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Pre-conditioning while using the UMC charger

Discussion in 'Model S: Battery & Charging' started by 12Pack, Sep 4, 2017.

  1. 12Pack

    12Pack Member

    Joined:
    Aug 25, 2017
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    Location:
    Manchester, UK
    I'm charging at home off the UMC for now. So that's ~ 240V/10A = 2.4kW here in the UK. But I've heard that the climate control can use up to 6kw, and there's draw from the battery heater as well?

    If I pre-condition while on the UMC, does the climate system then draw down the battery, or just the mains, or both? Is there a set sequence in which this occurs?
     
  2. GaryREM

    GaryREM Member

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    Jul 16, 2013
    Messages:
    426
    Location:
    Fairfax, VA
    It shouldn't be different in the UK.

    When you are plugged in to mains, the car will draw power preferentially from the mains. If it needs more, then it will draw from the battery.

    Surprised you are limiting to 10A, really low.
     
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  3. 12Pack

    12Pack Member

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    Aug 25, 2017
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    Location:
    Manchester, UK
    Thanks. Yes, 10A is low - just using a regular mains outlet. Will install something more in time - but for my normal ~80 miles/week this is good enough for now.

    Does sound like I may end up drawing from the battery if I pre-condition when the garage temperature drops in the winter.
     
  4. Rocky_H

    Rocky_H Active Member

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    Feb 19, 2015
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    Location:
    Boise, ID
    Yes, cabin climate control heater can be 6kW and the battery heater can be 6kW, but keep in mind those are the maximum draws. They aren't always at that level. So they may be high for the first several minutes but will turn down in a little while. Also, there does not seem to be a mechanism to "turn on" the battery heater. So when you pre-warm the inside cabin, it still generally won't turn on the battery heater with that. It's a little bit of a workaround, but charging does generate some heat in the battery, so sometimes people charge for a half hour to hour in the morning to get that battery pre-warmed.

    I don't know of any kind of sequence to it, but it does preferentially use wall power. If you turn on heating in the morning, and it needs to draw 4-5kW, it will draw all of your 2.4kW from the wall and some extra from the battery. As the temperature gets stable, it will draw less from the battery while still taking your 2.4kW from the wall.
     
    • Like x 1
  5. 12Pack

    12Pack Member

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    Location:
    Manchester, UK
    Thanks - clear.
     

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