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How long until excessive battery temps effects show up?

Discussion in 'Roadster: Technical' started by sethr, Jan 3, 2017.

  1. sethr

    sethr CPO Roadster #1089

    Joined:
    Mar 24, 2013
    Messages:
    175
    Location:
    Fairfax, VA
    Recently, I was in an accident, and my Roadster was in the hands of Dorn's Body & Paint for 15 weeks. It was exposed to high temperatures for an unknown period of time, with the "battery loop" disconnected while in the paint booth. Dorn's said different things at different times, though they did admit one time to exposing it to 118 F, but not for how long. I sent Tesla the downloaded logs (before my appointment to check things out and replace the charge port door which Dorn's broke and glued back, which lasted a few days), but Tesla will not tell me precisely what is in the logs, though they did "check the logs for temperature issues" and performed a "battery test", and found "no issues". But I do not know exactly what temperature the battery reached or for how long, or if there are any gaps in the logs since things were disconnected. Apparently these details will not be made available to me, and I'm too much a computer dunce to look at the logs myself (I did try, couldn't figure out how to do it). Standard charge was getting me 185 - 186 miles, and now it's 181 - 184. BUT, ambient temperatures are 30 degrees lower now, so I guess that's apples to oranges. Sorry for the long preamble ramble; now here's my question: if my Roadster's battery was a over ideal temps for some period, would any damage to its capacity show up right off, or could it end up manifesting itself some time later? Any idea how long it could take? Thanks in advance for any insight.
     
  2. MileHighMotoring

    Joined:
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    Location:
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    First, I doubt 30 minutes at 120 degrees is going to hurt the batteries. Paint shops bake cars because it turns a 12 hour cure into a half-hour cure. So it's quick and not a prolonged process from my understanding.

    That, and your experience showing around a 1% change in the battery is probably proof enough that no damage occurred to the pack.

    I wouldn't worry about it. It doesn't sound like you had a CAC number already from before the work being done, that would have been a better data point instead of the miles shown on the screen, but honestly I think it's unnecessary anxiety.
     
    • Informative x 1
  3. sethr

    sethr CPO Roadster #1089

    Joined:
    Mar 24, 2013
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    Fairfax, VA
    My CAC was 156.41 before, I just haven't taken a long enough drive for it to reset itself yet. I have no idea how long they had it in the paint booth: they did some other things wrong, and told me different stories at different times about several other things, so I wouldn't count on it only being 30 minutes. But my question is only whether there are long term effects that show up later.
     
  4. supersnoop

    supersnoop Tesla Roadster #334

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    Pflugerville
    118 degrees shouldn't be a problem. When they start getting into the 140-160 degree range, you need to worry. I think there's even a sticker on the car, near the tire pressure sticker, that lists the maximum temperature and duration for the battery.

    That said; my Tesla-certified body shop had the battery removed before they put the car in the paint booth.
     
    • Informative x 1
  5. apacheguy

    apacheguy S Sig #255

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    What was the SOC? If less than 50 I wouldn't worry at all.
     
  6. ion_1

    ion_1 Member

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    Aug 11, 2016
    Messages:
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    Location:
    NJ
    Very interesting point about paint booth bake cycle and the battery.
    The situation is not ideal, but I have never seen a delayed effect of high temperature. Capacity loss on single Li-ion cells show up within 1 cycle mostly due to chemistry repair at the interface and interphases of the electrode materials which consume Lithium. 50 degrees Celcius is a little toasty for Li-ion but for short amount of times (<few days) it should be fine as tests are done at 45 degrees and 60 degrees for months at a time at all states of charge. If anything there may have been a minimal increase in cell impedance (resistance) which may not be evident at the rates you are charging and discharging the battery. Sitting there for 15 weeks may induce some cell balancing and recalculation changes, but they should sort themselves out. That said, such conclusions are very cell chemistry specific and it is hard to generalize especially as a battery ages.

    There has been a number of paint repairs in the roadster community, it would be interesting if anyone has knowledge of their
    bake time/ temp and whether any changes occurred afterwards.

    In the meantime, don't stress. It's not worth it. As milehigh stated 1% is in the noise until you look at the long term trend before and after. Especially with 30 degrees lower ambient temp. This could definitely temporarily lower the CAC. As you know from the fine postings in this forum CAC is not an exact measure of your capacity anyway. Long term (months) trends are important, ignore the short term data.

    Sorry to hear about your accident.
     
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