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100% charge vs. Supercharge?

Discussion in 'Model S: Battery & Charging' started by Kgdietz, May 10, 2017.

  1. Kgdietz

    Kgdietz Member

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    In light of the new info about potential limited DC fast charging over the lifetime of my car, I'm wondering if I should change my thinking about 100% charges. Usually when I leave on a trip that will involve a Supercharge session, I only make sure I have enough to make it to the SC, plus a margin. In my situation, almost any trip I could take has an SC within about 150 miles from home so I just make one of those my first stop and I rarely charge beyond the daily limit.

    Now, If more supercharging is going to maybe limit me in the future, maybe I should charge to 100% before leaving home so I supercharge less at my first stop. Or, will it come out in the future that my car will be limited in some way because I "charged to greater than 90% more than a specified number of times." (paraphrasing the Tesla letter about limiting supercharge rates).

    I know, some of you will tell me some version of "you can charge to 100% any time you want, just don't leave it there for a long period" or "What really matters is the temperature when it is at 100%, if it's below x degrees, you have nothing to worry about". But are you really so sure of that? What if a new little nugget drops about 100% charges? I now know that there is a "price" to supercharging, I just want to know how that compares to the "price" for a 100% charge.

    It's a hypothetical, folks. Just puttin' it out there.

    Ken
    '15 Model S 70D
     
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  2. jbcarioca

    jbcarioca Active Member

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    It is really humorous to find so many people who have a nearly religious fervor about this issue.

    I think there are about three valid generalizations:
    1. In theory, li-ion and most other chemistries are negatively affected by overcharging;
    2. The Tesla BMS acts very, very effectively to minimize the negative consequence of high SOC by active thermal management, tapering (with schedules that vary by specific chemistry, design and other factors (shorthand: battery pack version)
    3. In general is is preferable to avoid charging above 90% as a rule of thumb even though many people do so with no apparent ill effect.

    Back to #2 for a moment. The recent furor about excessive DC charging as a negative factor, and Tesla reducing available rate of charge is vastly overblown in practice because it is a fairly modest reduction to begin with and because one must really, really use almost only DC charging for a long time to trigger the response. FWIW, all the available evidence suggests the only battery packs for which this happens may be the early packs is partial silicon anodes, such as yours. "all the evidence" is not much however, so very few will be affected.

    Your described behavior is spot on with Tesla recommendations. I suggest you stop worrying about it and enjoy your drives. With your pack, anyway, unless you get the OTA upgrade your 100% is quite a bit less than that anyway, so go to 100% whenever you feel like it.
     
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  3. Max*

    Max* Not Banned

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    I charge to 100% before every trip. It saves times on the first supercharger stop. I'd rather let the car charge at home, than waiting at the SpC.
     
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  4. Chopr147

    Chopr147 Active Member

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    I am in the jbcarioca camp. NOT going to worry about it. Of course my usage is "maybe" 2 supercharges a month.
     
  5. TexasEV

    TexasEV Well-Known Member

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    If you're going on a trip, do what saves you time, which is charging to 100% at home so your first stop is shorter. It's not like you're doing this every day. Or you could keep doing what you're doing if you're happier that way. The car isn't going to care either way. You usage pattern clearly isn't in the 99th percentile of DC charging, right? Stop worrying and just enjoy your car.
     
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  6. tpham07

    tpham07 Member

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    I dont forsee myself ever fast-charging my car 300+ times, and i plan on owning the car for 7+ years. I see maybe 20 supercharges a year tops.

    So no, this is not a concern for me.
     
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  7. oktane

    oktane Active Member

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    If you charge repeatedly to 100% Tesla may electronically limit you to 90% in the future permanently. I charged to 100% 3 times in a row and got some message warning me not to do it again or else.

    I am afraid that if I keep doing it some Trojan horse code or counter flag will restrict my charging.

    Am I being paranoid?! I don't want my P100DL to become a P90D.
     
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  8. Max*

    Max* Not Banned

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    Can't tell if serious or trolling...

    If you're serious, re-read the message. It's a recommendation after 3 days set to 100%, asking if you're sure you need to charge to 100% because charging to 100% will degrade range longterm.
     
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  9. oktane

    oktane Active Member

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    Both. What I'm saying is not unrealistic. I am worried that continued 100% charging will have consequences enforced by Tesla.
     
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  10. Galve2000

    Galve2000 Member

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    One of my biggest questions from the ever-growing thread on possible throttling after too much DC charging was exactly this:

    What's worse for the battery? Too much SCing vs charging to 100% (or over 90%) too often?

    For now I am going to assume that charging to ore than 90% is the more detrimental of the two b/c Tesla has actively discouraged this but on its website and in the car itself. I left my battery 85 kW battery range to 95% for a few days but never charged to more than 80% or 90% and the car software kept reminding me that it is better "keep the battery at 90%" (i'm paraphrasing) even tho I didn't exceed the 90% limit in practice at all during this time.

    As an aside when purchased my car it was delivered to me with 95% charge in the battery b/c i made it a point to tell everyone that I was an apartment dweller that hadn't figured out where I was going to charge my Model S.

    I have not weighed in on the to much DC charging is bad thread even tho I have a lot to say on the topic.

    briefly:

    it is my feeling that the algorithm that Tesla is using to count DC fast charges is doing a sloppy job. I can not imagine how charging at 45 or 50 kW daily (or more than just occasionally) is THAT much worse than some of us who charge at 22kW daily of "dual chargers" daily (full disclosure, my 85D only has 1 onboard charger currently.)

    I think the algorithm never thought it would run into someone who had done 250 DC changes (albeit much slower rate/lower powered than superchargers) in so few miles (only 30,000) and "freaked out" and restricted his car. IMO this restriction should be removed from this person's car, unless of course there really is a detriment and Tesla needs to disclose same.

    but back to the topic at hand:

    I wish Tesla would weigh in officially.
     
  11. abasile

    abasile Working on EVBuySell

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    I feel quite confident that Tesla won't ever stop you from charging to 100% on a daily basis, as the EPA range ratings are predicated on being able to charge to 100%. There is, on the other hand, a rational basis for throttling Supercharging on batteries that are cold and/or degraded (though I'm not in favor of having an overly simplistic "counter").
     
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  12. TexasEV

    TexasEV Well-Known Member

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    Since you asked, yes, you are being paranoid. Or just trying to start a controversy where none exists. The warning is just a reminder, as some people who set charge level at 100% for a trip forget to set it back to a level for daily use. It's so you don't keep charging to 100% when you don't want/need to do so. Chill.
     
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  13. AnxietyRanger

    AnxietyRanger Well-Known Member

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    I doubt you can assume much anything here.

    The 90% is a no-brainer for Tesla, there is no inherent downside for them to ask people to charge to 90% most of the time. So they ask. Why 90% and not 50-80% as those would be even better from the science perspective? Because 50-80% start approaching an issue for adoption... 90%, not so much. People can get that. Close enough to the top.

    However, warning people to stay away from Superchargers would be a serious issue for Tesla. Hence JonMc specifically did the opposite in the message about the ~5 minute Supercharging delay (8% delay) due to some amount of DC charging in the past. Even though he acknowledged an issue from frequent Supercharging, he actually then referred to Tesla continuing to encourage people to Supercharge more.

    It is a tricky thing to balance, for Tesla, the question of battery recommendations that work and keeping those recommendations on such a level that they are not obstacles to adoption. There are science reasons and then there are business reasons. Just being real here.

    I have no idea which is worse for the battery 100% or DC charging (my personal recommendation is avoid both if not necessary), but I do know we can't really tell that from Tesla's reaction because of the conflict of interest either.
     
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  14. oktane

    oktane Active Member

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    I really like being charged to 100% though.....makes the car much more enjoyable. The acceleration is noticeably different between 75% and 100% SoC. It's the difference between a car that does 0-60 in 2.8 seconds vs. 3.5 seconds, which is substantial!

    I hope you're right about Tesla's legal obstacles to limiting 100% charging based on use to avoid warranty claims. They've done it before for supercharging rates and for peak power delivered, nothing other than lawyers will stop them from doing this too - especially if nag screens are popping up and no doubt sending messages back to the mothership.
     
  15. SageBrush

    SageBrush Active Member

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    #15 SageBrush, May 10, 2017
    Last edited: May 10, 2017
    OP: If I am not mistaken your battery is 75 kWh, software limited to 70 kWh. So charging to 70 kwh is 93.3% of the nominal "full" capacity of these cells. You can charge up to ~ 90% every day of the week and be quite close to Tesla's best practices guidelines.

    As for your trips, unless they are frequent (multiple times a week ?), you are no where near the group that Tesla is targeting for ~ 5 minute longer SuperCharger sessions.

    Breathe easy
     
  16. Kgdietz

    Kgdietz Member

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    Actually I'm a "true" 70D, build in 10/2015. My point was I am indifferent as to 100% AC charge before the trip, or an extra 10% (24 miles in my case) of supercharging during the trip. I wondered which was best overall. Completely understanding there is probably very little difference.

    Ken
     

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