Help! Motor hall sensor fault

[orcecaveman]

You may remember my previous posts with the suspected pedal assist sensor and control unit.
Well, we have an update and I think, A : I've learned a lot (thanks to you guys, and B: I see light at the end of the tunnel.
It's still a mystery what happened to this bike before I had it, but it seems like there were several faults.
Anyway, I've fitted pretty much everything new except the motor, and guess what? My new display indicates 'info 3' which is 'Motor hall signal abnormality'.
So, my question is... is this likely to be a new hub motor required, or can I replace the hall sensors easily? Has anybody advice or tips on what's involved please? I've no idea what make the hub motor is, but I've attached pictures of the markings
Thanks in advance for your help.

 

[vfr400]

Everything is easy when you know how and when you've practiced.

It can be a hall sensor or it can be a nicked wire, faulty joint or bad connection. It's easy to open the motor, then you can test the hall sensors directlyc to see if one or more are faulty. T might just need cleaning or you might see a cut wire.

Make sure the motor connector is all the way to the line. If you have a spare controller, you can cut off the motor connector to test the motor from the outside before dismantling the motor.

 

[orcecaveman]

Everything is easy when you know how and when you've practiced.

It can be a hall sensor or it can be a nicked wire, faulty joint or bad connection. It's easy to open the motor, then you can test the hall sensors directlyc to see if one or more are faulty. T might just need cleaning or you might see a cut wire.

Make sure the motor connector is all the way to the line. If you have a spare controller, you can cut off the motor connector to test the motor from the outside before dismantling the motor.

Thanks for the quick reply. I'm sure everything is ok at the controller end of the cable, so I'll open up the motor and have a look. It would be nice to think that they need cleaning.
Whereabouts would it be likely to need a clean?

On a couple of tries the wheel did seem like it tried to turn a minute amount on the throttle.

Frustrating, as I feel I'm close to getting this thing working!

 

[vfr400]

When dirty water gets in, you can see where all the corrosion and crystals are. Different motors have different ways the hall sensors are mounted. When you've opened the motor, take some photos of you're not sure how to test.

 

[orcecaveman]

When dirty water gets in, you can see where all the corrosion and crystals are. Different motors have different ways the hall sensors are mounted. When you've opened the motor, take some photos of you're not sure how to test.

Thanks, that's exactly what I intend to do. Are the hall sensors most likely to be glued in place?

 

[vfr400]

Likely, but by no means certain. Even if they are, they're easy to replace. When touching them, be very careful with the legs, which break too easily.

 

[orcecaveman]

Mornin!
I've split the motor and I think I've spotted the issue. Some of the wires connecting the hall sensors have been stripped of their insulation.
Could it have been caused by rubbing on the inside of the hub?
I'm thinking of sleeping with some very small diameter heat shrink?
I'm hoping that a direct short hasn't damaged my new controller unit or display. Is there any chance?
How could I test the wiring and hall sensors please?
Thoughts and advice welcome as always!

 

[Woosh]

How could I test the wiring and hall sensors please?

I use a breakout 9-pin extension cable for testing the Hall sensors.
I suggest you insulate the chafed wires then close the motor and refit the wheel.
If all works well then you have fixed the problem. If the same error re-occurs, you can test the Hall sensors at the controller level, where the 5-pin connector for the Halls is plugged into the controller.
The black wire is the ground, ask a friend to turn the motorwheel backward, that will engage the clutch and force the rotor to move, thus activating each Hall sensor in turn.
Switch on the electrics.
Put a Volt meter between the black wire and test each of the Hall sensor wires (green, blue, yellow).
You should see them flashing between 0V to about 4V. Any dead Hall sensor won't show normal behaviour.

 

[Nealh]

Read these simple to follow guides for testing,etc.

https://www.ebikes.ca/documents/HallSensorTestingFinal.pdf

https://www.ebikes.ca/documents/BlownMosfets.pdf

https://www.ebikes.ca/documents/HubMotorHallSensorReplacement.pdf

 

[vfr400]

That damage would prevent the halls from working, but it won't have done any harm because they're only 5V wires. A permanent repair doesn't look easy because the wires need to be tied back. You could try using high temperature silicone sealant (Instant Gasket). Put the silicone all over the wires, then use a piece of a plastic milk bottle with a weight on it to hold the wires down until the silicone sets. The milk bottle is made of polypropylene, which doesn't stick. If you want to have a go at retying the wires, you have to separate the rotor from the stator. Remove any circlips or nuts on the axle, then press the end of the axle hard to push it through. The magnets are really strong and act like a strong spring, which will keep pulling it back.

 

[orcecaveman]

That damage would prevent the halls from working, but it won't have done any harm because they're only 5V wires. A permanent repair doesn't look easy because the wires need to be tied back. You could try using high temperature silicone sealant (Instant Gasket). Put the silicone all over the wires, then use a piece of a plastic milk bottle with a weight on it to hold the wires down until the silicone sets. The milk bottle is made of polypropylene, which doesn't stick. If you want to have a go at retying the wires, you have to separate the rotor from the stator. Remove any circlips or nuts on the axle, then press the end of the axle hard to push it through. The magnets are really strong and act like a strong spring, which will keep pulling it back.

He he, I'm at this stage now. One of the terminals on the hall sensor came away (just like you said). I've dug out the old hall sensor and luckily I'd prepared for this happening and bought some replacements.
Here we go!!!!!
That's a brilliant tip about the milk bottle by the way!

 

[orcecaveman]

Its replaced. I've managed to push the new wires down and hot glued them. Hopefully that'll be ok as a temporary fix as I dont have any instant gasket until Monday

 

[orcecaveman]

In case anybody's wondering I used the chain wrench to hold the motor open against the magnetic force. I was carefull to not clamp it very tight preventing any damage.

 

[vfr400]

The hot-melt glue will melt when you use the motor because the windings become hot in use. That's why I said hight temperature silicone.

 

[orcecaveman]

The hot-melt glue will melt when you use the motor because the windings become hot in use. That's why I said hight temperature silicone.

I've done it as a temporary measure to test it. If it all works I'll be carefully removing it and replacing with instant gasket. It s ust that I dont have any and cant get any until Monday.
I've not got a milk bottle either!

 

[orcecaveman]

Sadly when all put together it's exactly the same. I think I've got to the point where it's like I'm chasing my tail.
I'm starting to think that a new hub is the way forward.
Any recommendations on which to get, decent makes etc? Would it make sense to upgrade to a 350W? Links to good / trusted suppliers would be appreciated please.
I have no idea of the make of the original hub.

36v 20" wheel.

 

[vfr400]

You need to test to find out why it won't work, otherwise you can end up replacing things and not solving the problem. Are the hall sensors switching? It could be that you popped a MOSFET in the controller when the hall didn't work.

 

[orcecaveman]

I've rested the mosfets, they're fine. It's still showing error 03 exactly as before, so I'm sure there is more damage to those hall sensor wires, probably inside the hub where I couldn't see. Everything except the hub moter is brand new

You need to test to find out why it won't work, otherwise you can end up replacing things and not solving the problem. Are the hall sensors switching? It could be that you popped a MOSFET in the controller when the hall didn't work.

I've rested the mosfets, they're fine. It's still showing error 03 exactly as before, so I'm sure there is more damage to those hall sensor wires, probably inside the hub where I couldn't see. Everything except the hub moter is brand new
.

 

[Woosh]

I suggest you unplug the motor cable and check for shorts between the Hall wires and the phase wires.

 

[orcecaveman]

I suggest you unplug the motor cable and check for shorts between the Hall wires and the phase wires.

I've just checked. There are no shorts between hall sensor and phase wires, but I do have continuity between all three phase wires.