What motor do I need for 26Kw?

Sparky123

1 mW
Joined
Dec 31, 2021
Messages
12
I’m building a 26Kw ebike that run off of about 360 battery amps at 72v. I need to buy a hub motor but I don’t know what one will be suitable. Im looking for a 5T motor and I don’t want to spend over $500. I know that a 26Kw rated motor is overkill so what power rating should be sufficient, I don’t live in a hot climate and I might cool the motor with ferrofluid and hub sinks if i need to. I am looking at getting a qs motor of some kind, any suggestions are very much appreciated, thanks
 
E-HP said:
Sparky123 said:
I know that a 26Kw rated motor is overkill so what power rating should be sufficient

Sufficient for what?
My guess is what the minimum rated motor he can get away with without overheating all the time

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brazilianboy said:
Sparky123 said:
E-HP said:
Sparky123 said:
I know that a 26Kw rated motor is overkill so what power rating should be sufficient

Sufficient for what?
I want the smallest and lightest motor that won’t overheat or melt at 26Kw
QS273

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Yeah, that’s what I’ve been looking at, it seems like it can easily handle the power, obviously I won’t be running full throttle the whole ride
 
Are you talking about 26kw motor output or motor input power?
If you want to run it only at 72V, 26kw output is probably impossible with a qs205 or qs273 without rewinding the motor with less turns. For 26kw motor input power at 72V, a QS205 or QS273 with 3T winding could be enough.
Both motors will quickly get hot at 26kw, but the QS205 quicker than the QS273.
If you want to push 26kw through a motor with more turns, you need to go for a higher battery voltage and suitable controller.
 
hias9 said:
Are you talking about 26kw motor output or motor input power?
If you want to run it only at 72V, 26kw output is probably impossible with a qs205 or qs273 without rewinding the motor with less turns. For 26kw motor input power at 72V, a QS205 or QS273 with 3T winding could be enough.
Both motors will quickly get hot at 26kw, but the QS205 quicker than the QS273.
If you want to push 26kw through a motor with more turns, you need to go for a higher battery voltage and suitable controller.
I agree with you. But to overheat a QS273 is a hell of a task...
Also, Nobody push all that power all the time.

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brazilianboy said:
hias9 said:
Are you talking about 26kw motor output or motor input power?
If you want to run it only at 72V, 26kw output is probably impossible with a qs205 or qs273 without rewinding the motor with less turns. For 26kw motor input power at 72V, a QS205 or QS273 with 3T winding could be enough.
Both motors will quickly get hot at 26kw, but the QS205 quicker than the QS273.
If you want to push 26kw through a motor with more turns, you need to go for a higher battery voltage and suitable controller.
I agree with you. But to overheat a QS273 is a hell of a task...
Also, Nobody push all that power all the time.

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So where do you find a QS273 for less than $500?
 
hias9 said:
Are you talking about 26kw motor output or motor input power?
If you want to run it only at 72V, 26kw output is probably impossible with a qs205 or qs273 without rewinding the motor with less turns. For 26kw motor input power at 72V, a QS205 or QS273 with 3T winding could be enough.
Both motors will quickly get hot at 26kw, but the QS205 quicker than the QS273.
If you want to push 26kw through a motor with more turns, you need to go for a higher battery voltage and suitable controller.
The battery output will be 26kw. I didn’t know that the number of turns affected the motor power, surely even with only 72v with a 5T motor there is a certain rpm where it will make 26kw which would be at low speeds, right? I have seen videos of people doing something very similar and it worked out for them
 
So where do you find a QS273 for less than $500?
[/quote]
You’re right, I will probably have to spend upwards of $900 but it’s not what I originally planned
 
Sparky123 said:
The battery output will be 26kw. I didn’t know that the number of turns affected the motor power, surely even with only 72v with a 5T motor there is a certain rpm where it will make 26kw which would be at low speeds, right? I have seen videos of people doing something very similar and it worked out for them

You decided a 5T motor is what you want based on a video, but before deciding which motor? If that's the case, maybe just buy the motor from the video.
 
E-HP said:
Sparky123 said:
The battery output will be 26kw. I didn’t know that the number of turns affected the motor power, surely even with only 72v with a 5T motor there is a certain rpm where it will make 26kw which would be at low speeds, right? I have seen videos of people doing something very similar and it worked out for them

You decided a 5T motor is what you want based on a video, but before deciding which motor? If that's the case, maybe just buy the motor from the video.
The motor in the video was a 5T QS273 but I do know that I will probably want a low number of turns for most motors
 
Sparky123 said:
The motor in the video was a 5T QS273 but I do know that I will probably want a low number of turns for most motors

You won't find a motor that handles that power for $500, so you'll likely need to adjust your budget or expectations. Maybe come up with some real world specs and budget.
 
Sparky123 said:
So where do you find a QS273 for less than $500?
You’re right, I will probably have to spend upwards of $900 but it’s not what I originally planned[/quote]When building something like an electric vehicle as a hobby, always get the budget that you think you want to invest and multiply by 3. There is always something that will make you spend more than you originally planned

Keep your your expectations low and realistic about budget and you will enjoy the build more.

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Why you say it should be 5T before even knowing which motor you want??
Regarding qs273 and escpecially qs205, I guess for a 5T the winding resistance and inductance will be too high to push 26kw through it at 72V. To push more power through it you need higher voltage or less turns.
QS273 is below $500, but only without shipping, duty and taxes.

So you just need the 26kw motor input power for short peaks and don't want to go higher than 72V? With a qs205 3T and a controller that puts out a lot of phase amps this should be possible. But of course it will overheat quickly at this power. Probably already after a few full power accelerations in a row.
 
hias9 said:
Why you say it should be 5T before even knowing which motor you want??
Regarding qs273 and escpecially qs205, I guess for a 5T the winding resistance and inductance will be too high to push 26kw through it at 72V. To push more power through it you need higher voltage or less turns.
QS273 is below $500, but only without shipping, duty and taxes.

So you just need the 26kw motor input power for short peaks and don't want to go higher than 72V? With a qs205 3T and a controller that puts out a lot of phase amps this should be possible. But of course it will overheat quickly at this power. Probably already after a few full power accelerations in a row.

So the reason that I am looking for a 5T qs 205 / qs273 is because it would have more tourque at lower speeds when compared to a 3.5T motor, right? I am just a newbie with this ebike stuff and I have never heard of a motor winding affecting the power of the bike, I thought it just affected what rpm had the most power, like a gear ratio.

For example, there is this guy on YouTube called ‘Josh Street Design’ that made a 72v 12kw bike and tried both the 5T and 3.5T qs motors and had great success with both. And says that 72v is capable of any motor winding.
 
Sparky123 said:
hias9 said:
Why you say it should be 5T before even knowing which motor you want??
Regarding qs273 and escpecially qs205, I guess for a 5T the winding resistance and inductance will be too high to push 26kw through it at 72V. To push more power through it you need higher voltage or less turns.
QS273 is below $500, but only without shipping, duty and taxes.

So you just need the 26kw motor input power for short peaks and don't want to go higher than 72V? With a qs205 3T and a controller that puts out a lot of phase amps this should be possible. But of course it will overheat quickly at this power. Probably already after a few full power accelerations in a row.

So the reason that I am looking for a 5T qs 205 / qs273 is because it would have more tourque at lower speeds when compared to a 3.5T motor, right? I am just a newbie with this ebike stuff and I have never heard of a motor winding affecting the power of the bike, I thought it just affected what rpm had the most power, like a gear ratio.

For example, there is this guy on YouTube called ‘Josh Street Design’ that made a 72v 12kw bike and tried both the 5T and 3.5T qs motors and had great success with both. And says that 72v is capable of any motor winding.
I'd recommend you start small first, learn the basics then make a basic build and work your way up from there

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brazilianboy said:
Sparky123 said:
hias9 said:
Why you say it should be 5T before even knowing which motor you want??
Regarding qs273 and escpecially qs205, I guess for a 5T the winding resistance and inductance will be too high to push 26kw through it at 72V. To push more power through it you need higher voltage or less turns.
QS273 is below $500, but only without shipping, duty and taxes.

So you just need the 26kw motor input power for short peaks and don't want to go higher than 72V? With a qs205 3T and a controller that puts out a lot of phase amps this should be possible. But of course it will overheat quickly at this power. Probably already after a few full power accelerations in a row.

So the reason that I am looking for a 5T qs 205 / qs273 is because it would have more tourque at lower speeds when compared to a 3.5T motor, right? I am just a newbie with this ebike stuff and I have never heard of a motor winding affecting the power of the bike, I thought it just affected what rpm had the most power, like a gear ratio.

For example, there is this guy on YouTube called ‘Josh Street Design’ that made a 72v 12kw bike and tried both the 5T and 3.5T qs motors and had great success with both. And says that 72v is capable of any motor winding.
I'd recommend you start small first, learn the basics then make a basic build and work your way up from there

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I’ve built some ebikes before, it’s just compared to some of the absolute professional builders on this forum, I’m a newbie but I have welded together a battery before and the basic things like that
 
I recommend that you make a detailed list of exactly what you want the bike to do for you, under the specific conditions you need it to do those things.

Then go to http://ebikes.ca/tools/simulator.html and read the entire page to learn how it works and what it does for you. Then use the simulator to "build" a bike that does what you want it to do (you'll probably have to create "custom" settings for some things). Then you can locate parts that do what the parts in the simulator do, and let you build the bike you want without nearly as much guesswork, and probably with less overkill on parts and thus a lower cost to build.

Keep in mind that the simulator's built-in settings are for ebike power levels, while you are building at an emotorcycle level, so you'll definitely need to read it's instructions and experiment with it to get it to simulate what you intend to do.
 
amberwolf said:
I recommend that you make a detailed list of exactly what you want the bike to do for you, under the specific conditions you need it to do those things.

Then go to http://ebikes.ca/tools/simulator.html and read the entire page to learn how it works and what it does for you. Then use the simulator to "build" a bike that does what you want it to do (you'll probably have to create "custom" settings for some things). Then you can locate parts that do what the parts in the simulator do, and let you build the bike you want without nearly as much guesswork, and probably with less overkill on parts and thus a lower cost to build.

Keep in mind that the simulator's built-in settings are for ebike power levels, while you are building at an emotorcycle level, so you'll definitely need to read it's instructions and experiment with it to get it to simulate what you intend to do.
Ok cool, I’ll try that, thanks
 
Sparky123 said:
amberwolf said:
I recommend that you make a detailed list of exactly what you want the bike to do for you, under the specific conditions you need it to do those things.

Then go to http://ebikes.ca/tools/simulator.html and read the entire page to learn how it works and what it does for you. Then use the simulator to "build" a bike that does what you want it to do (you'll probably have to create "custom" settings for some things). Then you can locate parts that do what the parts in the simulator do, and let you build the bike you want without nearly as much guesswork, and probably with less overkill on parts and thus a lower cost to build.

Keep in mind that the simulator's built-in settings are for ebike power levels, while you are building at an emotorcycle level, so you'll definitely need to read it's instructions and experiment with it to get it to simulate what you intend to do.
Ok cool, I’ll try that, thanks

In addition to making a list of what the bike will do, you should also make a list of the build constraints, if you already have a frame picked out, like the one from your other thread. Specifically you want to make sure you have the clearance and the right dropout width, since that can impose some limitations on your choices (or if you have thru axles, etc.).
 
In addition to making a list of what the bike will do, you should also make a list of the build constraints, if you already have a frame picked out, like the one from your other thread. Specifically you want to make sure you have the clearance and the right dropout width, since that can impose some limitations on your choices (or if you have thru axles, etc.).
[/quote]
Great point, thanks for letting me know
 
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