High-Pitched Motor Noise

Discussion in 'Hyundai Kona Electric' started by SeanH, Apr 29, 2019.

  1. victor_2019

    victor_2019 Active Member

    What lower price point?

    In Canada the bolt is 2000$ more expensive for same features, and has a horrible plastic interior and less range.

    The leaf is also 2000$ more expensive and has much lower range at 360km plus no thermal regulation on the battery meaning charge throttling and battery degradation of 4% per year (that's what they had in the previous model, no reason to believe this new one will be better when they cram a higher density battery in the same physical space with no cooling)

    Kona preferred at 45k vs bolt at around 47k when you include the first safety package to get the radar cruise, automatic brake etc. And 47k for the leaf sv+.
    robxb and Kamloops_KoNa like this.
  2. "I really really hope Hyundai monitors these or other forums."

    Hahahahaha hahahahaha hahahahaha hahahahaha hahahahaha hahahahaha! You slay me!
  3. I'm not in any way doubting that people are hearing and are annoyed by a noise but is the spotty nature of the reporting as simple as younger ears vs. older ears?
    Brennan Raposo and CJC like this.
  4. eastpole

    eastpole Member

    Most people wouldn't have a theoretical understanding of this question (e.g. why do transformers sometimes buzz?) but you might have had a similar experience. I've certainly heard one pot light, out of a whole ceiling installation, that seems to hum or buzz audibly while the others don't.

    If this is the cause of the problem, I'm surprised.

  5. Everybody knows why a transformer hums and that's because it does't know the words :D
  6. SeanH

    SeanH Member

    This has definitely occurred to me, which is partly why I made the recording. But it still may be that some people can hear the sound in the recording but not on their car due to other ambient noises.
  7. Kona Bear

    Kona Bear New Member

    i know i'm late to the party but i had the same issue as well as another almost growling type of sound. neither sound started until right before i hit 2,000 miles which was about 2 months. i personally didn't think much of it and it never effected drive but it was annoying me so i bought it to the dealer. well they had it for a little over a month, the engineers looked at it, video was taken etc. i had both the Motor replaced as well as the Gear Box replaced. the weird growling sound is now gone (which was the one that was a little more concerning) but that lovely high pitched sound is still there, i only hear it with the windows open and once i hit about 25mph it's gone. considering i just got my car back i want to drive it for a little before i decide to bring it back. i know i have read a lot of you say it's not the breaks or regen but i can tell you it's also not the Motor or Gear Box, since i have brand new ones in my car. to me it always sounded like a rubbing somewhere, now that it's warmer something expanded just enough to annoy all of us. i hope this helps and hopefully we can figure this all out.
  8. First post mentioning motor /gearbox replacement, glad it worked out well for you. Did they supply you with a loaner while being serviced? One month for replacement seems pretty good time wise.
  9. Kona Bear

    Kona Bear New Member

    i thought that would help some others out knowing that the sounds can't possibly be coming from the Gear Box or Motor since i'm still having that same lovely noise myself after them being replaced. yes i did get a loaner which was the worst, i ended up getting the lowest end Elantra (my phone screen was larger), that car is one of the smallest and most uncomfortable to drive and i'm not a tall person. after a couple of weeks of that and me bugging them all the time i got a new loaner and i mean new (had only 14miles when i drove it off the lot). they gave me a Tucson. i understand that it all had to take some time since this is a first year model and first time the Tech was working on this type of car. but it did at times take a week to decide lets replace the gear box, then about 4 days to arrive etc. i'm hoping that with this happening to me it will help speed up the process for future issues to be diagnosed at a much more reasonable rate. i do absolutely love my car, went with the Ultimate Edition and since it's been so long without i plan to drive it for a while with this squeak to see if anything changes, gets worse or magically goes away before i decide to bring it back to the dealer to see if they have any other ideas now knowing it may take another month to figure it out.
    robxb and electriceddy like this.
  10. Brennan Raposo

    Brennan Raposo Well-Known Member

    Wow! How did you manage that?! Every time I walk into the dealership they treat me like I'm an annoyance. I've been bringing my car in for this noise 3 times over the last 3 months and nothing ever gets done about it. They just keep telling me "until it's a recall, there's nothing we can do about it"
  11. Kona Bear

    Kona Bear New Member

    i'm in CT and keep in mind i still have this sound that everyone else does, but there was another weird sound that i guess had to do with the motor because once they replaced that part it was fixed. at first they thought it was just a weird air movement noise but once they really listened to it they realized it wasn't and called the local Hyundai engineer to come down to take a look. he came next day and was also unsure what the issue was to the point that i was told the video/photos went to a room full of engineers somewhere to think about what might be wrong and how to fix this issue. that when they came up with the Gear Box replacement first. then after they installed and test drove the scratched their heads again surprised the sound was still there. so i hate to say it but maybe because i'm a Girl it helped not sure but my dealer has been really nice and never had an issue looking into it with me. which is why i will definitely go back if this other sound doesn't go away but i'll make sure to schedule it with a nicer loaner upfront.
    my suggestion is to try a different dealership, you are not required to go to the dealer where you bought your car to get service
  12. victor_2019

    victor_2019 Active Member

    Why do you think this can't come from the motor?

    The motor is exactly where it comes from. Harmonics from the inverter switching are causing vibrations in the motor windings/frame and this is what you are hearing.

    It's perfectly normal unfortunately.

    And the fact that other cars like teslas don't do it is not really relevant because they don't use the same inverter technology. The topology and number of levels in the inverter, the switching frequency, the switching patterns and control methods all make a difference in the harmonics and noise you will hear.

    And i can tell you i can hear a similar noise in my honda clarity. The difference is that it's not as loud, but there's definitely a high pitched noise when accelerating or in regen and no noise when there's no load on the motor, just like the Kona.
    Kitsilano likes this.
  13. SeanH

    SeanH Member

    The funny part is they are probably using spread-spectrum PWM in order to spread the electronic noise out to pass EMC/EMI... but if they had just used a fixed frequency above hearing range, it would've been better for humans.
  14. Kona Bear

    Kona Bear New Member

    it still doesn't make sense for it to be the motor since i have a new one. in theory it would take another 1,500 miles give or take for that sound to come back if it was the motor and it should have stopped once they made the switch, then after x amount of miles it would come back. since the sound never stopped is why i think it has to do with something else.
  15. I do tend to agree that unfortunately it's probably normal. I'm pretty sure my Kona does make this noise when hammered but it's very subtle to my ears and doesn't bother me. We know from the recordings that it's mostly broad spectrum rather than one specific frequency. I've attached a presentation below from Siemens on this subject, specifically page 23, noting they indicate all HV components are potential sources. The link is from another engineering consultant.

    Attached Files:

    SkookumPete and Kitsilano like this.
  16. It does seem to indicate a spike in PWM electromagnetic noise @ 10kHz and 20kHz in their example diagram on page 3.
  17. victor_2019

    victor_2019 Active Member

    you assume this is a problem with the motor when in fact it's perfectly normal and all motors will do it.

    current harmonics cause torque harmonics which cause vibrations in the motor frame.

    vibrations cause sound.

    if the current harmonics are in the audible range then you will hear the sound.

    this is all perfectly normal unfortunately. And there's no such 1500 mile limit when this starts, it's right from the beginning. I dont even have 1500 miles on my car yet, and when someone tries a new car on the lot and hears this noise, that car won't have 1500 miles on it either.

    This is a fundamental consequence of the way the motor is controlled/the way current is generated by the inverter.

    I guess I've been working around VFDs for about 15 years now and I'm used to all sorts of weird noises coming out of VFD controlled motors, the noise out of the kona is nothing special really.
    Jared Potter and SkookumPete like this.
  18. BlueSal

    BlueSal Member

    I hope someone complains to NHTSA, or Hyundai USA discovers a fix, so this problem can finally be identified and resolved.

    This is my experience, driving home after purchase, I noticed a ton of road noise from the tires. Otherwise, the car was silent.
    On the drive to the tire store to buy better tires, I rolled down the windows and carefully noticed the existing noise, so I could evaluate the new tires. There was no squeal/hissing sound.

    Once the new tires were on, this sound appeared (@500 miles). It made driving with the windows down impossible.
    Now at 2,000 miles, the volume of the squealing/hissing noise has gone down by probably half.
    Anyone else find that the volume decreases with time and mileage?
    Is this a problem solving itself (high power cables?), or am I on the cusp of a massive failure of some component?
    Do inverters fail? I assume if they do, the symptoms would be lack of charging or a warning light?
  19. victor_2019

    victor_2019 Active Member

    you realize that people come here and complain about all sorts of noises that are actually unrelated to eachother?

    some people complain about brake squealing noises that are fixed with brake hardware replacements, some talk about clunks which are related to suspension/control arms that need to be replaced, some talk of noise from gearbox which was fixed by changing the gearbox etc.

    these are all mechanical problems on those particular cars that were fixed by mechanics and have nothing to do with the harmonics noise some people hear.

    regarding the constant hiss that can be heard when the car is accelerating/regenerating, which goes away when there is no load on the motor/inverter, this is only noise caused by current harmonics. (I'm not talking about any other noise. I can't tell what noise you in particular are hearing, it could besomething completely different.

    why would someone complain to the NHTSA? this is not a safety issue.

    Yes, inverters can and do fail sometimes. And I suppose some failures could cause an increase in harmonics which would result in more audible noise.

    But just the fact that you hear the noise caused by harmonics is not a sign that something has failed or is about to fail. And the noise shouldn't go down really.

    Noise is caused by harmonics and harmonics are caused by the difference between the current shape and a pure sinusoidal. The closer the current is to a pure sinusoidal, the lower the harmonics are, and the lower the noise will be.

    an inverter failure will make the current waveform uglier, not nicer. It will not result in less harmonics or less noise, quite the contrary.

    and while the inverter hasn't failed, I don't see how it could change noise because it's about to fail.

    this is a piece of electronics, it either works properly or something is wrong. it's not a mechanical gear that can change noise as it wears down.

    I suppose some failures could be intermittent and be related to factors such as heat or humidity, but again that wouldn't make the noise less audible, it would make it worse, and the car wouldn't probably drive properly anymore.
    KiwiME, BlueSal, BC-Doc and 1 other person like this.
  20. MGrognon

    MGrognon New Member

    I've noticed (and others have pointed this out I think too) that this actually seems to vary from day to day and seems, for me at least to some extent, weather dependent. It's always there, but sounds worse on hot / dry days and seems less noticeable on colder / rainy days. That could very well be just pure luck/random or that for instance, there are more noises when it's raining that hide the hissing but at the same time it really does seem to vary as some days, I can barely hear it with windows open while on other days, windows closed and AC on I can clearly hear it inside the car when accelerating, decelerating (regen) or braking. I assume too that my sound sensitivity can vary from day to day mind you, but still ; odd. Especially if as others pointed out this is how the motor is designed and this is supposed to be constant.

    Speaking of which, I respect and understand other points of view mentioned above and I won't pretend to have the level of knowledge that obviously some of the other posters have when it comes to electrical motors or sound frequencies... All I can refer to is what I hear and I think all people are trying to do in this thread as pointed out by OP is figure out if this annoying sound is present on all Konas (in which case, to some extent case closed) or not (in which case ; it'd be great to figure out what this sound is, why some have it / don't have it and what to do to fix it, if anything).

    I'm on different Facebook groups that discuss the issue, and it definitely seems like some people genuinely DO NOT have this sound on theirs. Whether this is only a matter of auditory acuity / which frequencies some people hear or don't hear, don't know either.
    BlueSal and Brennan Raposo like this.

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