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Reduced Charging Rate at Super Charger once reached enough charge to next stop.

Discussion in 'Model S: Battery & Charging' started by gimmi80, Sep 8, 2015.

  1. gimmi80

    gimmi80 Member

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    Pittsford, NY
    I used the "incognito" smiley face because this is more of a suspect than a statement, however here is my experience from today.

    I drive quite a bit (~3500 miles a month) and as a consequence I get to supercharge quite a bit. Today I noticed something strange.

    Today was a 10-15 minutes session and I happened to sit in the car while charging. I started from 10% SOC charging at 110kW. Obviously it quickly went down settling around 85kW.
    Nav was running to my final destination, therefore I had a count down in minutes of the residual time (around 10-15 minutes as previously stated). Once I reached 40% charge the timer went to zero (I was charging at 70-75kW by then) at I got the message "Enough charge to reach destination".

    As this is my usual commute I know that if I drive with a more "sporty" style (what I was planning to do) I get home with ~5% battery and as I had to run a few errands I decided to sit there and wait a few extra minutes to pick up a buffer.

    I noticed that after the "enough charge to reach destination" message the charge rate dropped very quickly to 35-40kW. The drop in charge rate was much much fast than what I witnessed during the previous 10 minutes of charging session. I would define it artificially induced... it was so fast that it felt software induced... Volts were stable but Amps were varying widely and going down pretty fast.

    Well, I decided to cancel the NAV and to set a destination much further out than my home and in a matter of a couple of minutes the charge rate bumped back up to 65-70kW.

    What do you think? Are we experiencing software controlled reduction of supercharge rate to discourage "Excessive" supercharging?
     
  2. MikeC

    MikeC Active Member

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    Possibly, based on what you describe, but I don't think it ever makes sense for them to slow down Supercharge rates because it will slow down the turnaround time and clog up the spots for everyone else, making the problem worse. I don't really think it's an incentive to leave faster, people will still charge to the level they feel comfortable. Until the nav improves further and can calculate things like wind speed and driving style, they would have to use a generous judgment of what "enough" charge is necessary.
     
  3. LJordan

    LJordan Member

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    I just returned from a road trip and I saw something similar on a few charging sessions. However, it was not tied to the "Enough charge to reach destination" message. My situation appeared to be related to battery cooling. It seemed like a thermal limit was hit causing the charging rate to drastically reduce. After a few minutes, the rate ramped back up to normal levels.
     
  4. FlasherZ

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

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    I'm not experiencing that.

    What it will take for us to make such a determination is a) better, more granular data (e.g., the full curve from TeslaMS or VisibleTesla or the like); and b) additional reports of the same behavior from other cars, other Superchargers, and ruling out other items (like the temperature indications above).
     
  5. David99

    David99 Active Member

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    Might be a coincident. I doubt Tesla would do that. It makes no sense. If you feel you need more because of weather or driving style you will wait, and slowing down the charge rate would just make you occupy the Supercharger longer. No one will leave earlier because the charge rate is slower.
    Elon once said it's always better to charge to 100% than to arrive at 0%. In other words, if in doubt, charge more!
     
  6. gimmi80

    gimmi80 Member

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    Yes slowing down charging would result in longer time at the stall, and it would end up being counterproductive.

    I did not think about thermal limit, that could have been responsible for the reduction in charging rate.

    I'm also glad to see that FlasherZ is not experiencing this.
    Probably it was just related to thermal and/or other factors.
     

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