[Solved] 250W gear hub motor stalling/juddering motion with horrible noise

[GT877]

I've just finished a custom ebike build with the objective of having very long range.
The motor is a 250w rear hub geared motor (no brand) laced into a 20" wheel and the controller is rated for 350w. The controller only has a throttle input (no PAS)
My battery is a 48v 50ah lifepo4 and is frame mounted
I've finally wired it all up and took it for a test ride but if I push the throttle gradually the motor starts turning for just a second before immediately making a very loud grinding/screeching sound and will continue like that at a very very slow speed with this loud noise (won't go any faster) until I let go of the throttle. If however I push the throttle full, the motor accelerates very quickly and seems to get past that 'cogging' stage and shoots of with consisderable speed.
I am not sure if it is a motor, controller or throttle problem.
The sound is similar to screeching bike brakes but much louder
The bike has a drop stand so I can prop the bike up and test the motor and the problem does not appear at all. I am wondering if the motor can't handle my weight (76kg)

I was also wondering does the 350w controller only draw maximum 350w from the 2400w battery so it is ok to use a battery of that capacity?

Sorry if I posted this in the wrong section!

 

[Eastwood]

Are you sure you have the right phase wire combination?

 

[GT877]

Hi thank you for your response. I believe so as the controller and motor both have the same 3 colours (blue, green and yellow)
With just the bike propped up, the motor runs absolutely great with a smooth start from the throttle and no worrying sounds so I think the phase wires are all ok. It is only when I ride the bike the problem happens.

 

[amberwolf]

Color isn't an indication of anything except color.

To get the right phase/hall combination, you either have to use the learning function of the controller if it has one, or test the various possible combinations (there are bunches of threads about that part) while monitoring current (amps) from battery to controller to make sure it isn't drawing too much even if it "sounds" right.

The wrong combo can cause all sorts of noises especially under load, draws more current than it should, and can blow up the controller or overheat the motor. It can also cause the motor to spin faster than it is supposed to be spinning (which takes more current and heats things up too).

 

[GT877]

Thanks I gave the self learning function a go and the wheel starts spinning in the right direction and then I disconnect the self learning wire and disconnect the controller. Is that correct? I did do it several times and I notice sometimes the wheel doesn't spin at all but I can hear the motor inside the hub spinning which is strange.
I took the bike down the road to test it and the problem still persists.
Shall I manually swap phase wires round instead?
I thought it was odd though that at times the motor was spinning inside the hub without the wheel turning is this a mechanical problem instead?

 

[2old]

For my admittedly unprofessional ear, it sounds like a clutch problem.

 

[GT877]

Just to add to my previous post. When using the self learn function and noticing it not turning the wheel but audibly spinning inside the hub once I press the throttle briefly it stops and then turns the whole wheel in right direction. I understand now that if the motor spins backwards it freewheels and doesn't turn the whole wheel. I will swap the phase wires around anyway and hall sensor wires to be sure but was wondering whether it is a clutch problem too.

 

[999zip999]

Hook up your hall wires the five or it could be a six plug.
Then hook up your phase wires color to color.
Try with the wheel off the ground. High population now leave the blue and swap the green and yellow wires test with wheel off the ground.
Now leave the yellow wire connected and switch the other two. Test

Now the green wire and switch the other two now grab any two wires and switch them.
This is the easiest way to see if you can get a correct phase in Hall combination.
Other than that it can get a little more complicated when switching the hall wires and then testing.
This is not using the self learning wire but you get to be the learning professor.
Good luck

 

[GT877]

Thanks for your suggestions. I have finally fixed the problem and it turned out it was the throttle! I swapped it (compact slim clip on thumb throttle) out with a different type of thumb throttle (the box style with red,yellow&green led) and no more juddering/stalling and horridly loud noises! All smooth motion as it should be.