legs can take me up to with a sprint with a bbs02 assisting me, and my toothpick legs certainly don't put out even 1kw.
Couple of problems there. First, a 72V e-bike with motorcycle wheels and tires isn't anywhere close to the efficiency or weight of a normal MTB, and most e-bikers set up a riding position that increases comfort and reduces efficiency. So used default value for a roadster bike and turned up the weight. Second, our median body weight here (e-bikers, not cyclists) is rather robust, and I assumed 100kg accordingly in the absence of better data.

As I already pointed out, 3600W from the battery equals 3000W or less (likely much less) at the wheel.

I don't dispute that the OP might be getting 40mph now. But I doubt that lowering his torque per amp will help him get more speed.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

krombopulos_michael   1 mW

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Re: speed difference between turn counts

Post by krombopulos_michael » Jul 19 2018 8:43pm

Tommm wrote:
Jul 19 2018 12:18pm
Chalo wrote:
Jul 19 2018 11:37am
Tommm wrote:
Jul 18 2018 10:33pm
He is pushing 3.6kw, 40mph/60kph is nothing for that amount of power.
My quick check using the Kreuzotter speed calculator suggests that 3600W of mechanical power to the wheel would only result in 42mph on level ground. So the fact that he's getting 40mph means he's doing really well with what is optimistically about 3000W after efficiency losses.

In this case, a faster winding would result in lower top speed unless there were more current available to push it.
For me on mountainbike setting at 3600w it says 48.6mph/78.3kmh.
40mph/60kph is what my legs can take me up to with a sprint with a bbs02 assisting me, and my toothpick legs certainly don't put out even 1kw.
krombopulos_michael wrote:
Jul 19 2018 10:49am
My controller has both a flux weakening and overspeed programable options. Right now the 3rd power toggle on my throttle is programmed for 110% speed and 100% current. I’ve never messed with the flux weaking parameter though because I’ve never been sure what it does. Could anyone describe what flux weakening actually does instead of saying that it increases top speed and decreases effeciency? By how much does flux weakening increase your top speed and how bad is it for the battery(how many more watt hours do you burn through)? Also what XPD program parameters should I be using to get the max speed out of my motor given that I only have max 84V to work with. If I can get my 4T motor near 48mph by reprograming the controller and adding ferrofluid to motor then I’ll be satisfied for now.
A lot of smarter people than me have wrote what it does on this forum, you can look it up, basically, if you are RPM and not power limited at the top speed (from my calculations for arguments sake let's assume it is the case(it is)) flux weakening will change the the signals sent to the motor along with dumping even more amps into it, it will help you reach the power limit instead of the RPM one.
For example, if you have a motor geared for 25mph top speed, you will be using just 5A at top speed even with a 8A controller and battery. With flux weakening if you gain 20% RPM, a usually attainable number, you will go 30mph and draw ~8A.
I have 2 questions for you:
1) What set-up and controller programming details do you use to achieve 48mph?
2) How are you achieving 40mph with a bbs02 on a flat street?

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Re: speed difference between turn counts

Post by Tommm » Jul 19 2018 9:21pm

krombopulos_michael wrote:
Jul 19 2018 8:43pm
I have 2 questions for you:
1) What set-up and controller programming details do you use to achieve 48mph?
2) How are you achieving 40mph with a bbs02 on a flat street?
2, I achieve it with a carbon FS bike(not important), slick, non knobby tires(very important) with above average pressure(very important). Of course, this is a sprint, so it is a max speed run and not sustainable for more than 20s. Average young people can momentarily put out 600-800w in these cases, the bbs doing around 1200. You can check http://www.kreuzotter.de/english/espeed.htm with 2000w.

1, You wrote you have 100% current and 110% speed setting now? Can you find what are the max settings of these fields? Are you already doing 110% speed now for the 40mph? You could try 125% speed and 100% current at first. Btw, you can do short tests with the wheel in the air, you might hear weird sounds but that only happens without load.

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Re: speed difference between turn counts

Post by MadRhino » Jul 20 2018 12:01am

What advantage would you have to do 5 more Mph, if it is taking you forever to get there because you have no more acceleration power, and once you attain it you have to slow down right away. Your battery is not up to the task. It can’t feed more power that you have now. You have a reliable setup, that is giving you the performance that you can expect from your actual battery. Enjoy its reliability as it is, until you can upgrade. Trying to push the horse faster than it is fit to run, is a good way to end up walking.
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Re: speed difference between turn counts

Post by icherouveim » Jul 20 2018 2:12am

When I travel with 75 km/h on a flat road without strong wind my adaptto controller draws about 3000-3500W.
I have a Flux Beta ebike with 2kWh battery. I always wear helmet and jacket so the total weight is a lot.
So even if you increase over speed 20% to achieve your desire speed it will be overkill for your battery.

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