Leafmotor hub identification

[KYDave]

New to the Sphere here, arrived looking for Leafmotor info as I found a box of discarded controller hardware and two wheels by the side of the road (really!). After some reading here, have come to understand why they may have been thrown out. Both wheels are new, some packing material still attached. Have powered up both wheels, one runs but sounds like loose magnets or other scraping/friction inside, indicates max ~50kmh at ~48V. Other seems OK, indicates max 80kmh at ~48V. No part number of any kind visible on either hub. Controller is LBC481850, display is S830.

My questions:
1. Can I determine which hubs I have by electrical measurement, or are there numbers inside..?
2. Is it worth it to try to repair / re-epoxy magents that come loose.
3. Any info on general disassembly of the leafmotor hub.

I'm an EE with a lab full of gear, familiar with BLDC motors, and used to having 'real documentation'. This leaf stuff is pretty much the definition of 'black box'...

Thanks for any insight..!

_Dave

 

[amberwolf]

You won't find "real documentation" on pretty much any ebike anything, with the possible exception of open-source-developed things (mostly controller/display software around here). "Black box" usually implies the intention to hide what's inside, how it works, etc...but with this stuff, it's more like they just DGAF enough to write it down.


There is a long-running thread about the Leaf hubmotors over here if it's helpful:

Leaf / leafmotor / leafbike high efficiency 1500w motor

It's that time of year that i throw money at a new ebike product and test it to see if it lives up to the hype.. A couple members here mentioned that a few companies were offering 1500w rated hub motors for sale and i had to investigate. reference threads: Ebikeling "wide" 1500w kit Curios...

endless-sphere.com

About the only thing you might find inside for markings are sometimes a possibly-legible marker scrawl of the winding number...

"worth it" regarding any repair of them depends on what you value your time at vs the cost of a new motor that is pre-determined (by you) to fit the usage you intend for it.

If you don't have a specific usage in mind and just want to see what you can do with one, a magnet repair is generally easy; there ahve been a few threads / posts showing some methods for it (a fixture of some kind is usually necessary to secure them into place correctly against the forces they exert--3D printers make this easy enough to create, or woodworking, etc).

If there's damaged windings, then unless you just want the experience, it's way faster and cheaper to buy a new motor.

 

[neptronix]

How much do the wheels weigh? if 18lbs, you may have a 35mm.
No markings or numbers anywhere huh?
Pictures of the hub would be helpful. Especially one that displays the width.
leafmotor may also publish diagrams and you could break out a ruler and figure it out.

The stock controllers are blah, replace with something nice!

 

[KYDave]

Thanks for the info, I've been working through the posts and absorbing slowly... I decided to set the wheels up on a stand and do some measurements to get some idea of Kv and Kt. The one wheel I thought had loose magnets was actually ok, it was my stand out of alignment. So the first thing was to look at the hall output and try to get a pole count. I came up with 23 cycles per revolution, so for rpm that looks like Hz x 2.609 to get rpm. I spun the wheel with a rubber sanding disk in a drill and looked at the open circuit voltage of one phase, and the frequency of one hall sensor.

The first wheel gave me 23.68 Vrms, converting to peak, x 1.414 and we get 33.48 Vpk. Frequency was 165 Hz, so 430.5 rpm. Kv works out to 430.5 / 33.48 = 12.86

I also did a measurement with the controller hooked up at 60 VDC, full throttle, and measured average current and speed. For that setup I measured 302 Hz, 2.27 Amps. That yielded a sped of 788 rpm, Kv of 13.1, power of 136 Watts.

I measured breakaway torque with a string and digital scale with 3 amps on one phase. I made several pulls and averaged the result. This is a bit of a hack, but here are the numbers. The rim was 71.26" in circumference, so we have 11.34" moment arm. The force average was 32.12 oz. so torque came to 364 oz-in at 3 amps, so Kt of 121 oz-in / Amp.

While I had the 3 amps on the phase winding, I checked the voltage at the wire terminals and had 272.4 mV, so phase resistance was 0.905 Ohm.

I did the same method on wheel #2

Both wheels seem to be nominally 24" size, 16.26 pounds

Here is a summary:

Wheel #1
Kv open circuit 12.86
Kv with controller 13.1
Max rpm @60V 788
Kt 121 oz-in / Amp
Power @ wot 136W
Phase resistance 0.905 Ohm
Hub stator diameter ~8.77"
Rim width inside 0.978" outside 1.25"
Rim root diameter 22.68"
Rim height 0.425"
Has freewheel, 35x35mm cassette spline, ~5" axle width

Wheel #2
Kv open circuit 8.7
Kv with controller 9.08
Max rpm @60V 545
Kt 167 oz-in / Amp
Power @ wot 76.8W
Phase resistance 0.1524 Ohm
Hub stator diameter ~8.77"
Rim width inside 0.735" outside 0.95"
Rim root diameter 22.68"
Rim height 0.453"
No freewheel, ~4" axle width

Controller was Leaf LBC481850, display was S830

This was my first foray into this sort of investigation, feedback on methods and math appreciated...

_Dave