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Jun 09, 2019, 10:11 AM
Master Prop Breaker
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Just ended up with a pile of these large brushless scooter motors.


Look what I just acquired. The electric scooter rental craze is flooding cities but are being abandoned so cities are auctioning off abandoned or broken ones. Scored 10 for $100 today. Each has 60 18650s! Was surprised at the quality of the motor, definitely not for parkflyers. Not sure of kv as is but its probably very low. Is there any application on big planes with a rewind. Ideas on a pattern for winding, ABC?
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Jun 09, 2019, 02:02 PM
Registered User
Nice! How much does the stator weigh? That ought to allow some estimation of the potential power, assuming a normal rotor to be around half of the stator weight, and total power to weight ratio 3-4W/g. I'd also be curious to know the stator dimensions.
Jun 09, 2019, 03:33 PM
Master Prop Breaker
Thread OP
Quote:
Originally Posted by dekutree64
Nice! How much does the stator weigh? That ought to allow some estimation of the potential power, assuming a normal rotor to be around half of the stator weight, and total power to weight ratio 3-4W/g. I'd also be curious to know the stator dimensions.

Good idea, weighs 1.33kg. Converting from my imperial ruler 4.5" or about 115mm

Jesus, the watt per gram estimate is nuts even on the low side! Of course cooling would need to be added
Jun 09, 2019, 03:45 PM
Master Prop Breaker
Thread OP
BTW, these scooters have a range of 28 miles, speed of 23mph(speed limited as a rental to 15mph). Not a kids toy. Wash DC is just chock full of them. Called dockless scooters, rental companies basically charge them at night and set them free during the day. A user rides to destination and leaves it, another picks it up and does the same. Scooters are found with GPS for user and charging pickup.
Jun 09, 2019, 03:53 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
Have you determined their Kv constant?
How many stator- and magnet-poles? Two magnets per magnetpole?

Vriendelijke groeten Ron
Jun 09, 2019, 04:18 PM
If it flies, I can crash it.
rocketsled666's Avatar
23 MPH * 5280 feet per mile / 60 minutes per hour = 2024 feet per minute = 24288 inch per minute.

I'm going to guess the wheel is 5" in diameter, so that's about a 16 inch circumference.

24288 inch per minute / 16 inches per rev = 1518 RPM.

Assuming the battery pack is set up for 40V operation, that's a KV of about 40. Actually a bit higher since under load the motor isn't going to run at its KV speed. Figure 50 for a more realistic KV. But that's still too low for RC flight use (though it develops enough torque you could probably gear it up quite a bit and spin a prop pretty fast).
Jun 09, 2019, 06:12 PM
Master Prop Breaker
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Quote:
Originally Posted by rocketsled666
23 MPH * 5280 feet per mile / 60 minutes per hour = 2024 feet per minute = 24288 inch per minute.

I'm going to guess the wheel is 5" in diameter, so that's about a 16 inch circumference.

24288 inch per minute / 16 inches per rev = 1518 RPM.

Assuming the battery pack is set up for 40V operation, that's a KV of about 40. Actually a bit higher since under load the motor isn't going to run at its KV speed. Figure 50 for a more realistic KV. But that's still too low for RC flight use (though it develops enough torque you could probably gear it up quite a bit and spin a prop pretty fast).
Rocketsled=rocket scientist! The wheel is actually 8", I was measuring the stator, speed is limited by FW though can be hacked for more but regenerative braking(cant be disabled) tends to fry the ESC at those speeds when you let off the throttle. I counted 24 poles, haven't done magnet count yet. No drill press here but I suppose I could use a corded drill (keeps speed constant), tach and a multimeter to test for existing Kv. Kv is much too low for anything but huge props still may be too low. Tire is easily removable, mounting may take some thought, Prop adapter is going to be a challenge as well. Have a 33% H9 edge 540 that I would like to electrify.
Jun 09, 2019, 06:24 PM
Master Prop Breaker
Thread OP
I have no issue with rewinding. Raising KV with fewer turn of thicker gauge wire wouldn't be super hard. especially given its not glued in and the existing end plates are provided. Im surprised at its quality, definitely, some thought went into its design. Almost like the designers took ideas from RC forums. Lol!
Jun 09, 2019, 06:44 PM
homo ludens modellisticus
Ron van Sommeren's Avatar
Hold yer horses, maybe it's delta configuration. Then you could switch it to star.

Vriendelijke groeten Ron
Last edited by Ron van Sommeren; Jun 10, 2019 at 09:20 AM. Reason: Originally: ... maybe it's in star configuration ...
Jun 09, 2019, 07:21 PM
Master Prop Breaker
Thread OP
Quote:
Originally Posted by Ron van Sommeren
Hold yer horses, maybe it's star configuration. Then you could switch it to star.

Vriendelijke groeten Ron
Hold yer horses. Lol! You mean it could be delta now switch to star for higher kv. Gotta check that out in a bit, motor is upstairs near my wife/roommate. I avoid unnecessary contact at all costs. Yeah, its that bad
Jun 09, 2019, 09:26 PM
Registered User
Awesome! Would you be willing to sell me some of them? I need at least two, but three or more would be nice in case I screw one up. If not I can just keep my eyes peeled for similar deals.

By rocketsled's calculations adjusted for 8" wheel, that's about 966RPM. Most likely you could run it over 3x that fast for spinning a propeller. And higher torque too, if you can get some airflow through the rotor.

It will indeed be a challenge to adapt it for propeller spinning, though. I think you'll need to add a motor mount to the stator, and make a new bottom plate for the wheel with a large diameter bearing so you can fit the motor mount through it. Something like this: https://alienpowersystem.com/shop/br...or-50kv-5000w/
But in that case your RPM limit may be determined by the large bearing's rated speed.
Jun 10, 2019, 01:38 AM
Registered User
Skylar's Avatar
Have you noticed that the name SEGWAY on the castings?

Interesting...
Jun 10, 2019, 07:10 AM
Master Prop Breaker
Thread OP
Quote:
Originally Posted by Skylar
Have you noticed that the name SEGWAY on the castings?

Interesting...
Yes, these are $800 -$1000 e- scooters. DC is flooded with 10,000 of them in some mad Max experiment. Their meant to fill the last mile transportation issue which they work great for but their littered everywhere! $1 to start, 15 cents a min after. Check out Segway Ninebot ES4
Last edited by chrisbarth; Jun 16, 2019 at 01:44 PM.
Jun 10, 2019, 07:16 AM
Master Prop Breaker
Thread OP
Quote:
Originally Posted by dekutree64
Awesome! Would you be willing to sell me some of them? I need at least two, but three or more would be nice in case I screw one up. If not I can just keep my eyes peeled for similar deals.

By rocketsled's calculations adjusted for 8" wheel, that's about 966RPM. Most likely you could run it over 3x that fast for spinning a propeller. And higher torque too, if you can get some airflow through the rotor.

It will indeed be a challenge to adapt it for propeller spinning, though. I think you'll need to add a motor mount to the stator, and make a new bottom plate for the wheel with a large diameter bearing so you can fit the motor mount through it. Something like this: https://alienpowersystem.com/shop/br...or-50kv-5000w/
But in that case your RPM limit may be determined by the large bearing's rated speed.
I'll see what I can do, got a good hookup on them. Beautifully engineered, thin lams, small airgap. Something like this built for an airplane would be $$$.

Trying to get a batch of more powerful motors from another scooter brand. I have one, yet to pry it open, looks like a PIA to do.
Last edited by chrisbarth; Jun 10, 2019 at 12:26 PM. Reason: Refine wording.
Jun 10, 2019, 09:14 AM
homo ludens modellisticus
Ron van Sommeren's Avatar
Quote:
Originally Posted by Ron van Sommeren
Hold yer horses, maybe it's star configuration. Then you could switch it to star. ...
Oops, should be maybe it's in delta.
Then switching to star configuration would divide Kv by factor √3. (Nothing new for you I assume).
At the same time multiplying Kt, torque for given current, by same factor.

Kv × Kt = 1, or Kt = 1/Kv
All in SI-units: rad/s/V and Nm/A.

Quote:
Originally Posted by chrisbarth
... No drill press here ...
But you can measure battery voltage and rpmno_load.
Can you measure stator diameter and thickness?
Lamination thickness?

Quote:
Originally Posted by chrisbarth
... yet to pry it open, kinda a PIA to do.
Don't force it, just take a bigger hammer.

Vriendelijke groeten Ron
Last edited by Ron van Sommeren; Jun 10, 2019 at 09:40 AM.


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