eNate
Posts: 642
Joined: Mon Sep 09, 2019 5:33 pm

Re: Resonant hum

Sun May 09, 2021 5:19 am

alohart wrote:
Sun May 02, 2021 6:29 pm

... at higher charge levels, an i3 might be mimicking pure regen braking power at lower charge levels by blending lower regen braking power with friction brakes.
I'm not aware of the friction brakes being applied in the absence of regen. If my 2017 can't regen (usually at 100% charge or on a chopy road or pothole) it gives me nothing when I lift off, and just coasts.
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alohart
Posts: 2368
Joined: Sat Nov 01, 2014 7:36 pm
Location: Honolulu, HI

Re: Resonant hum

Sun May 09, 2021 11:27 am

eNate wrote:
Sun May 09, 2021 5:19 am
I'm not aware of the friction brakes being applied in the absence of regen. If my 2017 can't regen (usually at 100% charge or on a chopy road or pothole) it gives me nothing when I lift off, and just coasts.
Those who live at the top of hills have reported that friction brakes mimic regen when the power pedal is lifted at a very high charge level. I don't live at the top of a hill and don't usually charge to 100%, so I don't have much experience with this behavior. However, when I have charged to 100%, I've never been surprised by the lack of regen which I'm pretty certain I'd notice living in the suburbs with lots of traffic lights.
Aloha,
Art

2014 BMW i3 Arravani Grey, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, JuiceBox EVSE

eNate
Posts: 642
Joined: Mon Sep 09, 2019 5:33 pm

Re: Resonant hum

Sun May 09, 2021 11:49 am

I'm at a disadvantage too, because I rarely charge to 100%, and when I do, it's at work on the flatlands. But on those rare instances, I have noted (with alarm!) an unmistakable lack of regen approaching intersections.
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OLDBMWGUY
Posts: 18
Joined: Tue May 28, 2019 12:32 am
Location: Honolulu, Hawaii

Re: Resonant hum

Mon May 10, 2021 11:32 am

I think I can confirm that the regen is inhibited when the BEV is fully charged and going downhill.
After a full charge, 99% and 173 miles range, my 2019 I3 BEV had (unusually) very little regen going down a steep hill at my location. Brakes seem to work normally.
The next time down the hill, later that day, at 94% and 151 miles range, the regen was back to normal.
2019 i3 BEV, Capparis White, Tera World, Harmon Kardon Audio System, 19 inch 429 wheels

Fisher99
Posts: 401
Joined: Sun May 12, 2019 6:24 pm

Re: Resonant hum

Tue May 11, 2021 6:54 pm

Yes, I can also confirm. I live at the top of a steep, 4 block long, hill with a stop sign at the bottom. With full charge the i3 slows a bit when I lift off, but I still need to use the brakes at the bottom. With a lesser charge (seems to be in the 92%-95% and below range) the regen slows me to a full stop.
2014 BMW i3 with Range Extender Engine, Capparis White/Frozen Black, 20" wheels,, Giga World, Tech + Driving Assist, Parking Assist, DC Fast Charging, TurboCord EVSE

willmhull
Posts: 13
Joined: Sun May 02, 2021 11:35 am

Re: Resonant hum

Wed May 12, 2021 1:32 pm

UPDATE

Tried to move the front to back - back to front at home and a few of the lugs are cross-threaded. I sent an online reply to a customer service survey request and I had not heard anything, so I called BMW. A technician came to my house and tried to remove the tires and could not. Now, I am scheduled for a service visit tomorrow.

Although the tech is skeptical about the tire causing the sound, I am pretty sure the misplaced tire is the problem. The space between the suspension coil and tire is tight (you can hardly fit a finger in there). Further, I noticed that the sound was much worse and frequent when my overweight friend was riding shotgun. It also commonly occurs when I am stopping on a hill--I imagine the coil is compressed in this situation as well probably expanding and rubbing on the tire. Although, it does sound more metallic...

All told, it should be taken care of tomorrow.

eNate
Posts: 642
Joined: Mon Sep 09, 2019 5:33 pm

Re: Resonant hum

Thu May 13, 2021 10:34 am

I hope this is all covered. Since BMW was last to touch it, and the inspection should include a look at the brake pads, the cross threaded lugs at minimum should have been caught. Whether the tech was responsible, or responsible for noticing, that the tires were crossed, well, that's almost a secondary issue to damaged threads. But if the cross - up was preexisting, the tech might have noticed unusual wear on the inside sidewall.

This, of course, implies the wheels were actually removed to inspect the pads, and the checkbox wasn't just pencil whipped.
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willmhull
Posts: 13
Joined: Sun May 02, 2021 11:35 am

Re: Resonant hum

Sat May 15, 2021 9:33 am

They brought it in for service last week, moved the tires, and inspected it. Unfortunately, the technician I have been in touch with wasn't there, so I have to call on Monday to see what he found in the inspection.

It hasn't been humming since, so it was probably the issue.

eNate
Posts: 642
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Re: Resonant hum

Sat May 15, 2021 9:42 am

What about your cross threaded lugs?

Did they find any wear on the inner sidewall?
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willmhull
Posts: 13
Joined: Sun May 02, 2021 11:35 am

Re: Resonant hum

Mon May 24, 2021 2:55 pm

eNate wrote: What about your cross threaded lugs?

Did they find any wear on the inner sidewall?
They didn't report any inner sidewall wear when I asked them about it, which I thought was odd. They fixed the lugs, and relocated the tire. I am happy with that. Still going without the noise.

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