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3.0 Battery Longevity

Discussion in 'Roadster' started by bolosky, Feb 14, 2017.

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  1. dpeilow

    dpeilow Moderator

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    It certainly will - it looks like it is coded to start at 215.xx until it finds the real pack capacity.
     
  2. bolosky

    bolosky Member

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    I've been remiss in posting updates for a while, because of some personal and work issues. As a result, this update contains data for five cars: 670, 541, 505, 573 and 330. 573 is a new car, with a typical low mileage profile.

    Nothing especially surprising has shown up. I've been range charging my car (670) for the past few days, and its CAC has climbed like it always seems to do. I'll keep doing it for a while to see if that levels off.

    One new addition is that I've added a zoomed in version of the by mileage graph. A few of the high mileage cars have expanded the graph enough that it's really hard to distinguish the stuff in the upper left hand corner where the bulk of the lines lie. So, I've just clipped it to 5K miles and 15 Ah of CAC so you can see it better.

    CAC vs. Mileage.jpg CAC vs. Days.jpg CAC vs. Mileage zoomed.jpg
     
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  3. bolosky

    bolosky Member

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    Oh, and thanks so much to thebabydoc, dpeilow, utch and simonog for supporting this project with their data!
     
  4. dpeilow

    dpeilow Moderator

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    That's strange - when I last sent you a log file the CAC on the car's display and OVMS was showing 212.57, including for a few days afterwards. Then I went for drive and it finally recalculated to 212.19 after weeks of being stuck at .57, but it looks like your graph has the lower number in it.

    Also, where is 277 EU in the CAC vs. Time graph?
     
  5. gregd

    gregd Active Member

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    So, the gradual slide into Oblivion continues unabated?
     
  6. bolosky

    bolosky Member

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    Pretty much.
     
  7. DeedWest

    DeedWest 2010 Roadster 2.0 - VIN 523

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    I helped a friend sell his 2.5 Sport with R80 to a guy in LA. I'll try to contact him and see if he'd lend his data to the thread. It would be interesting, because when I borrowed the car and got to drive it a few times, it would charge to 198 in Standard Mode and the CAC was in the low 190's - all with the car's odometer around 9,000 miles. Pretty disappointing if these batteries are degrading this quickly, and without even the usage or mileage having the largest adverse effect. It seems to be time in general, at least for his R80's sake.

    Also, who has VIN 002? That's awesome to see it on the graph.
     
  8. utch

    utch Member

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    I probably won't put many miles on until May: winter finally arrived and then some travel plans. However, I can update whenever you'd like.
     
  9. bolosky

    bolosky Member

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    I did a multivariate regression a while back, and it showed that time was a much bigger factor than usage, though both were important. So, if you compare 33 to 670, you'll see that 33 has only a slightly better CAC, even though it's at about a quarter of the mileage. Though to be fair, 33 would probably have its CAC go up a ton if it were range charged a few times.

    I don't know who has VIN 002. Someone other than the owner sent me the log file with little explanation. At first, I confused it with Founders' series #2, which is Martin Eberhard's car, but alas it's not.
     
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  10. bolosky

    bolosky Member

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    And just to put this in perspective: a CAC of 184 is midway between a new original battery and a new 3.0. Dave and I are pretty close to there.

    The good news is that most likely the car will still be better off with the 3.0 battery by the time that my 2020 Roadster shows up than it would have been with the original battery, though the range will probably be less than a new original battery by then. It'll just be better than my old battery with close to 200K miles would have been.
     
  11. dhrivnak

    dhrivnak Active Member

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    Bolosky, again thank you for doing this. And as 3.0 owner this is disappointing to see such a decline. But possibly, just possibly we may see an upturn as my old battery set always dropped a bit in winter to regain most of it during the summer. While our winters are not too bad it seemed like the Roadster was not happy with it.
     
  12. thebabydoc

    thebabydoc Member

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    Funny that you say that, My Porsche Cayenne e-Hybrid seems to lose almost 25% of it's range when it gets below 40 here...
     
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  13. dpeilow

    dpeilow Moderator

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    So I attended a Tesla UK "club house" event on Thursday evening and tried to raise this 3.0 longevity issue and the expense of replacing PEMs for even simple issues in the Q&A section with the Director for Western Europe on the night. I got shut down pretty quick and he suddenly had a doctor's appointment to keep (at 9pm?). It didn't help that I was the only Roadster owner in the room, the others that were due to come all sensibly bailed out thanks to the atrocious weather, but I also know there were several watching it online.

    Nevertheless it did get into the unofficial minutes for the event and his 2IC did speak to me afterwards and agreed to take it further if I put in writing what the issues are. As can be seen on the graphs above, mine isn't too bad yet, but I suspect that is more down to me not driving it much over the winter since my fix 6 months ago than anything else. My main intention is to get Tesla to acknowledge something is going on, ask if this is a real effect or a problem with the CAC algorithm / not being able to balance, perhaps get details on the cell type the used and ask (if it is a real effect) what the company wants to do about it.


    So @bolosky would you mind if I take the latest graphs and attached them to my communication to Tesla on this? If other owners are also willing to figuratively "sign" the letter, that would be appreciated, as the more weight behind it the better.
     
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  14. dhrivnak

    dhrivnak Active Member

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    I am willing to sign. Thanks
     
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  15. Msjulie

    Msjulie Member

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    me too

    I'm wondering how long it will be till the standard range of the 3.0 battery is no more than the original.. 220-225 is what I see now
     
  16. ggr

    ggr Roadster R80 537, SigS P85 29

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    I'm in.
     
  17. gregd

    gregd Active Member

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    For what it's worth, I raised this with the local SC about a year ago, including a reference to this thread. They said they'd pass it on, but I never heard anything back.

    I have not pulled the trigger to get the new battery, even though I would like to. It is specifically because of this observed degradation that I have not done so. You may quote me on that, if it will help.
     
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  18. slcasner

    slcasner Member

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    Sure for me, too.
     
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  19. bolosky

    bolosky Member

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    Go ahead and send the graph. Anything I post here is intended to be available to the general public (since it actually is).

    My preference with Tesla would be to try to work with them rather than being confrontational. I think it's more likely to work out. That said, if there's a problem with the cells then nothing is going to fix it, they are what they are. If it's a problem with the CAC algorithm or balancing, that's a different matter, maybe a little engineering/programming time would help.

    I'm not optimistic, though. My guess is that mostly it's a problem with the cells, and beyond that a slight problem with the algorithm being too conservative. I base this on the behavior when you range charge repeatedly: the CAC goes up for a while, then stops going up, and if you look at the tops on the per-mile graphs, they make a line, just one with a slightly flatter slope than when you don't range charge.
     
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  20. Mitrovic

    Mitrovic Member

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    I don t have the new battery, but I would sign, because the problem of the falling CAC is the reason why I have not yet bought the new battery.
     
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