TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker and becoming a Supporting Member. For more info: Support TMC

Battery charge level drops significantly after every firmware update

Discussion in 'Model S' started by T3SLA90D, Mar 10, 2017.

  1. T3SLA90D

    T3SLA90D Member

    Joined:
    Jan 5, 2017
    Messages:
    37
    Location:
    York, PA
    New Tesla S 90D delivered December 2016. After every firmware update, the battery charge level drops significantly about 20-30% compared to before the update while the car is parked and plugged in. An hour or 2 later, the charge level gradually goes back up to baseline. If the car is plugged in, it overrides the charge limit and end up at 100% even if it was set to max out at 80 or 90%. If the car is not plugged in, charge level eventually goes back to what it was before the update.

    Service center does not know what's going on. They called Tesla engineers and states that this is a normal behavior with the car trying the re-read battery capacity.

    Has anyone experienced a similar issue?

    Thank.
     
  2. smartypnz

    smartypnz Supporting Member

    Joined:
    Jan 23, 2013
    Messages:
    706
    Location:
    Monterey Peninsula
    You might want to research how that range is calculated.
     
  3. Nietschy

    Nietschy Member

    Joined:
    Oct 2, 2016
    Messages:
    75
    Location:
    Austria
    why should he?
    I never heard about this before. My charge level is exact the same as before the updates (I had about 6 already).
    If most/all responses are that way. He should should empower tesla to fix his car because it is not right. period
     
  4. trayloader

    trayloader Member

    Joined:
    Nov 21, 2016
    Messages:
    99
    Location:
    GERMANY
    Yes. Same here.
    7.1 was @ 384KM
    then
    379KM
    now @ 370KM
    within a mere 7000km of driving.

    ...
     
  5. T3SLA90D

    T3SLA90D Member

    Joined:
    Jan 5, 2017
    Messages:
    37
    Location:
    York, PA
    Thank you Nietschy

    Trayloader I think you may have misunderstood the issue. I mean that, for example, before the software update the battery level is at 260 miles. As soon as the update is installed the battery level shows 160 miles and then an hour later it goes to 200 and then another hour later it's back at 260 miles without having driven the car.
     
  6. trayloader

    trayloader Member

    Joined:
    Nov 21, 2016
    Messages:
    99
    Location:
    GERMANY
    Sorry if I was not clear.
    384 was at 7.1
    379 was right after 8.0 first update
    370 after the latest.

    I should've stayed at 7.1
     
  7. ucmndd

    ucmndd Member

    Joined:
    Mar 10, 2016
    Messages:
    366
    Location:
    California
    Same here. I dropped 10% after installing the latest update yesterday.

    I don't think there's any cause for concern.
     
  8. Btrflyl8e

    Btrflyl8e Supporting Member

    Joined:
    Mar 24, 2013
    Messages:
    2,528
    Location:
    Seminole, Florida, United States
    Simple solution, don't check until at least 2 hours after an update!

    I don't know that I've ever paid attention to the rated miles showing immediately after a software update...and I've had dozens. Seems odd, for sure
     
  9. T3SLA90D

    T3SLA90D Member

    Joined:
    Jan 5, 2017
    Messages:
    37
    Location:
    York, PA
    Update on the fix for the record in case others experience a similar issue.

    SC fixed the problem with the following description
    "Corrections: HV Battery Assembly General Diagnosis

    Issue caused b fault in battery management system circuit board. Corrections: Battery Management System (BMS) (HV Battery 2.0)

    Replaced BMS circuit board."

    I since insltalled a firmware update with no issues
     
    • Informative x 2
  10. ShockOnT

    ShockOnT Quickish

    Joined:
    Jun 26, 2016
    Messages:
    1,034
    Location:
    Sydney
    Glad it's resolved.
    Just FYI, the miles range is not really battery capacity. You need to change units to "energy" to show percentage. I'd be curious to know if they actual percentage was dropping that much.
     
  11. TexasEV

    TexasEV Well-Known Member

    Joined:
    Jun 5, 2013
    Messages:
    5,090
    Location:
    Austin, TX
    No, both the range and the percentage displayed are estimates, as battery capacity can not be measured directly. Toggling the display will just change units from rated miles to percent. One is not more accurate than the other. For example, if a battery with 200 miles rated range shows 100 miles range on the display and you toggle to percentage, the car will display 50%. Of course that doesn't mean you will be able to drive 100 miles, just that the battery is estimated to be 50% full either way.
     
  12. ShockOnT

    ShockOnT Quickish

    Joined:
    Jun 26, 2016
    Messages:
    1,034
    Location:
    Sydney
    I thought rated miles was one step further extrapolated?
    ie. percent is an estimate of coulombs of charge remaining, and rated miles is an estimate of range using percent and driving history.
    At least that's how I thought it worked...

    Eg, if the battery is 50%, it might show a rated range of 100 miles for someone who drives like a maniac, but the car next door might show 120 miles even though it was also at 50% (with same pack size).
     
  13. tpham07

    tpham07 Member

    Joined:
    Mar 21, 2017
    Messages:
    459
    Location:
    Baton Rouge
    The number you see on the dash is the computer estimating how much range is left in the battery. Its a "guess." When you reset a computer (i.e. during a firmware update which installs brand new software) then its perfectly normal to expect these systems that calculate things to start from scratch.
     
  14. ShockOnT

    ShockOnT Quickish

    Joined:
    Jun 26, 2016
    Messages:
    1,034
    Location:
    Sydney
    That's why I was curious to know percentage rather than rated miles.
    I can understand rated miles changing after a reset, but I would have thought that percentage would be calculated from some physical (non-resettable) attribute of the battery, such as pack voltage or internal resistance.
     
  15. Mediocrates

    Mediocrates Member

    Joined:
    Apr 16, 2017
    Messages:
    63
    Location:
    San Diego, CA
    Do you have a source for this hypothesis that explains why a Tesla battery/subsystem would be different in this regard versus every other battery-powered piece of technology that has been in the hands of consumers for decades?
     
  16. stopcrazypp

    stopcrazypp Well-Known Member

    Joined:
    Dec 8, 2007
    Messages:
    8,776
    #16 stopcrazypp, May 14, 2017
    Last edited: May 14, 2017
    Instantaneous measurements are not a reliable way of getting battery SOC, since this varies with age and conditions (a lookup table that factors those things in helps somewhat, but can't be completely relied on). Some form of coulomb counting and battery learning/history (to calibrate to prevent drift) is required to get a decently accurate estimation. These factors can be reset (and thus require re-calibration). See links below for details on how its done.

    All battery percentage calculations are only an estimate (Tesla's included). The only true way to get accurate capacity is a full charge/discharge cycle. This is not practical in daily use in an EV for obvious reasons. The multi-cell pack (with cells in series) makes things even more complicated.

    Ever have a device report 100% SOC for seemingly forever, and then suddenly drop? Ever have a device say it has some battery left and then sudden die? That's because the SOC estimation is not correct or is crude (for example basically just mapping voltage to SOC, sometimes linearly).

    Here's some basic primer on battery SOC estimation:
    Li-Ion BMS - White Paper - Estimating the State Of Charge of Li-Ion batteries
    Measuring State-of-charge - Battery University
     
    • Informative x 1
  17. Mediocrates

    Mediocrates Member

    Joined:
    Apr 16, 2017
    Messages:
    63
    Location:
    San Diego, CA
    I understand that the battery charge state is based on electrical characteristic measurements and an attempt to correlate that to the available capacity. That's the same as it has been done for decades, depending on the battery chemistry and application. We agree on that (although I've never experienced the aberrant behavior you described in terms of wild charge state fluctuations).

    I contest the hypothesis that the "rated miles" is as (in)accurate as battery charge state, given they are in different temporal contexts and the former is an inferred prediction based on the latter as input to some function.
     
  18. stopcrazypp

    stopcrazypp Well-Known Member

    Joined:
    Dec 8, 2007
    Messages:
    8,776
    The rated miles was always just a direct wh/mi conversion from capacity to miles. It does not vary based on driving conditions. The only thing that changes the mapping (very slightly) is toggling to range mode. This has been a Tesla thing for a while (Tesla uses rated range as a substitute for a kWh number).

    @wk057 goes into detail here:
    Calculate usable battery capacity based on rated miles values
     
  19. whttiger25

    whttiger25 Member

    Joined:
    Jun 25, 2016
    Messages:
    397
    Location:
    Oakland, CA
    Driving history has nothing to do with rated range. Rated range is just a current estimate of kWh remaining in the battery multiplied by a constant which is unique to each battery and drivetrain combo.
     
    • Informative x 1

Share This Page