Diagnosing a fault - motor or controller?

[pteron]

Hi all,

I recently posted regarding replacing the motor on my oxygen e-mate. I've done some further tests and I'm not convinced it is the gears that are at fault.

The motor will run and drive the wheel for about 5 minutes but then there is a graunching noise and the motor stops driving. No amount of throttle gives any response at all - no noise, nothing.

Any clues as to what might be wrong?

Thanks

 

[Deleted member 4366]

It's neither the controller nor the motor. It's a connection fault. Follow the wire from the motor until you get to it's connector under the bottom bracket. Check that there's no water or corrosion there, and check that it's fully home. The other possibility is damage to the wire where it exits the motor. Check it very carefully.

Whatever you do, don't use full throttle when it makes that graunching noise. You can blow the controller like that.

 

[pteron]

Thanks for the info. I've checked the connector and its pins are clean and shiny. The wire exiting the motor has a spring wrapper that appears undamaged.

Can you explain why you say it is a connection fault?

Thanks

 

[Deleted member 4366]

The motor is three-phase. When one phase gets interrupted or mis-timed, you get a fierce juddering that feels like mechanical mayhem. If your Oxygen is old, there may be additional connectors in the compartment under the battery. Have a look in there. Follow the wires all the way from the motor into the controller to check the three phase wires and five hall wires.

You can also get the same symptoms when you have a dodgy hall sensor in the motor or a dodgy FET in the controller. Check all the simple things first.

 

[pteron]

Thanks again for the help. That's useful info.

I wouldn't describe the graunch sound as a judder and it lasts maybe half a second and then there's silence. The sound is more like someone grinding the gears on a car because they've mistimed the clutch.

The wires disappear into the bottom of the controller through what looks like a silicon sealant.

I will investigate more tonight, but any further insights you have would be very welcome.

 

[Deleted member 4366]

What you describe exactly matches what happens when you get a faulty connection or short on a phase or hall wire, or when your controller loses sync with the motor for whatever reason. With these type of connectors, it's very difficult to test because you can't get meter probes or an ebike tester to the connection points.

There's no need to look inside the controller because it's sealed. The older Oxygens had connectors just outside the controller, but it seems that yours is a later one from what you describe.

Did the problem start after any particular event, which might give some clue to the cause?

 

[pteron]

I asked the former owner - "It happened going up hill steep peddling hard. Graunchy noises. Lost all power."

 

[awol]

I got that juddering/noise once so stopped using power straight away for the rest of the journey. When I checked connections one of my phase connections was loose at the controller. Reconnected and all was fine again.

 

[Deleted member 4366]

I asked the former owner - "It happened going up hill steep peddling hard. Graunchy noises. Lost all power."

Are you sure that the multi-pin connector is fully home/ There's a line on the inner one where the edge of the outer one has to reach.

 

[pteron]

Yes I believe so - I line the arrows up and pushed it home firmly.

The thing that puzzles me is that once it has stopped (after about 5 mins) I can't get it working again, but generally the next day it will start again. Unfortunately so far, there has always been some fiddling done, so I don't know if it is a pure timeout or if the subsequent fiddling reconnects something.

If it is a damaged connection it could be in either end of the wire. The connector from the controller has been replaced I'm told.

 

[Deleted member 4366]

Yes I believe so - I line the arrows up and pushed it home firmly.

You have to check that the edge reaches the line!

 

[pteron]

I'll do that tonight - reach or bury the line?

 

[Deleted member 4366]

The edge should be just about on the line.

 

[pteron]

Tnx. Will check tonight.

 

[pteron]

The connector is pushed home so it isn't that but I think you are right about the connection fault - I can occasionally get it to make connection by manipulating it and the motor will run. I can't find a position to clamp it that lasts for more than a few mins though.

Without a spare bike to check it against, I don't know which end is faulty. I thought at first it was the bit connected to the motor but I'm not 100% sure. Are there re-wiring kits available?

 

[Deleted member 4366]

It's almost impossible to fault-find these. One wire is connected to the motor and the other the controller. You can't get at the connections in the controller because it's full of jelly. Neither can you get at the connectors because they're moulded. - great for waterproofing, rubbish for fault-finding.

Unless you can find it by twizzling the wires, you have to exchange the controller and motor to find out which is faulty.

 

[pteron]

I did a bit more disassembley yesterday and took the side off the moulding that houses the controller. I discovered that the wires all have connectors on them before entering the controller. I'll run the DMM over the wires to the motor connector so I can at least see if that section is broken.

Thanks for your help, it has been invaluable.

 

[Deleted member 4366]

I thought you said in post #12 that you didn't have those connectors. That's easy then. Pull apart the three thicker phase wire connections, crimp the barrels a bit tighter and re-connect.

 

[pteron]

Yes, apologies - I was under the impression that the plastic housing was the controller and that the white gunk was as far as I could go - didn't see the screws at the time.

I'll try that tonight.

 

[pteron]

I've checked all of the connectors and re-seated them but no difference.

I also checked the connections between the controller connectors and the connector halfway to the motor and they are all fine.

It looks like the break is between the external connector and the motor and adjusting the angle the cable goes into the motor does make it work. I've taped it into position to see if it will run for a while, but I'm going to need to rewire this section - any idea if this is a standard part or do I need to ask oxygen for it?

Next is to open up the motor and check continuity on each wire.