"Milling Noise" or "Leaking Balloon" Sound

Hmmmm.....it doesn't sound that loud in the video but I am sure it's annoying in person.

I had this sound, which Tesla said was normal. It started after I had the 12v battery replaced.

Tesla Model S Whine Noise - YouTube

Sounds like milling to me. Ask them to take a recording and send it to HQ. The balloon squeal only happens for a few seconds on hard acceleration and is kinda fun. Milling sound is ever present, sounds like a bad electrical transformer, and is really annoying.

Definitely sounds like milling to me. As Rick says, take it back to the service center and ask that they take a recording and send it to engineering. Take the person with the recorder on a test drive and reproduce the problem for them.

Milling noise is not normal under any circumstances and portends a drive unit failure in the future. Whoever said that to you at service is not doing their job properly. I would contact the service manager and ask for a second look.

AmpedRealtor said:

Milling noise is not normal under any circumstances and portends a drive unit failure in the future. Whoever said that to you at service is not doing their job properly. I would contact the service manager and ask for a second look.

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^^^this. i've had 4 drive units replaced for milling noise.

I had a drive unit replaced on my May 2015 build Model S. The noise I had was louder. I had a 2013 Model S which had a balloon squeal but I liked it and never took it in, so I don't know what Tesla would have said about that. I thought it was funny as hell. But I can't hear a balloon squeal in your recording, or a milling noise. But it could be my ears or the recording.

I wouldn't worry, because if its a bad DU the noise will get worse and they'll replace it. Give it a few months.

I've had the same sound for quite a while, although it hasn't gotten that much worse in the last year. It's still there and annoying though. I tried to boost the particular sound in my recording to make it stand out more:


I'm holding out for the day when they finally have a DU version that absolutely solves this. I've seen mixed reports with the current DU revision.

Agree that this is the milling sound and should probably warrant a DU replacement. For clarity, it is not the leaking balloon sound, which is much more obnoxious and was fairly common on early cars. I haven't heard of any cars built in the last 2 years or so that have exhibited the leaky balloon sound.

Drive unit, can confirm the noise is the same.

Todd Burch said:

Agree that this is the milling sound and should probably warrant a DU replacement. For clarity, it is not the leaking balloon sound, which is much more obnoxious and was fairly common on early cars. I haven't heard of any cars built in the last 2 years or so that have exhibited the leaky balloon sound.

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June 2015 85D here, and I've got the leaky balloon sound on acceleration. Service center said it was battery contactor squeal and that it was normal.

2013 P85 w/ squealing contactors, was told by service today that it's normal and within spec. I suppose the issue is settled for now.

"Squealing contactors" since day one.

qwk said:

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Good definition of the famous balloon squeal. All that technical mumbo jumbo, when we really know the car is just going "Wweeeee!" Because it likes to go fast too!

Although, in my car the sound seems as if it is coming from up front near dash area, not rear of car.

I don't have a D either so the front is just rolling, not pulling.

The noise I got my drivetrain replaced for is not this squeal. Had the squeal before and after the swap. Same battery pack, so makes sense.

The noise calling for a motor swap is best recreated by quick jabs at modulating to go pedal between 0 and 40kw on the orange power delivery scale, while rolling at 30mph or so. The sound pitch is proportional to pedal position and power outlay and swing of that orange arc. The loudness increases over time. Note, this sound is not proportional with rolling speed of the car. You can create the same musical variations at any speed so long as you're delivering power in that same range.. it's just easier to hear or more noticable at slower rolling speeds before wind noise and road rumble kick in to help drown it out.

eyespii said:

June 2015 85D here, and I've got the leaky balloon sound on acceleration. Service center said it was battery contactor squeal and that it was normal.

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Interesting. My Oct 2014 P85 and a loaner I had during my first annual didn't have the squeal. I thought it'd been "fixed", but maybe it's just luck of the draw.

1. September 2013--wonder if there isn't something newer to update this information.

2. Never read anywhere here about stator winding delaminations--probably some other public forum?

3. If contactors are vibrating then it seems to me that arcing plasma would damage the ultra-low-resistance contacts. Maybe that's what inconel damping springs are intended to solve...
edit to add patent reference: switch with damping

just my 1¢, bandwidth is half-price today.

kennybobby said:

3. If contactors are vibrating then it seems to me that arcing plasma would damage the ultra-low-resistance contacts. Maybe that's what inconel damping springs are intended to solve...

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Exactly what I believe as well. I have been wondering if anyone with a 90 kWh battery has experienced the balloon squeal yet. Probably not.

I have a low vin (5xxx) 2013 and had a higher (21xxx) 2013 as well. My high vin car was silent however my low vin car has made a whining noise since I picked it up a couple months ago. The noise isn't obnoxious or very loud but it occurs under any throttle application and regen as well. Having not heard the milling noise, I assumed this was it. So a Tesla tech went on a ride with me and told me that it's absolutely fine. He was actually surprised that my other car made no noise at all.

This comes as a bit of a surprise to me as the first car I rented made no noise, my first high vin car made no noise and even the P85+ loaner Tesla has me in makes no noise. Nonetheless, they replaced the drive unit for me but have assured me throughout that the only reason they replaced it was because of my noise complaint. I wonder how many people are mixing the milling sound noise with regular whining and are assuming their DU is failing. Tesla's willingness to replace the drive unit for no other reason than a noise complaint might serve to back up their assumptions too.