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Supercharging the 70D

Discussion in 'Model S: Battery & Charging' started by Berty1970, Jul 13, 2015.

  1. Berty1970

    Berty1970 Member

    Joined:
    Jun 4, 2015
    Messages:
    49
    Location:
    Montreal, QC, Canada
    Hello everyone,

    As promised, I have taken data down when supercharging my 70D. I have supercharged her 4 times so far. The attached graphics are from 3 supercharging sessions. There were 2 in Drummondville on Supercharger 1A and 1 at the Ferrier Street Tesla Store on 1B (as per Kushari's suggestion). For that last supercharging session, there was another Tesla charging next to me on 1A. This may explain the less that linear graph for a section of the data. I took pictures of my screen every minute (I missed a few but very little, gaps in the first few graphs). That is the first series of 3 graphs. Then, I combined the data in a less than rigorous scientific fashion. The curves are pretty linear regardless of the supercharging session therefore I used the percentage of battery as the common point to merge the data together.
    attachment.php?attachmentid=87254&d=1436801981.png attachment.php?attachmentid=87255&d=1436801982.png attachment.php?attachmentid=87256&d=1436801982.png

    Now the merged data:
    attachment.php?attachmentid=87257&d=1436802015.png

    This last graph shows the additional data that I put in the merged graph. The data points don't align as I'm no Excel expert. What I did was to include the overlapping data points for X axis 31 and further i.e. battery percentage of 61% to 89%. If you transpose visually to x-axis 31 or battery % 61%, you will see that the data is superposable.
    attachment.php?attachmentid=87258&d=1436802156.png

    So, essentially, it seems that you get the same performance for supercharging based on your battery percentage. I used only percentages and kW for these graphs but will be doing the same exercise again for km/hr recharge. I just couldn't figure out the formula to transfer the kW into km/hr recharge. It was late last night. Anyone welcome to contribute.

    Hopefully this is useful to you.

    Regards,

    Berty.
     
  2. Oba

    Oba Member

    Joined:
    Jun 7, 2015
    Messages:
    234
    Location:
    SoCal
    It's interesting that they even bothered to make it hit almost 120kW for such a short time. But, the equipment can do it, so why not?

    I pulled 367 amps maximum with about 6-8 miles remaining two days ago, so my data corresponds to yours. While the 70D and 60 share the same battery voltage, it appears that more amperage is possible with 70D for a slightly faster charge rate. At the lowest battery voltages, it charges as fast as the fastest Tesla to date.
     
  3. daxz

    daxz Member

    Joined:
    Nov 15, 2011
    Messages:
    149
    Location:
    Denver, CO
    There are lots of online curve fit calculators. Here is which takes lots of data inputs:
    Calculate Polynomial Regression Online

    20%-80% fits pretty decently into a*e^(b*x) - to get the tails accurately lots of polynomial coefficients are needed (15)

    please share any equations as I'm really looking for f(percent) = minutes. Best charging time could be calculated by f(percent desired) - f(percent starting).
     
  4. Berty1970

    Berty1970 Member

    Joined:
    Jun 4, 2015
    Messages:
    49
    Location:
    Montreal, QC, Canada
    Hi,

    This is not actually a calculation to fit a curve as I did during my studies. These are simple graphs of raw data, real world data of me supercharging my 70D. This represents only my car. It would be great to see other graphs from other cars!

    My car is 2 weeks old and currently has 2,873 kms on it. This shows that I love it!

    I can post my data in the excel sheet if that is permitted. If not, and if you are interested in seeing my data, please PM me.

    Regards,

    Berty
     
  5. Oba

    Oba Member

    Joined:
    Jun 7, 2015
    Messages:
    234
    Location:
    SoCal
    #5 Oba, Jul 17, 2015
    Last edited: Jul 17, 2015
    Here's today's charge session at about 70 degrees ambient and 7 rated miles remaining, and 282v starting voltage.

    My car is three weeks old with over 3000 miles (5000 km):

    Min - Rated Miles - Volts - Amps - kW - Calculated@ 287 Wh/mile

    0 ------- 7 --------- 282 --- 0 ------- 0 ------------- 0 ----
    1 ------- 9 --------- 310 -- 367 -- 113.7kW ------ 396mph
    2 ------ 21 --------- 316 -- 360 -- 113.7kW ------ 396mph
    7 ------ 49 --------- 322 -- 335 -- 108.8kW ------ 379mph
    10 ----- 65 --------- 324 -- 305 -- 98.8kW ------- 344mph
    15 ----- 92 --------- 327 -- 254 -- 83.0kW ------- 289mph
    20 ---- 113 --------- 331 -- 216 -- 71.5kW ------- 249mph

    I got bored and quit here.
     

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