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Decreasing rated range.

Discussion in 'Model S: Battery & Charging' started by EMDoc, Jul 13, 2013.

  1. EMDoc

    EMDoc Member

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    Hi all - so my car has 4200 miles and I noticed that over the past week my rated range has dropped. Used to say 241-243 miles after a std charge. Now, it's showing 236. Is that degradation in play? Only 4200 miles...
     
  2. loganss

    loganss Spaceman

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    #2 loganss, Jul 13, 2013
    Last edited: Jul 13, 2013
    My standard range after 11,400 miles is now 236 miles. I wonder if some of that is due to a software update.

    My current firmware is 4.4
     
  3. Al Sherman

    Al Sherman It's about THIS car.

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    I'm guessing no. Are you on 4.5? It defaults to a lower percentage for a "standard" charge. I see around 227 vs. 242 when I leave the slider at the new default position.
     
  4. mckemie

    mckemie Member

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    #4 mckemie, Jul 13, 2013
    Last edited: Jul 13, 2013
    I'm at 8500 miles. My S's "rated range" seems to decrease with time elapsed after charge complete. If I drive immediately after charge complete, "rated range" is 242-244. After half a day, it may be as little as 235.

    With firmware 4.5, it may be restarting the charger as rated range declines. I have found it charging long after the initial charge should have completed. I haven't been willing to watch it close enough to be sure.
     
  5. aviators99

    aviators99 Model S - R140

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    1) Are you taking these readings as soon as it is done charging?
    2) How often have you charged at 80A since you got the car?

    I am trying to get to the bottom of this for myself, as well.
     
  6. jerry33

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

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    I'm seeing 240 instead of 242 at 6700 miles on 4.4. It's expected--based on the battery degradation graphs that other group members have kindly posted--that the battery capacity will go down quickly at first and then the rate will slow. It's been over 40 here, so I don't know how much of the reduction is real and how much is an artifact of the thermal maintenance. It wouldn't surprise me if the standard charge is reduced when it's hot to protect the battery although I don't know if that is actually the case. In any event, mine is not enough to worry about.
     
  7. aviators99

    aviators99 Model S - R140

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    Agreed that yours is what I would expect. My rated max range has gone from 273 to 258. I know of people with over 20,000 miles who are still up in the 270s. I do notice that the OP has twin chargers, and I have a hypothesis that 80A charging could be a factor. So far, it's not very scientific. Could also be something about Gray/Black ;-)
     
  8. jerry33

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

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    Or it could be that my display is showing 259 Wh/mile as an average for the 6700 miles.
     
  9. Treker56

    Treker56 Member

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    Any 60 kWh owners have metrics? For me after almost 3,000 miles our S60's rated range right after charge has decreased from 190 rated to 187 :/ Still on 4.4 as originally delivered.
     
  10. djp

    djp Roadster 2.0 VIN939

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    #10 djp, Jul 13, 2013
    Last edited: Jul 13, 2013
    I think there are too many variables to draw any conclusions about degradation yet. The displayed range after a charge can be affected by a lot of factors besides actual loss of capacity:

    - The reading can fluctuate at the end of a charge and take a while to settle in.

    - An out of balance pack will show a lower number, but it can be brought back up when the battery is balanced.

    - The algorithm needs to go through a full cycle of the battery (high SOC to low SOC) to recalibrate its estimate of capacity. On the Roadster this needs to be done on a single key turn.

    - Charging at lower amps or 120V can show a higher reading (possibly because of better balancing).

    - Ambient temperatures can vary the reading. I generally get higher readings in the summer on my Roadster than the winter.

    - Changes in the firmware can change the readings. For example the big drop with the lower "standard" charge in 4.5, but more subtle changes in capacity estimates can be made in each firmware release.

    What we really need is access to the CAC value (Calculated Amp hour Capacity) on the REST API to get a consistent reading of capacity.

    With less than a year on the Model Ss I think it's still to early to see degradation (except maybe on the extremely high mileage cars) and any differences in the estimates are probably noise from other factors.
     
  11. stsanford

    stsanford Member

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    I've got
    a 60 with just 1500 miles on it. It used to charge to 190, now it goes to 187, with 184 available by the time I unplug in the morning. I drive a mile or so and I'm in the 170s... Odd, and really not appreciated on a 60....
     
  12. Banahogg

    Banahogg Member

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    #12 Banahogg, Jul 13, 2013
    Last edited: Jul 13, 2013
    Using the REST API, I've been logging the state of the car every 10 minutes since I got it in February. To figure out how much it's charging to, I grabbed the first data point when the status went from charging to complete and where range mode was false.

    ratedmiles.png

    It was stable for a while, but has been going down significantly since about day 75. A linear fit on the data from [75,150] gives -0.0529667*day+192.8. If that trend continues, I'll be at 70% at the 3 year mark. Hopefully it does level out.

    You can't see it on this graph, but in the flat region, the percentage charge reported at completion slowly increased from 91 to 93, which may have been masking any degradation in that region. Hard to say with the data we can get access to...

    Edit: I should note I'm at about 5000 miles, though since the odometer isn't in the basic API (only streaming), I haven't been logging it.
     
  13. EMDoc

    EMDoc Member

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    Thank you so much for all the input. This community is fabulous. I'll try answer all the questions below. Btw, great analysis Banahogg..let's see what happens down the road.

    I have firmware 4.5 (ending in .54)

    I used to charge to "STD" prior to 4.5. With the 4.5, the slider is at the end of the "Daily Charge" so it does not enter the "Trip"

    I schedule charge at 12am...so perhaps the car sitting in the garage overnight lost some power. I drove at 9am this morning...sounds like it lost about 5-6miles of range sitting around for 7 hours while still plugged into the HPWC. That may make sense...but never noticed it before. Temp in garage is about 80 now.

    Is it true that 4.5 now has the daily STD charge that is lower than the previous STD charge? I thought they increased it to 90% (from 85%) with 4.5. I expected more mileage, not less.

    I also notice (as some have mentioned) that driving the first mile after a charge (whether immediately or delayed), the rating seems to drop by 5 miles immediately.

    Oh and I don't have the updated fuses for the HPWC, so I'm charging at 60A since I got the car in March.

    Thanks again!
     
  14. jerry33

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

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    4.4 standard charge is 93%, not 85%.
     
  15. steve841

    steve841 Active Member

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    I wonder if the reported drops have anything to do with the summer heating ....
     
  16. islandbayy

    islandbayy Active Member

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    Just hit 4,000 miles, standard charge still shows 190miles upon completion.
     
  17. EMDoc

    EMDoc Member

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    Thanks for the clarification Jerry. So, in 4.5 Standard charge is 85%? That would correlate with my mileage...
     
  18. EarlyAdopter

    EarlyAdopter Active Member

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    Banahogg,

    I've read several places that LiIon degradation is most pronounced in the first year, so if this indeed from degradation then you should expect it level out eventually.

    That said, I've had my car for 6 months now and still charge to the same 241 miles on a standard charge. Out of curiosity, any chance you might be able to add your firmware version history to that graph?
     
  19. EMDoc

    EMDoc Member

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    EarlyAdopter - what firmware version are you running?

     
  20. Banahogg

    Banahogg Member

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    I track my version as well, but it's not interesting enough to graph: 4.1 (1.19.42) from when I picked it up until 4/13 (day 59 on that graph) then 4.4 (1.31.11).
     

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