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Will the 60kWh have a longer Batt Pack life?

Discussion in 'Model S: Battery & Charging' started by mdevp, Jun 11, 2016.

  1. mdevp

    mdevp Member

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    If there is 75kWh being used over the lifetime of the pack would it theoretically have less degradation %wise than a 75/85/90kWh pack?
     
  2. techmaven

    techmaven Active Member

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    One of the big issues to determine the actual answer to your question is that we don't actually know the State of Charge (SoC) range that is programmed into the software limiter. That determines the voltage range of the cells and that is one of the determinants of degradation.
     
  3. mdevp

    mdevp Member

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    I just figured that the 'extra' 15kW would be charged/cycled just as much as the rest, resulting in less cycling overall per battery over say 10yrs. Shouldn't this pack have less degradation then the original 60kW packs? Sounds logical, but I'm far from knowledgeable in this area.
     
  4. techmaven

    techmaven Active Member

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    In general, yes. But only if you actually use the pack at a wider SoC if you had the rest of the pack unlocked. For example, it is possible that you buy the 60 and use it exactly the same way, with the exact same SoC range as if it was the unlocked 75. Then the degradation is exactly the same. But of course, you save $$$. But a few times you use the full 75, but you really don't do it all the time, the difference in degradation may be difficult to measure.

    Depending on the SoC range, it is possible to abuse your particular 60 kWh pack in a way that would be worse than the average use of a 75 kWh pack. But we're kind of into the weeds there.
     
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  5. DOBYUSA

    DOBYUSA Member

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    if you buy software-limited 60kWh pack... its 75kWh battery ! ! ! not a 60...
    just software-limited to 60 ! ! !
    that means if you buy a 75kWh battery ...Tesla recommend to charge its to 90% for daily use, and only if you need its ,it's OK to go above 90 % ..
    That mean if you buy software-limited 60kWh pack... when you charge its... if you charge its to 100 % ... its is not 100 % of the capacity on the battery ! ! !
     
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  6. techmaven

    techmaven Active Member

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    Quite possibly, but we don't know the programmed SoC range.
     
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  7. DOBYUSA

    DOBYUSA Member

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    just need to see if anyone got one of them ...and ask him to see when he charge its at the supercharger what is the voltage on the right on the touchscreen when he charge at 90 or 100 %
    in general Tesla's battery is 400 V... when is almost empty is about 350 V...
    you can over charge its above 400,but I try not to go above 404 V myself ... because its 400 V battery ...
    Any AC equipment can tolerate no more of + - 10 to 13 % of its rated voltage ... or 40-50 Volts in this case
    so if 100% charge of software-limited 60kWh pack is below 400 V... its not charged to 100 %
    but if is... then Tesla is making that car to charge to 100 %... that is above of recommended 90...
    What side of reserved voltage of the battery they limit ? the bottom or the top ? :)
    You can't limit its capacity ,but the voltage when you charge ...
     
  8. supratachophobia

    supratachophobia Active Member

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    I think this is accurate. The only downside is explaining to customers that if they opt for the software unlock at 100k miles, they might only have an extra 8kw instead of the expected 15kw.
     
  9. Brass Guy

    Brass Guy Member

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    (Also not an expert.) Let's assume for now that a 60 limits the top end of charging. If your driving results in going below 10% more often because you got a 60, that's probably worse than charging over 90% occasionally. If however you max charge the 60 (which is 80% of the 75) and don't go below 20%, then yes you'd get the same degradation as a 75 staying between 80% and 20%. I think it's more likely that on road trips you'd end up driving into the bottom of the pack more often than if you had a 75 which is (supposedly) worse than charging higher.
     
  10. mdevp

    mdevp Member

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    I agree, given most people charge to 90% most of the time, that'd be 80% SOC used most of the time used everyday. If it's a typical ~60 mile commute like I have, I'd figure over the pack's lifetime=less degradation. Remains to be see how much of a difference, if significant at all.
     
  11. supratachophobia

    supratachophobia Active Member

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    Everyone is seeming to forget that Tesla will choose the best option that will give them the least amount of battery degradation for CPO resale later. Mark my words, the "70kw" battery will make a comeback on these 60kw that are traded back in.
     
  12. Snerruc

    Snerruc Member

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    On another thread a Tesla employee said that the 60 will have max voltage restricted so that all cells are used charged to approx 80%. He didn't know if the charging software would be written to give a charge curve mimicing an actual full charge.
     
  13. DOBYUSA

    DOBYUSA Member

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    in other words... that is backing my story ... software-limited 60kWh pack when is charged to 100 % is not a 100 %...
    because is 75kWh battery,not 60...
    so if anybody buy its... just need to charge it to 100% instate of upgrade to 75 kWh and charge its to only 90 % after that...
    ...needed only somebody to prove its white actual voltage numbers ....
     
  14. DOBYUSA

    DOBYUSA Member

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    Tesla need to sale 100,000 cars by the end of the year... Now is June... the cost of the battery is down ,but they can't afford to go down on the prices for same model because people who buy 75kWh battery model will get mad ...
    you can buy 75kWh car and charge its to 90% ...
    Or you can buy software-limited 60kWh ... and charge it to 100 % for less money ...
    Its like they reduced the price and not made anybody mad :)
     
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  15. S4WRXTTCS

    S4WRXTTCS Active Member

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    In most cases I don't think you'd detect a measurable difference.

    The 75 owner likely will only charge to 80 or 90% which gives a pretty good life longevity. As long as they don't make a habit of low states of charge.

    The 60 owner will likely charge to 100% (cause its 80% of the actual battery).

    So what's really funny is in 90% of use cases there is absolutely no difference with it being a 60 versus a 75. The only difference is on trips where the 75 owner can charge above 80% range all the way to 100%. So that gives them more buffer in those cases, and as a 70 owner I'm definitely familiar with times where I wish I had just a bit more buffer.

    Really when it comes down it there is no knocking the choice to get a 60, 75, or 90. They all have there strong points.

    For me I'm going to wait to upgrade until they come out with a 120kw. That way it allows me to avoid the supercharger on common trips.
     
  16. mdevp

    mdevp Member

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    On a side note, if the S60 is the same production price of an S75, that will mean the S60's profit margin will be ~12% less, right?
     
  17. S4WRXTTCS

    S4WRXTTCS Active Member

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    That's correct, but keep in mind battery cost have been falling. So while it is ~12% less it's likely fairly close to some previous profit margin.
     
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  18. Derek Kessler

    Derek Kessler Member

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    Yes, but Tesla would have only made this decision if after running the numbers of expected upgrades that they would come out even or ahead in the long run — which means the 75kWh packs are probably on-par cost-wise with the older 70kWh packs (if not somehow cheaper thanks to the magic of economies of scale).
     
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