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clunk from battery area after climbing 2000ft (600m)

Posted: Fri May 29, 2015 9:09 pm
by achewt
I drive up to a local mountain town about once per week; it is a 600m climb (2000ft) over only 8km (5miles). Most of the climb is done at about 70km/hr (45mph). During the winter I started noticing the occasional "clunk" sound from the battery, seemingly under my seat, just a minute after I slowed down to enter the town. It didn't happen every time, and it was during winter, so I thought it was that frozen slush stuff falling out of the wheel well and clunking against the under side. Fast forward to this spring, and this noise still happens about 50% of the time! I haven't noticed it correlating to anything in particular yet (e.g. temperature outside, how fast I drive up the hill, etc).

I really haven't been able to figure it out and the nearest Leaf dealer is a 2-day drive over 350km (terrible infrastructure here!)

The noise is always one single clunk, and is to the point that I usually can 'feel' the sound through my seat as well as hear it. The only explanation I can come up with is rapid heating of the battery from the climb after the car has been sitting around at work all day, causing some sort of expansion.

Anyone else experience a similar phenomena? I searched the forums for clunk and found a fair amount about something to do with the drivetrain, but I don't experience this sound at the same time.

Re: clunk from battery area after climbing 2000ft (600m)

Posted: Fri May 29, 2015 9:17 pm
by abasile
That's a mystery to me. I've often done a 1500m (4900') climb over 23km, which often leads to one "bar" of battery heating, and have never heard such a clunk.

This vaguely reminds me of drivetrain symptoms that some Tesla owners have reported.

In case anything worse happens, you should be covered under the powertrain warranty which in the US ends at 60,000 miles IIRC; I don't know what the terms are in Canada.

Re: clunk from battery area after climbing 2000ft (600m)

Posted: Fri May 29, 2015 9:22 pm
by achewt
I think our warranty is pretty similar. I find it odd too, since I was climbing 1,100m (3,600ft) every weekend, sometimes twice, to go to our local ski hill and never once noticed it there. However that is on a bumpy snowy road, so maybe I just didn't hear it. I've only noticed it climbing from Trail to Rossland (the hill noted in the first post).

Re: clunk from battery area after climbing 2000ft (600m)

Posted: Sat May 30, 2015 10:36 am
by TonyWilliams
Some relay opening / closing? I can't think what relay it could be, however.

Re: clunk from battery area after climbing 2000ft (600m)

Posted: Sat May 30, 2015 1:52 pm
by achewt
I will try and get an audio clip of it this week

Re: clunk from battery area after climbing 2000ft (600m)

Posted: Sat May 30, 2015 2:14 pm
by RegGuheert
I wonder if it could be a piece of sheet steel "oil-canning". Usually such things are prevented by putting ridges in stampings, but who knows?

I've never heard such a thing, but my largest climb is about 200m over 2 miles.

Re: clunk from battery area after climbing 2000ft (600m)

Posted: Wed Sep 09, 2015 5:03 pm
by achewt
So I have experienced this clunk several more times since starting the thread several months ago. Of course Murphy is laughing at my efforts to record the sound of it. It is definitely related to prolonged use of > then 20 or perhaps 30 kW associated with climbing the mountain passes of southern BC at highway speeds. On my most recent experience last weekend, there was also a vague 'hot electrical' smell wafting from under the car. I'm not really sure what is happening down there, but my nearest dealer is a 380 km, 2 day drive away... so not exactly convenient to get it checked out!

Re: clunk from battery area after climbing 2000ft (600m)

Posted: Thu Sep 10, 2015 10:45 am
by Nubo
I'm wondering if it's related to air pressure? That would be consistent with a single noise, like your ears popping... I know the battery pack is sealed, but maybe there's a pressure-relief valve somewhere? I don't recall hearing about this from other mountain drivers though.

Re: clunk from battery area after climbing 2000ft (600m)

Posted: Thu Sep 10, 2015 1:21 pm
by JeremyW
If it's anything electrical, the only things that go clunk on a regular basis are the various battery contactors. "Hot electronics" smell makes me think you may have a failing contactor.

Re: clunk from battery area after climbing 2000ft (600m)

Posted: Thu Sep 10, 2015 8:23 pm
by achewt
A cursory google search turned up this page (http://www.lithiumbalance.com/powerswit ... or-control). So if I have some individual cells that are overheating due to the sustained power draw and the contactor opens, does it reclose later? I've had this happen a good dozen times now, and no noticeable battery capacity loss or dummy lights on the dash. I don't have Leaf Spy, but maybe I should get it to check the health of each of the cells?