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Tesla Infinite mile battery pack (rated range stuck)

Discussion in 'Model S: Battery & Charging' started by yobigd20, Jul 29, 2015.

  1. yobigd20

    yobigd20 Well-Known Member

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    #1 yobigd20, Jul 29, 2015
    Last edited by a moderator: Mar 13, 2016
    This morning I 100% range charged to 245 miles. After about 5 miles of driving normally I noticed my rated range didn't move at all, yet my avg Wh/mi was around 330. Not like I was going downhill or anything. So I decided to take out my phone and start recording. Video starts when I was at 6.7 miles in already with rated range staying at 245 the whole time. I finally got to 10.2 miles before it started dropping. Really practically 10 free miles. Why didn't the rated range just say 255 instead of 245? Software bug or some sort of weird programming algorithm?




    So I guess then if my 100% range charge is actually 255 instead of 245, this really makes everybody's answer in the multitude of TM/TMC threads and facebooks posts and google groups for 'what is your max range charge after xxxxxx number of miles' completely irrelevant. Who knows now since the display is no longer accurate and now we get free miles apparently....

    (also, ignore the creaking in the car, it was fully packed with boxes and chairs lol)
     
  2. qwk

    qwk Model S P2681

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    This is why all of those studies/polls that compare battery capacity for the Model S are worthless at best. I have said this from the get go. There are way too many variables to account for, and most of the relevant information is not given to the user.
     
  3. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    I reported a strange phenomenon the other day as well, where the "since last charge" stuck for about 15 minutes (@75 mph), then jumped 12 miles over the next couple of minutes (it should have been closer to 18-20). During this time, the odometer updated properly and I saw a decrement of rated range, but it still unnerved me that some of the displays were sticking, and that we are using them to try to do calculations on this forum.

    So it's clear that we can't really rely upon the instrumentation that's provided.
     
  4. apacheguy

    apacheguy Sig 255, VIN 320

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    And what info would that be? Is CAC the gold standard for measuring capacity?
     
  5. AmpedRealtor

    AmpedRealtor Active Member

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    I believe anyone can call their service center and ask for a CAC value for their car.
     
  6. Scotty

    Scotty Member

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    Last week, I saw the same thing. I supercharged to about 245 miles, and I drove about 9 miles before it started dropping.

    Scotty
     
  7. gavine

    gavine Petrol Head turned EV Enthusiast

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    Same here. Fully charged my 60 the other day for the first time in a long time. The rated range was only showing 180 miles. It stayed at 180 for about it 6 or 7 miles before it started to drop. I drove 183 miles (+/-) and got home with 20 miles to spare so that's more like 203 than 180. I probably oils have had a more accurate reading had I used ideal range display because it was mostly highway miles.
     
  8. apacheguy

    apacheguy Sig 255, VIN 320

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    Never tried this. Would be easier (and cooler) if they gave us read-only access to the diag screens.
     
  9. invisik

    invisik Member

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    I've seen similar behavior with the rated miles number not going down for a little while after charging to 100%. Definitely it is trying to recalibrate the rated mile number to the actual capacity of the battery pack and is normal. My 100% charge last year was 265 and this year it was 249 (I usually charge 50%-60% so the calibration is way off on the top end)--I still arrived in that segment with the exact number of rated miles left as I had the previous year (similar conditions too). So the battery capacity is just fine.

    If one e-mails ServiceNA will they give you your CAC number?

    -m
     
  10. pgiralt

    pgiralt Active Member

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    I've seen this happen before, just not quite so many miles. The most I've seen is about 5 miles. I think this is just the software trying to re-calibrate after the range charge. Usually if you range charge again after that, you'll actually see some of those extra miles show up. This is why lots of people say they increase their rated range by range charging. It's just the software trying to figure out the actual pack capacity, not to mention any kind of balancing that occurs when you range charge.
     
  11. supratachophobia

    supratachophobia Active Member

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    What is a CAC number? I will extremely disappointed if it's just Mark Walberg being vulgar.
     
  12. AmpedRealtor

    AmpedRealtor Active Member

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    ^^ this is a great idea!

    - - - Updated - - -

    CAC=Calculated Amp-hour Capacity

    - - - Updated - - -

    Strange... over the last couple of days, my 90% charge has crept up from 227 miles to 230 miles. Range mode is off.
     
  13. supratachophobia

    supratachophobia Active Member

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    That is a great idea, I already feature requested it a few weeks ago, you all should too.

    And is this CAC number available to owners for real? And is it accurate to determine battery degradation?
     
  14. Ingineer

    Ingineer Electrical Engineer

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    These momentary stalls and sudden adjustments are due to the way the pack tracks it's state of charge and capacity. They use a current shunt to "coulomb count" which is basically counting the amps in/out. Problem is this is not 100% accurate and subject to drift and slight tracking errors. So the system will correct for these errors occasionally when known voltage curve targets are made, such as when performing a range charge.

    We also have the CAC tracking which is constantly tracking the estimated capacity of the pack. This is needed to calculate the SoC by using the coulomb counting measurements. Both CAC and the SoC algorithms depend on occasional full charges to reset their accuracy.
     
  15. AmpedRealtor

    AmpedRealtor Active Member

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    I believe your service center should be able to provide you with a CAC number for your battery.
     
  16. mknox

    mknox Well-Known Member

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    Mine will almost invariably drop quite quickly at first. If I leave the house with 215 Rated Miles @ 90%, I might be down to 210 or 211 by the time I've driven a mile. On the other hand, I usually do quite well on the Wh/mi front. Without even trying, my July number was 303. My all time monthly low was 287 in June of 2014 going a bit over 3,000 miles that month.
     

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