Motor won't provide power

[John_S]

I have a problem with the motor on my converted bike, which is a 48v rear Q128h that I've been running sensorless. The motor won't provide any power. The LCD switches on, and when I turn the throttle the motor provides tiny glimpses of power every couple of seconds, but it won't start. The pedal assist doesn't work at all.

There is no error message on the LCD. Oddly, when I try the throttle or pedal assist, the LCD is displaying wattage used as if the motor is actually working normally. When I reverse the bike, there is a lot of resistance and juddering made by the motor, and this occurs both when the motor is connected to the controller and when it is not. This resistance is definitely much stronger than the small amount of resistance that was present when reversing the bike before the problem occurred, the latter of which I understand to be normal.

The problem occurred suddenly on a ride yesterday. The power just stopped. I'm not aware that I was doing anything wrong to trigger the problem.

I know the problem must be the motor because I have a second electric bike which I connected the faulty motor to in order to test it, and the motor still didn't work. I also tried connecting the motor of my second bike to the controller of the affected bike, and it worked normally, which means the controller must be alright.

Is anyone able to tell me what the cause of the problem might be and how I could go about fixing it? Thanks.

 

[Woosh]

your controller may have died.

 

[John_S]

your controller may have died.

I was able to determine that the problem is with the motor as explained in my above post. I don't know what the specific problem could be though.

 

[Woosh]

how many pins on your motor cable? 3, 6 or 9?

if it's 3 or 6, you don't have Halls.
If 9 then you need to check the Hall sensors first.
After that, you need to check the coils.
Set the volt meter to 20V, spin the motor. You should see some voltage between 2 pins of the 3 phase wires / fat pins.

 

[Nealh]

The issue may be a stuck/damaged clutch, could be the nylon gears or one of the 3 small clutch springs. Until the motor is opened you won't be able to see the issue.
Also check the motor cable for damage where it enters the axle.

Heath leverage tool for side plate opening of a Q128c, a case of utilising scrap laying about.
Anti c/w to undo.


Planetary gears under clutch.


Clutch plate above planet gears.
Note on the peripheral edge the 3 clutch mechanisms, the springs are housed in side the body, The pins retaining them are just visible, can be fiddly getting all 3 back in.