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Throttled vs. Non-Throttled Supercharging Comparison

Discussion in 'Model S: Battery & Charging' started by Naonak, Aug 13, 2017.

  1. Naonak

    Naonak Member

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    I have completed my trip. Here is the raw data:

    Pre / Post DCFC Throttle Data

    If anyone wants to collate and/or graph the data, that would be great. I'm not that great with spreadsheets to start with.

    Here are the take aways:

    • Yes, throttling increases your trip time.
    • Yes, it seems ~5 minutes is the increase from an absolute charge standpoint (with a caveat).
    • The amount of time to "continue your trip" has increased dramatically, but not due to throttling. It appears that Tesla has increased the buffer amount by approximately 10% since throttling was implemented, so a throttled car coupled with the new algorithm increases your "time to continue" by 10+ minutes per stop, giving the appearance of a much larger increase in charging time than actually exists. Tesla kind of shot themselves in the foot with this. Or at least the timing of the throttling discovery and the algorithm changes was an unfortunate coincidence.
    Armed with this new knowledge (for me), I feel a lot better about the throttling. Yes, it does increase my trip time, and yes it's annoying and yes I think Tesla really dropped the ball by doing this in stealth mode. My wifes P85 actually has better range than my P90, and hers has 100,000+ miles on it.

    All in all, the 90 packs are inferior to the 85 packs by almost every single measure (with the exception of the max amps I guess?). Usable energy in my 90 pack is actually less than in my wifes P85. My 90 pack has about 76 kWH of usable energy (I measured when the car was new), although that seems to have dropped and I just started a re-calibration to see how much actual usable energy I have now. My wifes 85 pack has closer to 80 kWH of usable energy, no apparent artificial throttling, and presumably a longer life in the presence of DCFC, even on an infrequent basis.

    If I were replacing my pack with a bought and paid for pack today, I'd get an 85 pack instead of a 90, assuming they could do the retrofit. Of course, I'd rather have a 100 pack, but that seems off the table for the immediate future.
     
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  2. apacheguy

    apacheguy S Sig #255

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    Tesla may be returning to the older cell chemistry in part because of these issues.
     
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  3. brianman

    brianman Burrito Founder

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    @Naonak
    Thanks for sharing your data.
     
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  4. pilotSteve

    pilotSteve Member

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    I *did*replace my 2012 S85 with a late 2016 S90D. I’ve experienced supercharger throttling to a similar degree. Range so far (12k) miles hasn’t decreased but you have me concerned...
     
  5. spottyq

    spottyq Member

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    Thanks for taking the time to collect and share this data.
     
  6. tnt1971

    tnt1971 Member

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    I got one of the last 85s. They called me several times trying to get me to upgrade for $3,000. Glad I did not.
     
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  7. Max*

    Max* Not Banned

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    This buffer has been all over the place, I think this change is not due to the throttling but just something Tesla messes with. This time it might have timed it with the throttling. I usually ignore that number, and chose my own safe buffer and drive.


    I've seen it require 7% (red to yellow buffer), either (10% or 15%) and 20% (green to yellow buffer). <-- buffer to arrive at your destination with before it says "enough charge to continue trip".

    It started high, then they lowered it as low as 7%, then brought it back up. I want to say now it's 20%, but I could be remembering wrong.
     
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  8. Naonak

    Naonak Member

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    I don't think it was changed due to the throttling. I was just saying it was a poorly timed coincidence.

    Yes, at least for me, it's now at 20% from the previous 10% a year ago. The 10% was optimistic and would never have gotten me to my destination. I always buffered to at least 15% if not 20%.
     
  9. silverp85+

    silverp85+ Member

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    The P85Ds with range upgrade to P90D has the battery chemistry in question or the P90Ds that were born as P90D?

    The throttling wouldn't bother me much, I'm just curious.

    Thanks
     
  10. apacheguy

    apacheguy S Sig #255

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    Can't say for sure, but yes I suspect anything carrying a 90 kWh is susceptible.
     
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  11. SeminoleFSU

    SeminoleFSU Voluntaryist

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    How sure are we that the 100kWh pack doesn't use the 90's chemistry? Has this been actually verified?
     
  12. MP3Mike

    MP3Mike Active Member

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    We aren't at all as it does.
     
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  13. FlyingCookie

    FlyingCookie Member

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    I’ve seen the buffer all over the place in the last week, having driven about 4000 miles. Sometimes it’ll buffer to 10% other times it wants 25%. I just leave at 10% and usually arrive around 7%. (Lead foot) This can vary from “Enough energy to continue your trip” to “15 minutes remaining.”

    So have we determined that only the newer chemistry batteries are susceptible to throttling? If so, I’m suddenly that much more glad I got a P85 instead of a 90... I’ve been getting amazing range out of my preowned P85, and it looks like in 50k miles it has lost a whopping 1-2 miles of rated range... And obviously with the kind of mileage I’m putting on the car, I’m stopping at superchargers at least 8 times a week. (4 stops on Monday and Friday and usually a quick stop mid-week to get through the week, though I have found some nice places in Houston with good food and L2 chargers)

    I can also consistently hit 275wh/mile at 75MPH. (Though I am running tire pressure a touch high when cold, so that may have an impact) This makes road trips in the P85 an awesome breeze.
     
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  14. SeminoleFSU

    SeminoleFSU Voluntaryist

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    I will be honest I have seen slower supercharging speeds and a faster taper across the board in road trips I've done recently (one from Atlanta to Little Rock AR and back and the other from Atlanta to Birmingham and back)
    It seems like the car tapers much more aggressively. Many times it seemed to ramp up to 100+kW only to fall very quickly to 70-ish. At one point I was getting 84kW at 32% during one session. So it's hard to tell... It seemed to be dependent on the SpC location... I was doing my best to stay off pedestals paired with other cars charging... IIRC this is done by hitting 1B if someone is on 1A. The alpha part of the label is what signifies they're paired, not the number. Please correct me if I'm wrong!
     
  15. MP3Mike

    MP3Mike Active Member

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    The number signifies what charger stack the pedestal is connected to. So 1A and 1B are paired and share the same Supercharger stack/cabinet.

    You want to be hooked up to a stall where you are the only one on that number.
     
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  16. RyanT

    RyanT Member

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    Are you saying the 85s don't throttle? I have a 85 with 60K on it. For awhile now the highest supercharger speed I've seen is 90kW. I wonder if it's because I have a loaner pack. I've had the loaner pack for about a year! I wonder if I'll ever get mine back.
     

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  17. MP3Mike

    MP3Mike Active Member

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    We haven't seen any evidence that 85kWh packs ever throttle. However, the original 85kWh packs, the A revision ones, are limited to a maximum charge rate of 90kW.
     
  18. RyanT

    RyanT Member

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    Is there a good way to check my loaner pack letter?
     
  19. Galve2000

    Galve2000 Member

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    My recent SuperCharging experiences mirror exactly this. the car will ramp up to 114/115 kW for a few sends and over the next 5-4 minutes slowly drop down to the mid 70s (kW)

    admittedly i'm starting with 45 or 50 rated miles in the pack, so its not exactly empty.. but its nowhere near full and I expected to get above 90 kW for far longer.

    still i'm adding 130 miles in 25 minutes which is not bad.
     
  20. mspohr

    mspohr Active Member

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    I'm not sure this is correct.
    I have an S85D and it always has throttled.
    If the charge state is low it will start out at 120kW and then decrease as the pack gains charge.
    Lately is seems to be throttling earlier with a longer slow taper at the end if I try to go to 100%.
     
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