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Drop in Rated Range after 24 Hours?

Discussion in 'Model S: Battery & Charging' started by 0Q991, May 31, 2015.

  1. 0Q991

    0Q991 Member

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    Hi All,

    First time Tesla owner--got a 70D just 2 weeks ago.

    I charged the car on Friday night to 2 marks down from max. On Saturday morning, it showed 190 miles Rated Range. I unplugged the charger and did not drive it at all yesterday.

    This morning, I check the car and it shows 186 miles Rated Range.

    Is this normal?
     
  2. TexasEV

    TexasEV Active Member

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    Yes. Also you should not unplug the charging cable until you need to. "A connected Model S is a happy Model S."
     
  3. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    The Vampire in the Model S is thirsty and has to drink charge from the battery.

    As TexasEV, leave your car plugged in. My experience is that the Vampire will drink 8-9 rated miles, then the car will charge back up, repeat...
     
  4. 0Q991

    0Q991 Member

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    Thanks!

    I'm trying to avoid daytime charging rates. The charging menu only allows me to start charging at a certain time. So if that's 10pm and it's done by 1-2am, then the next day I don't drive the Tesla at all, should I unplug in the morning then replug it in at night? That way, I avoid daytime charging rates and allow it to recharge at 10pm again?
     
  5. Adrian

    Adrian Title(D)

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  6. TexasEV

    TexasEV Active Member

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    I don't think that's necessary. You're not going to notice the cost of charging a few miles.
     
  7. SteveS0353

    SteveS0353 Member

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    My experience agrees with Cottonwood. Once it's charged, the car won't charge again until the vampire drain has dropped your rated miles by 8 or 9 miles AND it's arrived at your selected charge time. There is no reason to unplug the car on days you don't drive it.
     
  8. 0Q991

    0Q991 Member

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    Great advice! I'll leave it plugged in over the weekend then (mainly drive the Tesla for my work commute).

    But, to reconfirm, a few miles of Vampire Drain per day is a normal amount, correct?
     
  9. SteveS0353

    SteveS0353 Member

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    #9 SteveS0353, May 31, 2015
    Last edited: May 31, 2015
    Yes, perfectly normal. The vampire drain is about 1.2kWh per day more or less. It's actually the power to run the on-board electronics when the car is not operating. The car supplies this from the 12V battery, which must then be recharged from time to time from the large drive battery. It varies with temperature, the sleep mode you have the car set to, and other factors. But it's perfectly normal to lose a few miles per day to keep the 12V battery charged.

    With charging set to start at a certain time at night, the car won't charge during the day. It will wait until it's lost about 8 or 9 miles of rated range (4 or 5 days not being driven), then schedule a charge cycle at your set time to top off the drive battery. That cycle will repeat as necessary.
     
  10. Knobby

    Knobby Member

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    Yes this is how it works. It will not top up until the scheduled time. I do this all the time, as I'm often away for several weeks at a time. I just leave it plugged in and every 3 or 4 days it tops up, after the set time in the evening.
     
  11. supratachophobia

    supratachophobia Active Member

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    Also, you may notice the mileage go up of you, for example, park in a hot parking lot for the day. It seems the batteries can different voltage readings to the car based on heat of cells.
     
  12. 0Q991

    0Q991 Member

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    Thanks, all! Great info for a Tesla newbie.
     
  13. Incredulocious

    Incredulocious '11 LEAF –> '13 RAV4 EV

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    I'd like to take this opportunity to say that while this is normal for the Model S, it shouldn't be. (Yes, I realize it was actually much worse before.) Other electric cars, including some whose drivetrain and battery system is provided by Tesla, have active electronic systems waiting to respond to cellular network commands and to respond to the approach of the key fob but don't have such significant vampire drain. (As in not noticeable amounts over several weeks.)

    Here's hoping Tesla will eventually reduce this loss of energy with more power-efficient systems, comparable (or better) than other manufacturers! Go Tesla!
     
  14. SteveS0353

    SteveS0353 Member

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    #14 SteveS0353, May 31, 2015
    Last edited: May 31, 2015
    100% agree. In fact, the Model S vampire drain has been leading to wear out and replacement of 12V batteries in typically 12-18 months. It should be an order of magnitude or more lower than it is. 1.2kWh is equivalent to 50W burning all the time. There is a really interesting thread in which I made several engineering calculations, supported by other members. Check out this thread if you want to learn more.
     

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