Strange issue with motor

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ulti   1 mW

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Joined: Dec 17 2013 9:20am

Strange issue with motor

Post by ulti » Mar 18 2021 1:00pm

Hi,

Few days ago during ride I heard spark sound and power loss from motor when pushing throttle. After inspection, I found damaged isolation on phase wires from motor. Since isolation was damaged on 2 wires near axle, I was confident about reason for this.

I've replace phase wires from controller to motor, but noting changed. Still same issue.

Any idea where can be problem? Anyone had a similar problem?

Motor: Crystalyte HT3525 sensorless
Contoller: Lyen 12 FET 4110 MOSFET MK2 sensorless

Thanks
Cube AIM 2013 / HT3525 /20S LiPo

goatman   100 MW

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Location: Surrey, B.C.

Re: Strange issue with motor

Post by goatman » Mar 19 2021 12:49am

my hs3540 kept eating motor cables where the cable passes through the axle and bearing

hand filed all the sharp edges on the axle especially where the bearing meets the axle, its a really tight bend there internally and zip tied the motor cable to the axle on the outside so the disc brake bolts dont nick the cable

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amberwolf   100 GW

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Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
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Re: Strange issue with motor

Post by amberwolf » Mar 19 2021 2:02am

Unless you're *certain* the spark sound comes from the motor, you should check your battery and phase connections on the controller. A poor connection would work ok at low currents, but could arc on higher currents from higher throttle demands.


You could have windings on the stator itself that have damaged insulation, and the spark could be it shorting to the laminations, or to other windings thru the laminations. Or inside the axle itself, depending on how much of the wire you have replaced.

It can even be a phase wire connection to the windings, sticking out enough to eventually rub off the insulation and short to the cover as it spins. The pics below are from an MXUS3K 450x, but the problem can happen in any motor:
Image
Image


The 35xx series of crystalytes are not very well made motors, in my experiences with an HSR3548. This is one example of a severe mechanical problem you can encounter, because of the axle design, for instance:
Image
What you are seeing is the axle where the bearing sits, has become "compressed" or worn (not sure which). If it's compressed, it might be the electroplating they put on the axle deforming vs the actual axle steel underneath that (there is clearly a layer of copper colored metal, and a layer of shinier metal on top of that, my guess is nickel plating to reduce corrosion on the axle steel?). Why it deformed is likely the out-of-roundness of the side covers, which are so out of round that they cause unscrewing and ejection of the cover screws over days to weeks (with loctite!), even having tried at least a dozen different screws (different metals, hardnesses, shapes, heads, lengths, thread shapes/depths, etc). Sometimes they just snap the heads off instead of unscrewing, making the problem worse for the remaining usable screwholes.

This axle problem results in wheel wobble, whcih makes the problem itself worse as it wears at the axle more, and it can make the cover problem worse, and eventually even make the covers start rubbing on the wires and windings....
Image
Image


The covers are also not cast very well, with defects and voids. Might be hard to see in this pic
Image
but you can see the two pretty large voids as dark spots near the edges, across from each other, in this one of the other cover
Image

ulti   1 mW

1 mW
Posts: 11
Joined: Dec 17 2013 9:20am

Re: Strange issue with motor

Post by ulti » Mar 21 2021 2:55pm

Lowering "Max startup current" in ANT BMS configuration solved issue :roll:

At least now I have upgraded phase wires :)
Cube AIM 2013 / HT3525 /20S LiPo

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