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40 kW limit!

Discussion in 'Canada' started by sandpiper, Feb 23, 2015.

  1. sandpiper

    sandpiper Active Member

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    So, I had to put my wife's car in the garage last night to thaw off some frozen crud accumulated in the wheel wells. And the Tesla spent it's first night outside in the cold with no plug-in.

    This morning the thermometer read -32C. And the dotted line on the power meter was at 40kW! Yikes.

    I decided that this was one very unhappy car and moved it into the garage to plug in and preheat for a bit before leaving.
     
  2. Doug_G

    Doug_G Lead Moderator

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    Wow! I've never seen it anywhere near that bad. But I've not left my car outdoors overnight at that low a temperature.
     
  3. iKhalid

    iKhalid Member

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    What! I park outside every day and I have yet to see such a limit!
     
  4. Doug_G

    Doug_G Lead Moderator

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    Despite the protracted cold weather this winter, we haven't been that cold. My back yard weather station says the lowest temperature here was -27.1.
     
  5. sandpiper

    sandpiper Active Member

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    It was a first for me too. I leave it outside a work regularly, and we've had some solid -25 days in the last month. And the worst limit I'd seen previously was 120 kw.

    When I brought it in and plugged it in, I turned on charging (in addition to climate). It was drawing 45 amps but it didn't charge. Or at least it was showing a 0 km/h charge rate. I assume that the 45 amps was going to heat the battery to the point where charging was permissible? Does that make sense?

    When I left the house about a half-hour later, it had increased the power limit to 120kW and hadn't added any range.

    I get the sense that our climate is on the outside edge of what the Model S is designed for.
     
  6. Doug_G

    Doug_G Lead Moderator

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    You have a Supercharger in your garage? :tongue: I assume you mean 12 kW. That's the maximum power draw of the pack heater plus cabin heater. So yes, the car can draw all of that without charging. For a while.

    Lots of Teslas in Norway! At these temperatures ICE vehicles start having trouble, too. It's just cold!
     
  7. iKhalid

    iKhalid Member

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    Indeed. But if you think about it, there is a limitation in the nature of Li-Ion batteries when it comes to extreme cold weather. My cell phone for example turned itself off for insufficient battery after being outside for 10 minutes when it was -23°C, whereas the actual battery level was at 50% before I left.
     
  8. sandpiper

    sandpiper Active Member

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    No... I mean that the power output limit had gone up from 40kW to 120kW. A 12kW limit would probably not be enough to move the car!

    And yes... ICEs have difficulty at that temp too. Although they're quite a lot better than they once were. My wife's Audi fires up at those temps very easily.
     
  9. wk057

    wk057 Senior Tinkerer

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    Mind your warranty.... exposure to extreme cold for extended periods isn't covered by the battery warranty, although I've not yet read about a case where this was invoked.

    In addition, damage resulting from the following activities are not covered under this Battery Limited Warranty: Exposing the vehicle to ambient temperatures above 60°C (140°F) or below -30°C (-22°F) for more than 24 hours at a time;

    While it doesn't say keeping it plugged in avoids this clause, general consensus seems to be that keeping it plugged in would help and I agree. If you're going to leave it outside in cold like that, at the very least run a 12 gauge 120V extension cord over and leave it plugged in, IMO.
     
  10. sandpiper

    sandpiper Active Member

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    I'm very aware of that. This was a one shot deal. It will be going up to a balmy -18C here this afternoon, so no worries. And the Tesla will be back in her +20C home in the garage tonight!
     
  11. Kalud

    Kalud Member

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    Yikes ! 40kW is 54hp ;)
     
  12. sandpiper

    sandpiper Active Member

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    Yep! 0 to 60 in.... 40 to 50 seconds or so? :)
     
  13. wycolo

    wycolo Active Member

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    My MS has seen -31*C for two nights in a row last winter. So far this winter -25*C for two nights. But re the Warranty, it normally will get significantly warmer during the following day so not a Warranty issue if it does.
    --
     
  14. SmartElectric

    SmartElectric Active Member

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    Hmm, I "make do" with 55kW on a daily basis, and rarely want for more, but that's because my car weighs a fraction of the Model S. ;-)

    The Smart ED does reduce power in cold weather, but not to the extent (as a percentage of ultimate power) seemingly reported here.
    The ED has three power bars normally, and when it gets below -10C perhaps two, then when -20C there is a chance of seeing one power bar.
    At three bars, I have 55kW at my right foot, at two I have 40kW, and at one bar perhaps 20kW or less.

    Thus, even in very cold temps, the Smart ED has 40kW available.
    If I pre-condition (set a departure time in the smart phone app or via dash menu) in -20C, the car has minimum two bars available, and the cabin is room temperature. Pre-condition even works when using my 110V EVSE.

    It seems to me that Tesla is being more conservative in their relative reduction in available power compared to the Smart ED...
    Looking forward to getting a Tesla some day, that is for sure!
     
  15. Doug_G

    Doug_G Lead Moderator

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    The temperatures and percentages you report for the Smart are pretty similar to the Model S. When you're starting out with > 300 kW you've still got quite a bit of power at 35%. The 40 kW limit the OP describes is something I've never seen.
     
  16. EVFest

    EVFest Member

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    #16 EVFest, Mar 3, 2015
    Last edited: Mar 3, 2015
    He He, That is interesting! My Electricfly (EV Converted Firefly, with Lead Acid Batteries) uses just 14 kW to move its lighter (2,000 Lbs) down the freeway at 60 Mph/100 Kph! Story at Electricfly - MyElectricfly.com - the Blog Links off from the menu there!
     
  17. PoweredByRain

    PoweredByRain Member

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    School buses typically have 160 kW engines. Slightly larger weight, higher coefficient of drag and larger frontal area than a Model S. :) Of course, there are some hills they can only manage 30 to 40 km/h going up!
     

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