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Supercharging: multiple charging speed restriction?

Discussion in 'Model S: Battery & Charging' started by Couscous19, Jul 21, 2018.

  1. Couscous19

    Couscous19 Member

    Joined:
    Jul 13, 2017
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    Location:
    London
    Today I had a long drive across the UK, twice stopping at superchargers. The charging rate during the 2nd time was much lower than I expected and the rate did not change throughout the entirety of the session. It reminded me of the new Leaf limiting charge speed during a 2nd rapid charge of the day:

    Nissan 'misled' buyers of electric cars

    Has anybody experienced / heard of similar issues with Teslas?

    Some background info:
    - Overnight charged to 83%.
    - Drove quite a lot during the day. Supercharged at 11:50 a.m. from 70% to 90%. Charging speed was in line with expectations.
    - Plenty more driving, mainly on motorways. Stopped for an hour or so twice.
    - Supercharged at 5:30 p.m. at 51%.
    - This second occasion charge rates were circa 45kW the whole time; lower than expected at this SoC. Charged for about 20 minutes to 70%.
    - British heatwave; ambient temperature was between 22 and 26 degrees Celsius throughout the day.
     
  2. gaswalla

    gaswalla P4201/85/airsusp/pano/19i

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    Sounds like your battery was quite hot for a number of reasons. The lower rate in that case would be to protect the battery
     
  3. kiwi

    kiwi Member

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    That does seem strange.
    You supercharged just before 12. I’m going to guess it took ½ an hour.
    So you drove from 12:30 to 5:30 with 2 x 1 hour breaks.
    So that’s about 3 hours driving with long breaks.

    It seems unusual that the cars’ TMS couldn’t keep up.
    22-26 sounds balmy for the UK, but its really not that warm.
    I remember reading that 40 degrees give the most range, so that’s likely the temperature where the TMS is working the least.

    Personally I’ve driven multiple (3) 2-3 hour stretches with supercharging in between, during an NZ summer (similar temps) and had no reduction in charging. Perhaps you have a P model with launching everywhere :)

    Having said all that, as @gaswalla says - its obviously slowed down to protect the battery.
     
  4. widodh

    widodh Model S 85kWh

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    Did you share a SuperCharger stall with another car, the famous A and B pairing maybe? That can lower the charger rate.
     
  5. Couscous19

    Couscous19 Member

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    Silly me, should have mentioned that I was not sharing the stall; only 3 cars on a 10 bay supercharger and we were all spread out.

    To reply to my Kiwi friend, I just have a plain 85 kWh model S so sadly no firing the car out of a bullet chamber. I even have a small dog so spent the whole day in chill mode, reducing the intensity of the discharge. I might email the supercharger support address to see if they have any ideas.

    Thanks all for your thoughts.
     
  6. Lanber

    Lanber Member

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    Norway
    I think the comment about hot battery is spot on, and maybe you can sort it yourself:

    If you have the car in "range mode ON" the battery will have a higher target temperature for operating and go straight into active cooling when you hit a supercharger. Think the passive target is raised from 35 to 42C.
    Another downside is reduced AC output.

    Really, range mode ON is useless. I never use it unless in winter, where it will minimize the energy wasted in heating the battery.
     
    • Like x 1
  7. Couscous19

    Couscous19 Member

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    Oohh so as in right before you plug in to the supercharged turn range mode to ON so it doesn’t restrict the charge rate as much on a hot day?
     
  8. ewoodrick

    ewoodrick Active Member

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    Sound like s destination charge rate. Could have been a supercharger issue. Did you try moving?
     
  9. Rocky_H

    Rocky_H Active Member

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    Yes, from the past few summers in the U.S., there have been some Supercharger handles that get very hot from a combination of heavy use and very hot outside temperatures. The heavy use does two things. It seems there are some physical connection points in that cable/handle interface that get a little worn or slightly damaged from a lot of pulling and bending over time. And very heavy constant use, is lots of high current running through it, which makes it very hot. So sometimes some of the Supercharger stalls detect this extra high heat condition and reduce their power level down to something like 40-60kW to keep cooler. When Tesla is notified about these, they will have a tech replace the cable, and it fixes that.

    Here is a comment with links to a couple of other threads about this:
    charging slow at Superchargers

    You mentioned 22 to 26 degrees Celsius, which isn't very warm--only up to mid to upper 70's Fahrenheit. This kind of phenomenon shows up in the U.S. in places where it's getting up to 90 to 100+ degrees Fahrenheit, because it's hard for them to get a chance to cool down. I was in Ellensburg Washington last weekend, and it was about 101 Fahrenheit outside (about 38 degrees Celsius), and my charging rate was stuck at about 41kW, even though my state of charge was only about 42%. That's a pretty heavily used station, so the combination of use + heat is hard on that issue. But my previous stop at Kennewick Washington was 105 degrees out (40 C), and it was keeping up fine. It's 8 stalls, though, and not very heavily used, so it may be able to handle that better.
     
  10. AustinP

    AustinP Member

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    As asked above, did you try another stall? I’m now always checking the app to ensure charge speed is right. If not, and it happens frequently, I first try to unplug an replug and if not ok, I move the car. Often one of both does the trick.
     
  11. Rocky_H

    Rocky_H Active Member

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    I didn't really need to bother for a few reasons.
    40kW is still pretty fast
    I wasn't in any hurry, and I wanted to go over to get an iced coffee
    I wasn't all that low % when I got there, and I didn't have a very long drive to my next stop, so I figured I can leave pretty soon anyway and use up the rest of this range, and just use a faster stall from a lower % at the next place.
     
  12. Tesomega

    Tesomega Member

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    Sep 28, 2017
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    Location:
    Pittsburg, CA
    I have had slow charge speeds on several SC (Utah, Nevada, California) during my trip back from Salt Lake City. When i had reported to Tesla, they said there are not seeing any issues on their network. I was getting 60Kw charge rate at 32% SoC while the temperature was hovering about 100* F. I had tried to moving the car around several times with initial higher charge speeds for couple of % then going back to 60-70Kw charge rate.

    My experience is Low charge speeds is the no.1 cause of delays during long trips. I spent about 2 hrs or so more in charging time than planned in a station because of charge speeds (all of my charges were happening when there is no other cars charging in those SC)
     

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