Q128 motor swap

djah

Pedelecer
Apr 24, 2018
74
3
54
Ireland
Hello
I received a replacement motor hub from Bmsbattery as the original failed after 200kms.
I think I can just disassemble both hubs and swap the internal parts rather than re-lacing the new hub into the wheel.
Does anyone know if the 9 pin waterproof connector will pass through the axle or do I have to de-solder the cable from the inner parts?
Many thanks.


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Woosh

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May 19, 2012
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I think I can just disassemble both hubs and swap the internal parts rather than re-lacing the new hub into the wheel.
yes, that should work.

Does anyone know if the 9 pin waterproof connector will pass through the axle
the 9-pin motor cable goes through the axle like in your own motor.
 

wheeliepete

Esteemed Pedelecer
Feb 28, 2016
2,047
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Devon
The axle and cable are part of the internals of the motor, so no need to remove either, just remove old core and replace with new. Depending which model of Q128 you have, you may need to make a tool to open the casing.
 

djah

Pedelecer
Apr 24, 2018
74
3
54
Ireland
Thanks for the replies.
I don’t have the motor to hand at the moment but going from memory the 9 pin connector just about passes through torque washer. The torque washer is the same width as the flat part of the axle. This is why I was unsure, but thanks for clearing that up.

Edit: Sorry, should have read your post properly. The axle is part of the internals.

I have made a tool already. Hopefully it will work.
 
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jarob10

Esteemed Pedelecer
Jan 22, 2017
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Uk
4D017962-63E2-4F6F-9169-02786BCA97DA.jpeg
I have made a tool already. Hopefully it will work.
The end cover from your old motor can be repurposed as a removal tool. A vice or even large stilsons on the threads can then get decent purchase.

Keep the remains of your old motor for spares
 

djah

Pedelecer
Apr 24, 2018
74
3
54
Ireland
Thanks for your reply. I managed to swap the motors. The process was fairly straight forward.
However my wife and I went for a spin today and this time here motor failed. I’m getting “info 3” error. Both failures occurred on steep climbs in assistance setting 5(max setting).
So I took her motor apart to test the hall sensors.
Does anyone know should I be getting the same resistance values on the legs of the 3 sensors?(are the 3 sensors identical? If I’m getting different values on one of the 3, is it faulty?)



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Woosh

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May 19, 2012
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you can only detect short-circuits by measuring resistance, not conclusive when the Hall sensors are working. You need to connect the motor and switch on the electrics. A good Hall sensor will change from 0V to 3.25V between pin 2 (middle) and pin 3 (right) when the magnets move in front of it.
 

djah

Pedelecer
Apr 24, 2018
74
3
54
Ireland
Thanks very much Woosh. Any guidance on how to do this? I have the 9 pin waterproof connector. I don’t know where to take the measurements from. I am an electrician with basic electronic knowledge. I would have assumed that all three hall sensors should give the same resistance values?


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Woosh

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May 19, 2012
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it's very easy as you have already got the motor lid open.

First take a look at the functional block diagram of an SS41 Hall sensor:



Connect the 9-pin motor cable. Switch on the LCD.

Pin 2 is the middle pin of your Hall sensor, that's the ground pin.
tLooking at your picture, pin 3 is the right pin of the sensor. Refer to the diagram for confirmation. The output (pin 3) is what we call an open collector output, there is an NPN transistor connecting it to ground when activated. A pull up resistor on the controller side completes the circuit.
That's why you can't diagnose by measuring the resistance of the circuit when the motor cable is disconnected, you need the pull up resistor and a voltage to make sense.
Put the motor axle into a table vice to make sure that everything is secure before you connect everything up and switch on the LCD.
Set your tester to 10V, connect the black wire on your tester to pin 2 and the red wire of your tester to pin 3. You want to measure the voltage across pin 2 and pin 3 of the sensor.
Ask a friend to turn slowly the wheel backward to engage the rotor while you watch the voltage at the output pin3. You should see it changing from 0V to 3.25V then back to 0V when the magnet passes in front of the sensor.
 

djah

Pedelecer
Apr 24, 2018
74
3
54
Ireland
Hi Woosh. Thanks again for your help. I’m getting 5.1V between pins 2 and 3 but it’s constant. It doesn’t go to zero as the wheel is rotated. It’s the same for all 3 sensors. Any ideas?


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Last edited:

Woosh

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May 19, 2012
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Hi Woosh. Thanks again for your help. I’m getting 4.6V between pins 2 and 3 but it’s constant. It doesn’t go to zero as the wheel is rotated. It’s the same for all 3 sensors. Any ideas?


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You are measuring between ground and Pin 1 (Vcc).
try the other leg, between middle and left leg instead of between middle and right.
 

Woosh

Trade Member
May 19, 2012
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did you see the magnets move slowly when you turn the wheel?
If they don't move, try turning the wheel in the opposite direction.
 

super josh

Finding my (electric) wheels
Oct 2, 2018
16
3
58
I know that I'm stating the obvious, but you have installed the PCB back in the motor so that the magnets are energising the hall effect?

Cheers,
Josh
 
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djah

Pedelecer
Apr 24, 2018
74
3
54
Ireland
Yeah Josh thanks.
PCB back in place
Getting funny readings 4.5V between 1 and 2. Then 5.1V between 2 and 3. The controller then seems to go in to “limp mode” and then I get 1.5V between 1 and 2 and 2.3V between 2 and 3. This is all with the PCB in place and the wheel rotating.
So just a question. Are these the only electronics that can fail?
If so, if I was to replace all four hall sensors, should this rectify the problem?
Thanks guys.


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Woosh

Trade Member
May 19, 2012
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where do you live?
If you could bring it to Southend, I can test your wheel for you for free. It's a 5 minute job.
 

Nealh

Esteemed Pedelecer
Aug 7, 2014
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Testing halls is quite simple no need to open the hub to check them, if you are able to access hall wiring connector from the controller.
Connect everything up and turn the battery on, place one probe on the black and in turn the red probe on Blue, green & yellow. If having difficulty getting a contact use a two pins or needles to access the contacts in the connector.
Slowly turning the wheel backwards you should see the halls open and close(as the magnet passes) via the voltage reading, voltage should be the same (or very similar) on all three readings and you should see 0v - 4 or 5v ( if the wheel is turned to fast you will see an average of 2 - 2.5v).
Any reading not showing 4 or more volts means a duff hall.
 
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djah

Pedelecer
Apr 24, 2018
74
3
54
Ireland
Thanks for the offer Woosh. I live in Ireland.
I think I could have a problem with the controller now too. The display won’t switch on. I guess I’ll have to wait for BMSBATTERY to come back to me. Fingers crossed.


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