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Using SMT "nominal full pack" to figure degradation?

Discussion in 'Model S' started by Alset2, Oct 18, 2020 at 7:09 AM.

  1. Alset2

    Alset2 Member

    Joined:
    Feb 20, 2020
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    Location:
    ocala
    Sorry if this has been covered, I just want to make sure I understand .
    My NOM FULL PACK is currently 92.7 . It has dropped from 95.1% on my 1st scan in May of 2020.

    To figure degradation, do I use 7.3% or do I take the 5% buffer out and call it 2.3% degradation ?
    Since my 1st scan had it inside the 5% I am afraid the answer is 7.3% degradation ?

    Also at 93.7 % SOC (today) my battery voltage is only at 395 volts , does that seem right ?

    Sorry , I know there is a lot of threads about this and I have read a lot! This is just such a great place for getting direct answers so thanks in advance.

    Screenshot_20201018-094550.jpg
     
  2. Alset2

    Alset2 Member

    Joined:
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    Location:
    ocala
    Sorry , I can not edit my orig post , but I meant to type "KWH" not percentage in the second sentence ..

    "My NOM FULL PACK is currently 92.7 KWH . It has dropped from 95.1 KWH on my 1st scan in May of 2020"

    I am surprised no one has answered though ...maybe its because I answered my own question!! lol

    Just like confirmation on which it is- 7% degradation by KWH with SMT or only about 3% based on Teslafi range .
    Of course I did get an update last month which increased my range calculations up almost 20 miles so I think that throws Tesalfi off since it is based on "starting" range reported.

    Anyway, any input would be welcome to help me clarify what I should be considering my reported degradation to be

    thanks again
     
  3. serendipitous

    serendipitous Member

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    Location:
    Maryland, USA
    You've got this mythical 100 number in your head that isn't real. The current batteries (including yours) are not a 100kWh pack. They seemed to start around 98kWh Nominal Full Pack, of which 93kWh was usable. Older ones had ~103 of which 4 was buffer. So if you want to be pessimistic, you probably have 92.7 / 98 = 94.6% of the original capacity, or ~5.4% degradation. Since your first actual measurement, you're at 92.7 / 95.1 = 97.5%, or only 2.5% degradation.

    However, I would wager money that your nominal full pack is not ACTUALLY 92.7. If you run it down to 10%, and let it sit/sleep. and then charge it slowly (not at a supercharger) to 95% or even 100%, and then let it fall asleep, you'll probably return to a reading of 95kWh.

    Mine fluctuates between 93.0 and 95.5 - after any long trip, when I give the battery a chance to go through the full range and recalibrate, it goes back into the mid-95s.
     
    • Like x 1
  4. Alset2

    Alset2 Member

    Joined:
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    Location:
    ocala
    Thank you very much.
    You are right with my 100 number.
    I appreciate your time and info.
     

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