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Car doesn't charge to 90% any more

Discussion in 'Model S: Battery & Charging' started by tstafford, Sep 27, 2015.

  1. tstafford

    tstafford Member

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    Okay - so I'm sure I'm missing something very obvious.

    When I took delivery of my car six weeks ago it was set to charge to 90% which it did - this generated 227 miles rated range. This happened every night - sometimes it would show 226 but almost always 227.

    I had some minor work done to the car and the SC moved it to 100%. I failed to notice that, charged it fully and then moved it back to 90%. I have double checked the 90% setting in Visible Tesla.

    Now the car always charges to 89%. And it now shows 224 or 225 miles of rated range each morning.

    My OCD doesn't like this.

    What's up?
     
  2. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Did you install an upgrade? SOC measurement is never exact and has a tendency to change after an upgrade.
     
  3. ToddRLockwood

    ToddRLockwood Active Member

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    I believe Jerry has this right. The SOC algorithm has been updated periodically to make it smarter. In addition, these small variations can occur over time as the 7,000+ cells in the pack get slightly out of sync with one another. This can usually be corrected by allowing the pack to discharge to 10% once in a while, then recharge to 90%.
     
  4. idoco

    idoco Member

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    I don't think the sliders on the control screen or visible tesla are exact. When you returned it to "90%" after 100% you might think you have it set "exactly" where it was before, but really don't.

    If you want to check loss of capacity based on the rated miles display I would just keep track of 100% charged rated miles.
     
  5. muleferg

    muleferg Member

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    idoco say.
    you have it set "exactly" where it was before, but really don't.

    I vote yes.
     
  6. robert774

    robert774 Member

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    The same thing happened to me. I just set it to exactly 80% using the Tesla app, but as others said it doesn't really matter much. It's difficult to make precise settings from within the car's screen.
     
  7. FlasherZ

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

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    There's one way to set it exactly to 90%. Put it to 100%, drive and charge it about 3 different times, then the car will nag you to lower the limit when you get in, which it will set to 90% when you say "yes". As some have mentioned, it's easier to use the app, or capabilities in VisibleTesla.

    If you use TeslaMS, you can use teslacmd.js with -R to set 90%.
     
  8. Duma

    Duma Member

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    The comments about the imprecision of setting the charge level with the slider in the car are correct.

    A couple of other things to consider:
    • How much time elapsed between when the charge completed and you checked the SOC. If your 12V battery needed to be recharged due to the vampire load, this will reduce your SOC and could drop you 1%.
    • The car seems to run a re-estimating algorithm after charging. On my car, using VisibleTesla, I have seen the SOC increase from 65% to 66% about 2 hours +/- 0.5 hour after charging is complete. One morning I was surprised that the car had overcharged (with no slider fiddling involved) until I checked the data recorded by VisibleTesla. Since then I have seen this multiple times. I suppose the algorithm could also reduce the SOC but I don't know how to distinguish this from charging the 12V battery.

    A downside of the level of detail we have about the SOC and energy use is that it makes some of us a bit obsessive. So chill out. The fuel gauge precision on an ICE is 1/8 of a tank and in my experience (based on nominal capacity and the gallons pumped) even that isn't accurate.
     
  9. andrewket

    andrewket 2014 S P85DL, 2016 X P90DL (soon 100)

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    Remote S also lets you set it in 1% increments.
     
  10. mknox

    mknox Well-Known Member

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    ^^ This. My car will drop to 89% after sitting for about 2 hours. I try to time my charging so that it completes within an hour of when I plan to depart.
     
  11. LetsGoFast

    LetsGoFast Active Member

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    Actually, this happens to me too right now. Its not the setting -- I had it set to exactly 90% via Remote S, but it actually charges to 89%. I never do a range charge (once, I think) and I've been usually setting it to 80% when I'm around town. I assume it is some kind of calibration thing and it would probably reset if I did a full charge, but it doesn't quite bother me enough to try.
     
  12. tstafford

    tstafford Member

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    Oddly enough it charged to 90% today. I'm going to stop thinking about it.
     
  13. nwdiver

    nwdiver Active Member

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    Good plan :wink:

    Fretting over a few miles of range is just going to cause unnecessary stress... I wouldn't worry about anything less than ~10% of what's expected. More than that might warrant a call to Tesla to make sure you didn't have a module failure.

    Over 75k miles I've seen a lot of odd things with my battery;

    - Driving 10 miles at 100%, using 3kWh and STILL being at 100% SOC
    - Battery range goes UP after driving a few miles (battery warms)
    - Battery range DROPS ~5 miles after a software update
    - And... everyones favorite... clawing back range with multiple range charges... although I think this went away with the latest software update...
     

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