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Is this rated range display behavior normal ?

Discussion in 'Model S: Battery & Charging' started by taurusking, Nov 24, 2014.

  1. taurusking

    taurusking Member

    Joined:
    Jul 12, 2014
    Messages:
    876
    Location:
    East Texas
    Hi All

    So I had weird situation this morning:

    Have been charging to 90% every day and turned on the climate control before all the charging is complete and 40 minutes before I left the house and set the heat to 90F. This is what I have been doing every day.

    Usually after I turn the climate control on I notice that the charging rate drops from 30 miles/hr to 19-20miles per hour.

    My rated range has been 231 miles since the cold weather started. My rated range (When I bought the car in the month of October) was close to 238 -240 miles but I figured it could be due to the cold weather.

    This morning after I started the car and drove 2 miles my rated range was still at 231 miles.

    Question:

    It seems like the computer froze or something and that my rated range miles did not decrease from 231 until I drove 3 miles. Does this mean that rated range was 234 miles and the computer froze and did not display correctly?

    The attachment shows that I took picture at 2.1miles from my home with rated range still at 231miles




    photo.JPG

    I also started to hear small humming noise from the 17 inch screen. Does anybody know what it is ? Does high interior temperature cause computer freeze?

    Thanks
     
  2. mmh

    mmh Member

    Joined:
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    Messages:
    122
    Location:
    SLC
    There is no way to know exactly how much energy is in a battery, you can only guesstimate based on measured voltage. The Tesla does a lot of math trickery to try and get as accurate a guess as it can, because of that, you'll sometimes see "free" range appear.

    You'll also notice if you ever drive a lot of short distance trips for weeks on end, your total chargeable range will decrease, e.g. a 90% charge start at 231RM, but after a few weeks it might be 229RM. But you'll notice after a long drive (200+ Miles) then next time you charge to 90%, it'll be back up to 231RM. This again is caused my the computer recording historical battery usage/range and guesstimating remaining capacity and energy in the battery.
     
  3. gg_got_a_tesla

    gg_got_a_tesla Model S: VIN P65513, Model 3 Res Holder

    Joined:
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    The rated range estimate is just that, an estimate. It not budging from 231 for a couple of miles is perfectly normal, particularly in cold weather when the initial estimate may be a bit conservative and gets more accurate as the battery warms up.

    As for the humming, yes, there's a fan that comes on to keep the touchscreen and the electronics behind it cool when the interior temp gets very high.

    Speaking of which: preheating to 90 degrees?! Wow!
     
  4. taurusking

    taurusking Member

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    Location:
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    O.k realistically I might have misunderstood shore power and battery heating....I thought battery pack warms up when the interior temperature is set high .. and that all the energy is used to heat the cabin and also the battery pack.

    Am I wrong?

    I see the charging rate drops to 19-20miles /hr indicative of energy used to heat cabin and warm battery pack

    Please correct me if I am wrong
     
  5. gg_got_a_tesla

    gg_got_a_tesla Model S: VIN P65513, Model 3 Res Holder

    Joined:
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    Messages:
    6,097
    Location:
    Redwood Shores, CA
    Yes, shore power does get used to preheat the battery when climate control's turned on - except if the AC is set to be in Range Mode - but, not sure you need to turn the heat up to such a high level. I may be mistaken, but, AFAIK, just having the HVAC on will get the battery heat going.
     
  6. mmh

    mmh Member

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    Location:
    SLC
    #6 mmh, Nov 24, 2014
    Last edited: Nov 24, 2014
    I've found in the winter, the easiest way to preheat the battery (which should only needed if driving a long distance), is to use scheduled charging and time it to be completed about 30 minutes before I want to leave. While charging, the car will preheat the battery. Then you don't have to worry about warming the cabin to uncomfortable hotness.
     

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