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3.0 Battery Longevity

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

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  1. gregd

    gregd Active Member

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    I think it's closer to 80% where balancing is triggered. According to the logs, standard charge on my car gets to 83%, and that's sufficient for balancing purposes.
     
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  2. BryanJ.Greene

    BryanJ.Greene Member

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    Thank you for replying.
     
  3. wycolo

    wycolo Active Member

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    A phone is dead in a matter of days - down to its cut-off voltage, so it doesn't matter what you charge it to. My iPod_5 went for 7 months and then returned to useful service. ModelS went for over 2 years and recovered fully. Tesla Roadster seems to be the only Li-Ion appliance that bricks its battery due to lack of cut-off circuitry.
    --
     
  4. ion_1

    ion_1 Member

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    Almost all Li-ion batteries produced today, except certain medical grades, will permanently fail if stored for extended periods at full discharge. It is a fundamental issue with the chemistry that will eventually be addressed. You are correct, proper cut off circuitry buys you much time, but eventually parasitic self discharge can drain the cell to full discharge and cause an issue. Depends on when you cut off, ambient temps, and parasitic load.
     
  5. BryanJ.Greene

    BryanJ.Greene Member

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    Both of you are right, I think I need more information and experience about car battery.
     
  6. bolosky

    bolosky Member

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    I haven't made an update in the graph for months. It seemed like doing updates with only a little new data didn't add very much.

    However, it's been four months now and I think it's time. If folks would send me their data, I'll do an update in about a week, and maybe we'll get a little more insight into what's going on as the packs age.
     
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  7. backmost

    backmost Member

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    I'll send my updated data hopefully sometime this week.
     
  8. dpeilow

    dpeilow Moderator

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    I'll try to send in an updated log file this week. About time we made another - it's been a year since I sent in the letter and still no formal response other than "we'll get back to you".
     
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  9. bolosky

    bolosky Member

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    Thanks. So far, I've only gotten an update from Steve Casner, so I'll hold off posting the update for a little while until I get yours and perhaps a few others. I think one's coming from Dave Denhart, and he has one of the other high mileage 3.0's, so his data will be really interesting.
     
  10. dhrivnak

    dhrivnak Active Member

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    I will send but not many miles since I last sent. For now my Roadster is mostly a summer car.
     
  11. utch

    utch Member

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    My roadster has been parked for the winter.
     
  12. slcasner

    slcasner Member

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    That might make it an interesting data point.
     
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  13. utch

    utch Member

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    Yes, I also think it will be interesting. I'll pull the logs but it may have to wait until late April.
     
  14. bolosky

    bolosky Member

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    Don't bother until you've driven it a little. The CAC algorithm doesn't update at all when the car isn't driven, so all I'll get will be the same value over and over. What it updates to once you've put a few dozen miles on it will be interesting, though.
     
  15. bolosky

    bolosky Member

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    OK, here's the update. I've got new data for 33, 181, 277 (EU), 330 (EU), and 670, which happen to be the five highest mileage cars in the study. I also added a new car, #417.

    My car (670) has bounced around some, but looks like maybe it's stabilizing around 180Ah. I think that it may have taken that long for the algorithm to fully realize the damage that happened from letting the cells get too low in the fall, and if so it cost me 10 Ah (ouch!). I notice that #181 looks like it's hitting a plateau at roughly the same mileage that I did for that big flat-ish period from 16K-35K miles. Alas, it was in an accident and isn't back on the road yet, so it may be a long while before we get more data on it.

    #33 is an outlier in terms of loss of capacity vs. miles, but it's about where my car is based on time. 277 (EU) is tracking #181 quite well, I'll be interested to see if it plateaus at the same point in another few thousand miles. 330 (EU) is tracking 670. The big drop in CAC around 10K miles corresponded to some very long drive days, which may also mean very low SOC, which has been known to lower the CAC. It's maybe 5K miles short of where 670 and 181 plateaued, so it will be particularly interesting after the end of the summer when it's got a few thousand more miles on it.

    417 (the new addition) is a pretty low mileage car, with less than 2K on the 3.0 battery. It's got a big hole in its log file, so the ~700 miles in two day that it looks like it has is an artifact. It's doing a little worse than most of the low mileage cars, but it's also got a lot of calendar time on the battery.

    Thanks everyone for the data. I'll probably hold off on doing another update for a few months, unless I get tons of logs in.

    CAC vs. Mileage.jpg CAC vs. Days.jpg CAC vs. Mileage zoomed.jpg 670 3 batteries.jpg
     
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  16. backmost

    backmost Member

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    I've been trying to pull the logs but the VDS keeps giving me memory stick issues. I've got the VehicleLogs folder on the root directory, FAT32, 4 GB, etc. Do I have to reset the VMS? I tried the charge port trick but it didn't seem to work.
     
  17. bolosky

    bolosky Member

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    You could try that. Or maybe you have a bad memory stick, often they're pretty low quality.

    What's the error you're getting?
     
  18. ChargeIt

    ChargeIt Member

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    The memory stick needs to be formatted as FAT16. In order to format a 4GB stick as FAT16, a 2GB or smaller partition has to be created on the stick first. Then that smaller partition can be formatted as FAT16.
     
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  19. backmost

    backmost Member

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    I currently have it at FAT32, which is weird since it worked last time with no issues.

    The error is just the VDS saying unable to save data to memory stick or something along those lines.
     
  20. dpeilow

    dpeilow Moderator

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    • Informative x 1

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