stuttering motor problem

[giguana]

shuddering motor problem

The motor on my bike is making a strange stuttering sound that happens 8 times every time the wheel goes round once, it makes the bike vibrate with little thuds that go faster depending what speed I'm going...

At first it was fairly occasional but now it happening quite a lot, there is also some kind of a decrease in power. it's a crystalite 406, Any ideas what it might be?

Thanks!

faulty electric bike motor - Putfile.com

EDIT-in the end of this was due to moisture in the motor was okay again with some drying time, I thought the xlyte inside would be well protected with seals but you really have to do it yourself with silicon sealant or Vaseline.

 

[Miles]

It's possible that you have a broken connection to one of the hall sensors in the motor. There will be 3 thick wires and 5 thin wires going into the motor - the hall sensor wires are the thin ones - they are quite vulnerable...

 

[giguana]

the thing is, it also happens when the motor is turned off, just a rolling of the wheel along the ground at walking pace, it's as if there is a magnet that stays stuck in on mode that makes the wheel jolt abit eight times for every turn rather than spinning smoothly.? it is like a a series of dull thuds coming from inside the motor

 

[flecc]

If yours is a geared hub motor, it may be the freewheel has seized. Normally the small jolts from the magnets are only felt when the wheel is turned backwards, the freewheel allowing the wheel to turn without the motor when going forwards. If the internal freewheel has seized, you'd feel the magnet tugs in both directions.

The main difference a seized freewheel would make is that pedalling the bike with power off would be much more difficult.

If it's not a geared hub but direct drive, or if the jolts are severe to the point that the wheel seems as if it's going to lock up, there's something more serious adrift internally.
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[giguana]

it is a gearless motor with three wires going to the power plug, here is a sound recording of the faulty noise, it's pretty loud, after 25 seconds the power stops responding altogether and that's me clicking on the thumb throttle. so I had to turn the wheel around by hand to get it started again-you can hear the motor makes the same sound when it's just going round manually. I accelerated a bit too hard in the first bit to demonstrate the sound-it sounds bad!!


faulty electric bike motor - Putfile.com

 

[flecc]

That does sound bad. Normally I'd have suspected one of the connections open circuit somewhere between the motor and controller or a controller fault, but since you've observed there's something wrong even with power off, it seems it's a mechanical fault having an electrical effect as well.

I don't know the Crystalite motor so I could only guess at the possibilities which wouldn't be much help. Maybe a phone call to Team Hybrid would be an idea, since they know these motors well and use them on their display team bikes.
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[giguana]

it's definitely an electrical thing-on further investigation it makes no noises when the controller is off so all electricity to the motor is off, it just makes noise when the motor is powered up on standby or with the throttle.

I think it must be one of the magnets which is staying switched on-I think I have to open up the motor and try to fiddle with the wires to see if it is possible to make the contacts come on and off...also maybe like that I can measure all the wires coming from the controller with a multimeter.

 

[flecc]

In that case an open circuit lead is very likely, the connection failed at a motor coil take-off point, at an inline connector in the lead, or at the controller end.

The alternative is a controller failure, and I have heard of these with the Crystalite motors.
.

 

[giguana]

I have no idea how to open the motor, on one side there is a freewheel and I guess i have to take off the freewheel from the hub cap to be able to uncover the hub cap? on the other side there is a cable squeezed next to the axle which makes taking the cap off really hard.

I get you mean about not starting, it's when the wheel is stopped opposite the faulty magnet somehow?

 

[flecc]

I'm not familiar with it so can't advise there. It's simple with the eZee motors, one end cap with both freewheel and cables on that side, so no choice to make.

It seems the more difficult cable side is likely to be the one, since opening the other side will mean withdrawing the armature to see the connections, meaning the cables would have to be pulled through anyway.

Definitely a case of proceed with great care, and a word with Team Hybrid first could still be a wiser starting point. I've often found that a company familiar with a product instantly recognises such fault conditions and is happy to give free advice. Using this strategy has paid off for me many times in various product fields, saving much time and effort.
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[Miles]

Technical info (including how to open the motor) and pictures, here: Crystalyte - Europe

Miles

 

[Jeremy]

It might be an idea to email Justin at ebikes.ca, he knows far more about these motors and controllers than anyone else I can think of.

My best guess, from the limited information, is that one of the FET pairs on one phase has blown - not a rare event with the lower rated Crystalyte controllers. It may be that just one FET has blown. When these FETs blow, they apparently nearly always take out the gate drivers and drive current limiting resistors too, so these are worth checking. A look on the Endless Sphere forum will give you loads of useful information on repairing the controller.

The good news is that these controllers are very easy to repair, and uprated FETs are readily available to make them virtually immune from failure, even with severe abuse!

The best replacement FETs seem to be IRFB4110's, these will happily tolerate working at voltages of up to 72V or more, with very high currents (> 40A). These fit straight into the 12 FET Crystalyte controllers (the 48V 35A ones).

Hope this helps,

Jeremy

 

[giguana]

Thank you! That is really very helpful, team hybrid is really good, I think if ebike Justin helped design the cycle analyst I'll see if he has come across this before as a first port of call.

because it's easier-I think I can safely check inside the controller and smell if anything is burnt.

thank you so much Flecc, Miles and Jeremy.

 

[giguana]

Justin says it is usually something to do with water in the motor, it sounds very much like a hall sensor thing to him. often it dries out again. It shows the importance of sealing properly!

 

[flecc]

If you have a dehumidifier, or hire one, putting the bike or motor wheel into a closed small room with the dehumidifier flat out for a few hours is a very effective way of drying out damp e-bikes, motors, controllers etc. A bit of warmth is needed in the room as well to get the maximum dry air production.
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[giguana]

have managed to dangle the wheel above a radiator with lots of the screws undone for extra ventilation and I have tried it again about five hours later and it turns well again!

so I will keep it drying for a couple of days and then I will try and seal it.

does silicone stick well to aluminium? I have some in stock and I am familiar with laying it on so seems like a good option although there might be a better one.

fantastic news anyway.

 

[flecc]

The Panasonic motor unit's cast aluminium cases are sealed with silicone sealant, and I've resealed using the usual DIY stuff, so yes, ideal, as it doesn't permanently stick.

Great that it's going again without problems.
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[tgame]

have managed to dangle the wheel above a radiator with lots of the screws undone for extra ventilation and I have tried it again about five hours later and it turns well again!

so I will keep it drying for a couple of days and then I will try and seal it.

does silicone stick well to aluminium? I have some in stock and I am familiar with laying it on so seems like a good option although there might be a better one.

fantastic news anyway.

Good news that it's going again, Giguana. Congratulations.

 

[Jeremy]

Very good news that it turned out tobe something so relatively easy to sort out. My best guess is that using the type of silicone sealant that cures to generate alcohol as a by-product, rather than the type that cures by generating acetic acid, might be best. I once caused quite a bit of corrosion in a sealed assembly by using ordinary household silicone sealant that gave off acetic acid as it cured.

As far as I know, most of the silicone sealants sold for indoor use in bathrooms and the like tend to be of the alcohol cure type. The acetic acid cure ones are easy to distinguish as they give off a very distinct vinegar smell as they cure. The alcohol cure types have a faint alcohol like odour.

Another thing that might well be worth while is coating the vulnerable internal electrics with a waterproofing varnish. This might make sealing the casing less critical. RS Components, Farnell etc sell aerosol tins of conformal coating, intended for sealing circuit boards. This might work on the Hall sensors and associated wiring inside the motor.

Jeremy

 

[giguana]

really sound advice there Jeremy, just this minute, I have finished sealing it with an acetic acid silicone, but that's what I had already at home and I just read your post. I was wondering what that vinegar smell was. I was guessing it was hydrochloric!

I wanted to put something inside the motor but then I would have to open everything up, I was thinking along the lines of WD40 of desiccant bags that you get in shoes.

waterproofing varnish sounds like a very good call, if only it was possible to spray through the screw holes without taking off the whole thing, disassembly of the hubcaps is pretty hard you need a kind of giant corkscrew for the axle

the most tricky thing about applying silicone is having to unscrew the frewheel-I'm figuring I have to do that as well although the most important is probably around the electric cable.

I will port all this information over to the crystalite guide that I did. justin said that 80% of the problems to do with hall sensors are because of moisture and he has seen motors completely encrusted with gunge and corrosion.