Large drone motor for go kart

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skyeg3   1 W

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Large drone motor for go kart

Post by skyeg3 » Sep 27 2019 12:50am

This is theoretical for now and cost prohibitive but... If I were to want to use this motor: http://store-en.tmotor.com/goods.php?id=891 on a go kart... what controller would I use first of all. Would I need the esc? I'm unfamiliar with the drone world. Any other problems I wold run into? Seems like a pretty badass build idea to me.

Upperfoot   10 W

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Re: Large drone motor for go kart

Post by Upperfoot » Sep 27 2019 7:15am

A problem with RC motors is the lack of torque, they focus on RPM primarily, if it cant provide enough torque you will need to gear it or slap a torque converter on it otherwise it will have trouble moving and will likely overheat.

Look at a Motenergy motor, they are far cheaper and more suited to the task

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Re: Large drone motor for go kart

Post by skyeg3 » Sep 27 2019 10:52pm

Did you click on the link?

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amberwolf   100 GW

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Re: Large drone motor for go kart

Post by amberwolf » Sep 27 2019 11:07pm

The only "definite" info I found about a motor on that link is:
U15XXL KV29

• Big Power
• Matched Propulsion solution
• Stable & Reliable & Safe
(complete quote of entire page is below my post)

There's no specifications about it at all, no physical size, kV (though there's some numbers with KV after them, no way of knowing if that *is* the kV), current capability, power ratings, max RPM, etc.


However, in general these are meant for thousands (or more) of RPM, which means you need quite a lot of reduction between it and your wheel--possibly multiple stages, depending on the wheel RPM you're after.

Often enough, the reduction mechanism adds enough cost, weight, volume, and/or inefficiency that it's cheaper and easier to go with larger lower-RPM motors.




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John in CR   100 GW

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Re: Large drone motor for go kart

Post by John in CR » Sep 28 2019 1:16am

On top of no technical specs of significance, they weren't hesitant in the least to put a crazy high price. Spend money on dual battery packs, so you can swap out between races and charge the other. I'd suggest using a proven traction motor instead. The problem with a drone motor is that it's designed to have tremendous continuous air flow over it from the prop, so it will suffer heat problems long before getting to the same power you could when used on a drone.

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Re: Large drone motor for go kart

Post by Hillhater » Sep 28 2019 3:50am

amberwolf wrote:
Sep 27 2019 11:07pm
The only "definite" info I found about a motor on that link is:
U15XXL KV29

• Big Power
• Matched Propulsion solution
• Stable & Reliable & Safe
(complete quote of entire page is below my post)

There's no specifications about it at all, no physical size, kV (though there's some numbers with KV after them, no way of knowing if that *is* the kV), current capability, power ratings, max RPM, etc.
You are losing your touch AW.. :wink:
There is a tab on that page with full specs, dimensions, performance tests, temps, etc, etc,....quite extensive actually.
And yes its a 29 KV motor that has a 28 kW max rating and 75 Nm of torque.
Its peak of approx 2500 rpm is very low for a kart., requiring almost a 1:1 drive ratio..( most karts run 3:1.- 6:1 ratio depending on the track.
There are 2 other smaller motors linked , different kv, also with full specs .

http://store-en.tmotor.com/goods.php?id=891
This forum owes its existence to Justin of ebikes.ca

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Re: Large drone motor for go kart

Post by amberwolf » Sep 29 2019 12:55am

There's no tabs or any other info available on the page I get when I visit that link. Only what I quoted there, plus some pics of that motor and a bunch of unrelated stuff not part of the motor.

skyeg3   1 W

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Re: Large drone motor for go kart

Post by skyeg3 » Sep 29 2019 1:30am

A photo to guide Amberwolf and John in CR, our beloved senile friends..
amberwolf.JPG
amberwolf.JPG (82.76 KiB) Viewed 1709 times
@hillhater :bigthumb:

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amberwolf   100 GW

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Re: Large drone motor for go kart

Post by amberwolf » Sep 29 2019 2:03am

That isn't a clickable link on the page I get when I visit the link. It's just a word on the page. Why, I don't know--maybe it's written such that it's incompatible with my browser, but either way, I can't access that information, and has nothing to do with senility.

You might want to consider things like that before calling names.

Or even better, you might instead actually place all the relevant information and specifications about something you want to ask about *in your actual post*, so that anyone that can see the post can see the information.

Then you can get help from anyone with knowledge about the topic, evne if they can't access the site linked to.

John in CR   100 GW

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Re: Large drone motor for go kart

Post by John in CR » Oct 02 2019 9:32pm

skyeg3 wrote:
Sep 29 2019 1:30am
A photo to guide Amberwolf and John in CR, our beloved senile friends..
Senile...LOL! You're the one who fell for a load of horseshilt. My hubmotors would make better drone motors despite the extra weight. For the only listing for power those scammers show input power, and then they were stupid enough to show torque, rpm, and temp info, because that info exposes how bad that motor is. Power = Nm of torque X rpm X 0.1047 . An easy bit of number crunching shows why the motor runs at those temp levels and low power compared to the max power they claim, despite being in a strong flow of air for cooling from the propeller. That's because the best efficiency that motor could manage even swinging the light prop is just 84%. They tried to hide the poor efficiency by redefining efficiency as grams per watt of input.

In comparison, at those torque and rpm levels my hubmotor would see a relatively easy load and run at over 94% efficiency. Loading mine down with a bigger prop to require 100Nm of torque would put it right at peak efficiency of almost 96% at the well over 100V required to turn it at that rpm. Whine and cry foul all you want about the over double my motor weighs, and you'd be forgetting about the extra battery weight running that motor would require. Plus the far greater risk of failure running those high temps.

The motor has a nice low winding resistance, so it's low efficiency at cruising rpm must be due to running at too high a voltage. The slot/pole count is too high, probably combined with cheap laminating steel. Drop the voltage to 50V or so and the efficiency should go up to more useful levels and end up with about a 7-10kw motor... For that larcenous price, no thanks!

Senile my A$$ !

skyeg3   1 W

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Re: Large drone motor for go kart

Post by skyeg3 » Oct 02 2019 11:37pm

All in good fun...

John, that is interesting about the efficiency number crunching. I wonder how they are even measuring torque with a propeller on it... isn't torque and power usually calculated by accelerating a mass?

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Re: Large drone motor for go kart

Post by amberwolf » Oct 03 2019 12:24am

A propeller is a mass, as is the air it has to move. How specifically they measure the torque doing that I don't know.

But they probably measure it using a more conventional method, of some sort of dynamometer, or a load-lever like Justin LE used in some testing.

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Re: Large drone motor for go kart

Post by Hillhater » Oct 04 2019 7:01pm

skyeg3 wrote:
Oct 02 2019 11:37pm
John, that is interesting about the efficiency number crunching. I wonder how they are even measuring torque with a propeller on it... isn't torque and power usually calculated by accelerating a mass?
Torque can either be measured directly as AW says, using a dynomometer of various forms,...
....or it can be calculated as john said, from the voltage, current, rpm, measurements...

Use the Volt and Amp measurements to find the motor power (Watts)
Divide the number of watts by 746 to get the horse power rating of the electrical motor....
..divide the watts by 746 to get the equivalent horsepower .
Multiply the horsepower by 5,252 using a calculator.
Divide the answer by the motor's rpm to get the measurement of the torque in pound-feet.
If needed, convert to Nm by multiplying the lbft by 1.36.
This forum owes its existence to Justin of ebikes.ca

skyeg3   1 W

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Re: Large drone motor for go kart

Post by skyeg3 » Oct 07 2019 12:15am

Back to the original question - Does anyone know what controller could be used with this motor?

Bluefang   10 kW

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Re: Large drone motor for go kart

Post by Bluefang » Oct 10 2019 10:33pm

Kelly controllers KLS range would be good assuming they can match the high E-rpm of the motors if you want them quiet. Otherwise the KHB range would be better for price, will have a loud whine to the motor usually.

Seriously tho, that price is frocked. Try https://frchobby.en.alibaba.com/?spm=a2 ... 2c9a2vnlgf

They sell on Aliexpress. Found them when i was looking for a dual conter-rotating propeller setup. Nice stuff and cheap HUGE propellers. They are missing the 1.8m one to work with the dual prop system tho.
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district9prawn   100 W

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Re: Large drone motor for go kart

Post by district9prawn » Oct 11 2019 6:54am

The whopping pole count of 42 means you need a 50000 erpm capable controller just to spin the shaft at 2500 rpm.

If you go through some old posts here you will find some tests on large Hobby King outrunners demonstrating extreme core losses at high speed. No idea if this is the case with T-motor but there is a big efficiency price to pay for the high pole count and thin, weight saving rotor iron.

As others have pointed out there are some cheaper proven options for a motor this size.
Neu 8057 6kW left hand drive hardtail with 18 fet Vesc: viewtopic.php?f=6&t=96754

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Re: Large drone motor for go kart

Post by HK12K » Oct 16 2019 10:45am


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Re: Large drone motor for go kart

Post by madin88 » Oct 16 2019 1:17pm

skyeg3 wrote:
Oct 07 2019 12:15am
Back to the original question - Does anyone know what controller could be used with this motor?
VESC 75/300

https://www.youtube.com/watch?v=fbK2dcoYS7g
In the vid above the developer says that it can handle a motor with 1µH inductance, which would be similar as if it would drive current through a one foot long wire :mrgreen: , and it should be able to do 100k ERPM in FOC.
So it should have no problem driving mentioned motor.

Do you have any special requirements on space or weight?
Because if not then i would agree to everyone else here and take a true EV motor which has hall sensors and a sealed housing as for instance and in terms of peak power more mass is also a good thing.

It is always fun to read about John and his Hubmonster. It is a heavy beast and old (low pole count which needs alot of iron), but it still seems to be one of the best and highest efficient motors we know about these days :)

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