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Worst case scenario, maximum time at Supercharger

Discussion in 'Model S: Battery & Charging' started by LetsGoFast, Mar 25, 2015.

  1. LetsGoFast

    LetsGoFast Active Member

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    Assuming I can be alone (not sharing a paired charger) and the supercharger is operating normally (not limited to 60kw), what would be the worst case scenario for getting a full range charge from a SOC near 0%? I've searched a lot of threads and have seen some data that suggest that going to 100% from 0% might be something like 110 minutes, but then I've seen other numbers that look like the max should be more like 90 minutes. The critical factor seems to be going from 90% to 100% which is reportedly very slow.

    I ask in the name of science, as I'm planning a drag race test and trying to figure out the most time efficient way to go about it.
     
  2. JohnQ

    JohnQ Active Member

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    Here's Tesla's answer, though I believe it's from 10% initial point. Assuming 10% equals about 7.5 kWh and a 120kW charge rate that's an additional 4 minutes to capture that energy. So, according to Tesla, about 80 minutes.

    I can't speak from experience as I'm limited to 90 kW charging in an A battery. Perhaps others can comment based on empirical evidence.

    Supercharge screenshot.jpg
     
  3. wraithnot

    wraithnot Model S VIN #5785

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    #3 wraithnot, Mar 25, 2015
    Last edited: Mar 25, 2015
    I've logged data for several complete supercharges from my car (S85 with a "B" battery pack) and I can certainly tell you what I observed (with the caveat that a P85D might behave differently).

    The two instances where I have the best data were both at the Mt. Shasta supercharger. The first time, I started with 47.8 rated miles of range (18% state of charger), and 111 kW. The state of charge hit 99% (256 rated miles) at 91 minutes, hit 100% (258 rated miles) at 111 minutes and stayed at 100% until the car stopped charging at 120 minutes. The second time, I started at 25 miles of range (9% state of charge) and 108 kW. The car reached 18% state of charge in 4 minutes, hit 99% state of charge at 77 minutes, hit 100% at 81 minutes and stayed at 100% until the car stopped charging at 127 minutes. I'm not sure exactly why the car continues to charge when it reports 100% state of charge- perhaps it's balancing the battery pack during this period. Anyway, getting those last few miles of range can take as long as getting the first 200. I tried to boil this down to the most relevant numbers, but I can try and post the full dataset (sampled every minute) if you'd like.
     
  4. David99

    David99 Active Member

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    My experience is about 100 minutes. Tesla's graph is too optimistic and not real world data. The best I got was 150 rated miles in 30 min (starting from almost zero). From there it slows down significantly.
     
  5. Brass Guy

    Brass Guy Member

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    I've had similar experiences. The last few percent are slower than you can get on a NEMA 14-50. I suggest not bothering to get that last bit at a supercharger. If you really need that last mile of range, just drive 2mph slower, it'll take much less time. If you want to balance the pack, do it at home sometime while you sleep.
     
  6. techmaven

    techmaven Active Member

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    The issue is that last little bit can really take a very long time. There's a point where it's crawling along for the last few hundreds of watts that probably not worth waiting around for. There are environmental factors and your pack is likely balancing at that point, so it becomes extremely variable too.
     
  7. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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  8. billarnett

    billarnett Member

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    What does "balancing the pack" mean? How do I do it? Should I do it often? What happens if I never do it? Do I get better performance or range with a "balanced" pack?
     
  9. TexasEV

    TexasEV Active Member

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    Keep you car plugged in when you can, let the battery management system manage the battery, and don't think about it.
     
  10. Zextraterrestrial

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    this is very true!

    I'd say 85min 0 -100% if temps are mild but maybe 90 or 100 depending on balance condition. It seems like the SCs are pushing more power at higher levels than they were in early 2013. I remember being under 10 kW at 98% and thinking there was no point to ever go beyond 98% at an SC, not anymore. last fall I charged 9-261 rated at Grants Pass in 80min and was still at a 9kW charge rate at 100%, this weekend at petaluma was the same
     
  11. billarnett

    billarnett Member

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    Sure, that's what I do. But I would still like to understand what's going on in there... :)
     
  12. NOLA_Mike

    NOLA_Mike Active Member

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    Me too. At first look it would seem like it's wasting energy since the rated miles don't go up anymore while it's sitting there sucking up 6 or 7 kW. But I have found that if I let it complete that little exercise of "balancing" or whatever it is doing that when I drive off I can go 3 or 4 miles before the rated miles start counting down - so it does seem to be adding miles/capacity to the pack.
     
  13. David99

    David99 Active Member

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    Lithium batteries are very "sensitive" when it comes to charging them 100%. You have to be very careful not to overcharge them as it would damage them. The voltage of a battery depends on the state of charge. It's high when the battery is full and low when the battery is empty. Think about it this way: the bigger the difference of the battery voltage at any given time and the maximum voltage when it's full determines how much power you can give it to charge. In the beginning the difference is large, so you can charge fast (with high power). The fuller it gets, the smaller the voltage difference to the maximum is, the slower you have to charge (less power). At the very end, the charge power is reduced gradually to make sure the maximum voltage is never exceeded. At this point the voltage doesn't increase any more, but there is a smaller and smaller current still going in the battery to completely charge it. Almost all manufacturer have set their battery indicator to show 100% when the maximum voltage is reached, even though there is still a little bit of power going into the battery.
     
  14. brianman

    brianman Burrito Founder

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    Specific, direct answers to your question haven't been offered by Tesla. There's been somewhat extensive research on the forum into the topic but we haven't (to my recollection) reached consensus on very specific rules of thumb.

    That said, generally good advice:
    - - - Updated - - -

    Dumbing it down for entertainment purposes only.

    Imagine you're playing Tetris with a 20 row board. Jagged pieces drop down and stack or slide into place next to each other. As you complete full rows, they vanish ("magic!") as the pieces straddling them change shape, the pieces fully contained vanish, and the pieces above them slide downward.

    [1] Simplified telemetry might report how many rows are occupied, but not tell you how many empty columns there are in each row.

    [2] Fancier telemetry might tell you how many holes are present within the occupied rows.

    [3] Even fancier telemetry might tell you the exact configuration (like what you see when you play the game).


    "TMC research" has been trying to learn from [1] because Tesla hasn't made [2] or [3] available to us. Perhaps someday they might. If it's important to you, give Tesla feedback ([email protected] or in response to surveys from the service center after you visit) so that their "human telemetry" will bubble up such concerns as "important" to more than zero owners. :)
     
  15. ljwobker

    ljwobker Geek.

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    I did a bunch of math and data collection on my cross-country trip. The VERY short answer is "look here" :
    Tesla SuperCharge timer - Google Sheets

    To use, just subtract the starting charge from the finishing charge.... so if you start at zero and need to go to 100%, you need 75 minutes.

    There might be a couple of these that are off by a minute or two, but I have a metric poop-ton of data points from my cross country trip so the accuracy is as high as I can realistically make it (at least for my car, which is an April 2014 S85).

    There's a lot more data in these two threads, hopefully they're useful to others:
    supercharge data from cross-country road trip

    Model S charge curve as a .CSV or easily readable graph?
     
  16. Zextraterrestrial

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    I did a couple of 0 to 100% charges while I was in Oregon last weekend at the SSCC Enduro,
    temp ~60F started close to 120 kW, saw 118 at 2% - 1110kW @24%

    on the way-
    80 min 0-99% and still charging (253 mi)
    way back
    78 min from 0-100% still at 12kW charging (254 rm) - was at 100% after 74 min but still charging at 16kW
     
  17. davesm

    davesm Member

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    Does anyone have similar data for a 70D?? I couldn't find it in any of the threads...
    I assume that the 0-99% charge time must be less than that of the 85D, but have no idea how much less, and how the rate of charge will vary over time...
     

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