What could be wrong with my bike?

patrickza

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Jul 6, 2008
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491
After 12000 trouble free miles I seem to have my first bike gremlin :(

This morning everything seemed normal, but on one pull off dead stop the bike seemed to start much rougher. This is unusual for me on a flat road, it might happen much more slightly on a steep hill. At speed it seemed smooth again, but my max amperage dropped from +-50A to +- 45A, with a corresponding drop in power. The rough starts seemed to stay with me.

I'm running a cromotor and 18fet lyen, any ideas on what to start checking or should I dismantle the bike and get my controller to Lyen to give it a once over.

Here's the full specs on my bike: https://endless-sphere.com/forums/viewtopic.php?f=3&t=45514

Thanks
 
Rough motor operation usually means a hall or phase connection problem, anywhere between the controller and the motor. Can be wires broken inside the insulation, contacts backed out or bent, etc.

Sometimes it's an electronics problem; bad hall sensor, blown FETs, etc.
 
Ah okay, so likely not the controller then. I'm not an electrical guru by a long shot, is there anyway to test the hall sensors?
 
Sure, there's good methods for testing those and other things over at http://ebikes.ca in the Learn / Troubleshooting tab.

But first, as I said, check all your connections and wires--they are MUCH more likely to be the problem.
 
Another piece of info if it helps, on my ride to work I used about 20% more AH than normal. Visual inspection of the cables seemed okay at a glance, will look in more detail when I'm home.
 
Might look first at the battery to controller contacts. You might be having part of your problem there.

Then look for obvious stuff, clear problems with the plugs to the motor, then bother with checking halls.

It might just be the controller after all. A motor/controller/ throttle tester is what you need to make looking at all that easy.
 
patrickza said:
Another piece of info if it helps, on my ride to work I used about 20% more AH than normal. Visual inspection of the cables seemed okay at a glance, will look in more detail when I'm home.
False alarm on the battery usage, just got home with normal AH used.

The pulloffs from standstill are very very rough, I'm now thinking it's hall sensor related. At speed things feel normal apart from the 5 or so amps max current that's missing.

I might have a tester in storage somewhere, will go try find it.
 
A visual inspection of cables won't likely show you much, unless it's a backed out or corroded contact or obvious disconnection or break or wire damage. Most of the time, this is exactly what happens.

For the rest, you'd have to continuity test the wires and connections, preferably with the connnectors still plugged into each other so you're testing the actual connection being made there, to know that they're ok. For the latter, you'd have to get to teh wires inside the cable sheath, and poke your probes into the conductors inside the wire insulation, one meter lead at the motor end, and one meter lead at the controller end.
 
Sounds like a bad hall possibly, it will start rough in some positions but not all, and sometimes act funny when it cannot sense the stator position during use.
 
I agree it sounds like one of the hall signals is missing.
I would unplug the hall sensor cable between the motor and controller and inspect carefully. Sometimes just unplugging and reconnecting a connector will fix a problem.

It is possible the actual hall sensor went bad, but this is rare unless grossly overheated.
It is also possible the controller is bad, but also unlikely.
 
Okay so I checked the hall cables by unplugging them one at a time. Unplugging any of the 3 colours maks the bike barely go, so I think all the halls are fine. I also had the bike upside down and the wheel was able to move extremely slowly. Next I unplugged all the phase wires. They all had some dirt in them which I cleaned out with a Q tip and some alcohol. No change there.

Pulling off slowly seems smooth, if I try pull off fast it makes huge vibrations and noise.

What could I check next?

I need to change the rear tyre anyway, so I'll remove the covers to see if there's anything obvious, anything in particular I should look for when I do that?
 
I'm having this problem at the moment too. I had the same issue a while back too - back then it was a water ingress issue and the hall wires were shorting against each other.

This time though it's intermittent and was not easily identified - and as someone said in a previous post is down to a wire that has broken down within its insulation. If I bend the hall wire at just the right point, the problem goes away. I'll be fitting a new hall wire later today.

What I found was that if I lifted the back wheel and used the throttle, initially the wheel would rotate backwards for a fraction of a second. If I was sitting on the bike, causing a far greater load, the bike would almost kangaroo, kind of like if I was trying to pull away from a standstill in 5th gear in a diesel car!

Jon
 
Here's a video showing everything is perfect without load:
https://www.youtube.com/watch?v=z9vvhofSaog

Edit: and here's a video from ypedal where his motor behaves similarly to mine. Ypedal are you here? Any idea what went wrong there?
 
I have a Greyborg and Cromotor V3 just like you and am going through an identical issue.

I’m fairly certain, up to 95% sure, it’s the hall sensors inside your Cromotor or the wiring leading up to them. There’s certainly an off chance that it’s an internal issue inside your Lyen controller or something different altogether but that would be a bet not in your favor.

You likely have a secondary set hall cables coming from your Cromotor. Have you tried switching over to them and seeing if the issue resolves itself? The colors will be different, a combination of purple, gray, orange, black, etc. If you post a photo here I can help you determine which one is which.

You can test your hall sensors. However, you can’t just stick 5V and ground on the red and black cables from your power supply and poke around with the multimeter on the signal wires. You’ll need a pull-up resistor to get proper readings. So the best way is to intercept the multimeter leads within the JST connector into your controller. I’ve had success taking bits of un-melted rosin core solder and jamming them deep into the JST pins and then hooking alligator clips onto it.

Good luck!
 
PS - The correct replacement sensors for the Cromotor are Honeywell SS441A-S. You can use the SS441A’s but you’ll have longer “legs” off the sensors to deal with. Make sure they’re unipolar and not bipolar. I made this mistake and am having to replace them for the second time right now.
 
My cromotor is one of the originals, version 1. I'm going to try this to test the hall sensors soon: http://www.ebikes.ca/documents/HallSensorTestingFinal.pdf

Let me know if your cable swap solves the issue.

I see the link to ypedal didn't get posted earlier, my bike sounds very similar to this: https://m.youtube.com/watch?v=xBrJ_aXWRCk
 
Back from holiday and I did more testing. This time I used the multi-meter on the controller side of the hall connector.

When I had the connector on the black and blue it would switch between 0.02v and 4.97v as I turned the wheel. The exact same values were there for the black and green. The black and yellow combination went from 0.02v to 4.89v.

I have no idea if that's a significant enough difference to affect my bike like that.

Any thoughts or ideas on what to test next?
 
patrickza said:
When I had the connector on the black and blue it would switch between 0.02v and 4.97v as I turned the wheel. The exact same values were there for the black and green. The black and yellow combination went from 0.02v to 4.89v.

That sounds pretty normal. I don't think that much difference is a problem. That pretty much tells you the motor is OK.

So the controller is about the only thing left. If it was mine, I'd take apart the controller and look very carefully at all the solder joints on the board, especially around where the hall signals come in. If you're lucky, there will be something visible, like a bad joint or bridged traces, water damage, etc. There could also be damage to the hall cable somewhere between where you measured and the controller.
 
Okay so I got hold of a 9fet lyen controller and plugged that into the bike. Obviously it was lower on power, but symptoms seem similar, which kind of rules out the controller. Now I'm back at square one, no idea what to look for next.

The key symptoms are very rough start until I get moving, and then 15% lower amps at wide open throttle. I'm totally stumped!

Could it be a damaged phase wire? Or possibly a hall sensor which fails under high amps?

I didn't think it was the battery as I don't have any more voltage drop than I would expect, does that rule it out?
 
How does the motor spin with no load connected? Just last month someone had a cro motor with the magnets coming unglued. With 12k miles this may have happened. It will sounds rough but still operate for the most part.
 
With no load I have no problem, here's a video: https://www.youtube.com/watch?v=z9vvhofSaog

I've had the side covers off the motor, but without something to pull the stator out I couldn't really check the magnets.

Here's a couple of pictures:
https://imgur.com/a/ZMfHoEB
and
https://imgur.com/a/Xiprq0L

Edit, just links now, couldn't figure out how to get them inline
 
patrickza said:
Could it be a damaged phase wire? Or possibly a hall sensor which fails under high amps?

I didn't think it was the battery as I don't have any more voltage drop than I would expect, does that rule it out?

I don't think the hall sensors would fail only at higher motor currents. If the battery voltage is normal under load, that should be OK. Normally if the pack voltage sags too much, it will totally cut off the power.

To check the phase wires, unplug them from the controller and measure the resistance between each wire an the other two. On the meter, it should measure less than one ohm. If one of them is broken somewhere, it would look like an open circuit.
It's pretty rare for a phase wire to break.

Another way to check the phase wires is to unplug them and short any two and spin the motor by hand and feel the resistance. Repeat with all possible combinations of wires. You should feel a strong resistance to spinning the motor when the phase wires are shorted.
 
Time to re-open this thread. I'd stopped commuting on my bike for a while, but now I'm back on it again. Problems are still the same, though they completely disappear once the bike is just moving even at walking speed. I'll have to get hold of a better multimeter to test the resistance between the cables better.
 
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