Expensive noise

[flecc]

Testing the Q bike on a 1 in 3.3 hill section on motor only until near stall point, suddenly a huge grinding crash from the rear motor wheel and then it locked, at the very least the motor totally wrecked one might think.

Bounced the bike on the ground a couple of times until the drive returned and set off again. A bit further on it happened again, same cure, then from the top of the hill, a gentle minimum throttle ride home.

So did I strip the hub to see the damage? No, I just checked the Hall sensor lead and unplugged it at it's five pin connector under the bottom bracket, used contact cleaner on it, replugged it and re-insulated it.

So what was the horrendous noise? These very powerful hub motors have such strong magnetic forces that they are completely dependent on the pole magnetic fields keeping in perfect balance. The loss of one sensor connection threw the fast spinning rotor with it's heavy magnets so far out of balance that it struck the stationary stator with considerable force, the noise of the impact amplified by the alloy hub shell.

So if this happens to your very expensive e-bike, turn white by all means, but don't chuck yourself off the nearest bridge, just check and re-plug the connections of the five sensor wires and three power wires from the hub.

Some while ago there was a discussion about adding a plug in connector on the Torq, and at the time I advised against it, saying that soldered connections were better for just this reason. If my Q bike connector plays up again, I'll be taking my own advice and solder in place of the connector. No matter how good a plug, eventually they can lose a connection and perhaps strand you if you're not sure what's happened.
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[coops]

yikes! Still, good to know that .

 

[Ian]

Thanks for the warning on that potentially frightening situation Flecc. My Torq, and presumably all of those made since has a multi way plug & socket part way down the RH fork leg to facilitate wheel removal, obviously this is a potential cause of that problem, particularly for bikes used regularly in wet weather.

 

[flecc]

I've never seen one of those new Torq connectors Ian, but I understand they took some care over quite a while before specifying the one used, obviously knowing of the potential for trouble, so hopefully it will have higher than usual reliability.

The five way one that's on the Quando's Hall sensor leads is the same type as that on the throttle, a standard flat electronic connector not originally designed for this sort of critical application, and that's accompanied by three automotive pressed metal in line connectors for the phase power leads.

The Q bike Hall sensor connector has limited use for me since none of the wheel nut, washers, spindle support sleeve and multi-sprocket freewheel will pass over it anyway, so I have soldered connections in the lead on the wheel side of it anyway.

Therefore it's only useful for a tyre/tube job, which don't need full disconnection!
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[Ian]

The five way one that's on the Quando's Hall sensor leads is the same type as that on the throttle, a standard flat electronic connector not originally designed for this sort of critical application, and that's accompanied by three automotive pressed metal in line connectors for the phase power leads.
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I'm fairly sure from memory that is what is on the fork leg of my Torq, certainly the car type bullet connectors are in the phase wires, incorrectly colour coded which caused some head scratching the one and only time they were disturbed. I didn't have the benefit of your knowledge then.

One concern I do have over the motor wiring is eventual breakage from the constant flexing between the frame and forks, I guess if this does happen the thin senor wires will go first giving similar symptoms to those experienced by you today.

 

[flecc]

Oh well, hopefully won't give trouble anyway Ian, and at least very easy to get at alongside the fork leg. My Torq/T bike still has directly soldered Hall sensor wires and the three bullet connectors, both Q and T having wrong colour codes.

Very common in all Chinese production, not just bikes, and maybe just the ex-rural workforce thinking the colours are there for the pretty effect.

Fortunately they no longer do that on mains connectors, they did briefly at one time in the earlier days!
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[aaannndddyyy]

Hi good timing Flecc, a friend of mine came over last night on his Crystalyte 504 kit bike with the same symptoms that you described on your q bike, saying his motor had broken asking if I had any suggestions, sounded rely ruff with little power and no torque I showed him your post, he rang this morning very happy as a good clean of his connections has fixed the problem.

 

[flecc]

That's great news aaannndddyyy, it's always gratifying to know that a posting subject has a value for someone, and even better when the timing is dead on.
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