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Total kWh Battery Capacity and Total kWh Used Question . .

Discussion in 'Model S: Battery & Charging' started by Seegem, Mar 20, 2013.

  1. Seegem

    Seegem Member

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    Hi Everyone,

    I just did my first road trip in my Model S (P85): NYC to Newport, RI. It was an awesome drive and this car just became even more awesome on my hyper-awesomeness meter (already off the charts).

    I used the Milford Superchargers on both legs of the journey, because.. why not (they're conveniently at the midpoint). The total distance each direction is 180 miles (360 mile round trip journey). I went fast (~80 mph most of the way); it was cold and snowing (I had the heaters on, defroster on, etc.). When I completed the first leg, I noticed that the total kWh used was about 76, and on the way home the second leg total kWh used was 77.4. Total for the trip 153.4 kWh. That's well within the 85 kWh total capacity (for each individual leg of the trip).

    MY QUESTION: Does that mean, therefore, that I could have driven the entire leg without recharging? (since I never used more than 77.4 kWh). Am I analyzing this data correctly?

    Thanks so much!

    Mark photo.JPG
     
  2. mnx

    mnx 2013 P85

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    That sounds correct to me, with the exception that the usable capacity of the 85kWh battery is 81.5kWh.
     
  3. Seegem

    Seegem Member

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    Hi MNX,

    Thank you, that's very useful. Where did you get the info that usable capacity is 81.5?

    Thanks!

    MS



     
  4. mnx

    mnx 2013 P85

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  5. Seegem

    Seegem Member

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    I also got this from my DS at Tesla:

    Hi Mark,

    To answer your questions simply: Yes! You could have completed each leg without stopping as long as you performed a full Max Range recharge at your destination.


    That said, the vehicle does reserve a 1-3 kWh of power for auxiliary and ancillary systems that keep the car performing correctly. In addition, even in Max Range mode, the car leaves a bit of space open in order to move power efficiently between the inverters and battery. Your battery will hold slightly less that 85kWh in the same way a computers hard drive will alway hold slightly less than its stated capacity because it needs to be able to move files around during standard processes. While I'm not sure of the actual Wh quantity left open, I imagine your friends assessment is pretty close to accurate.


    Long story short, it would have been incredibly close but very possible. I think you were right to "top up" when you did. Congrats on the excellent road trip! I hope you have many more in the future!


    Best,
    Nathan
     
  6. Kipernicus

    Kipernicus Model S Res#P1440

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    Interesting info. By charging up in the middle it just leaves much more room for error and the unexpected. And is gentler on the battery for long term life.

    Anyone know the usable capacity of the 60? I've never pushed mine very low.
     
  7. Al Sherman

    Al Sherman It's about THIS car.

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    The really cool part is that the 1 way mileage is so close to the number 177 that ChadS has been preaching all along as the don't worry about range if you're under this number. Kudos to Chad!
     
  8. stopcrazypp

    stopcrazypp Well-Known Member

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    Any primary sources for this (all of those are secondary and don't show where they got the number from or how they got it)? I always assumed 85kWh was the usable (from range charge all the way down to the point where the car would not move anymore). This may change some calculations that were done over at the anti-EV thread about battery impact.
     
  9. bluetinc

    bluetinc Member

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    I think the discrepancy is that most people on here are talking about the amount of energy available from full until the car shows a "rated range" of 0. Thanks to Broder, we know that the car really has about 15-19 more miles left in it. At about 305 Wh/mi that adds on the "missing" 5 kW. I glanced at some of my data, and I have noted one leg of a trip at 260.9 mi, 79.4 kWh (305 Wh/mi avg) with 1 mile "rated range" left. With a 17 mile "reserve" that would be a total capacity of 84.9 kWh.

    Peter
     
  10. mhpr262

    mhpr262 Member

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    You used the Milford Superchargers? did you find them on your first attempt or did you have to drive around in circles first :-D
     

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