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Range dropping while plugged in overnight on 110v

Discussion in 'Model S: Battery & Charging' started by wts13, Jan 9, 2014.

  1. wts13

    wts13 Member

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    Here on my trip I've been plugging in the car overnight outside on a 110v. I got a few dozen miles added, then stopper during the day at the LV service center to charge almost all the way at their 14-50. Then last night I plugged the car back in. This morning the range is over 15 miles less than it was before plugging in, despite saying 'charge complete.' Usually the car only loosed a mile or two overnight if it's unplugged. Anyone understand what's going on?
     
  2. liuping

    liuping Active Member

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    It sounds like it did not go to sleep for some reason.

    I loose about 12-13 miles per day if it does not sleep, 4 per day if it does. (with mild San Diego weather, 50-60 at night in the garage in the winter)
     
  3. montgom626

    montgom626 Active Member

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    Always lose 7 miles per night.
     
  4. ChadS

    ChadS Petroleum is for sissies

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    What was the temperature when you plugged in it, and when you checked in the morning?

    While this might have changed (I don't recall seeing anybody mention it for a while; and I think one firmware update was supposed to address it), the car used to "hide" a lot of range - like, 25 miles - after a big temperature drop. Most of it wasn't really lost though; it would come back as the car warmed up.
     
  5. wts13

    wts13 Member

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    It was in the mid 30's if I recall. I called Tesla and they said that the power required to heat the battery for charging was greater than that provided by the 110 so the result was a net loss.

    Would be good if the car could provide a warning in situations like this.
     
  6. islandbayy

    islandbayy Active Member

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    The pack heater is approx 3.3kW, maximum on a 120v 15a outlet will be 1440 Watts, not quite half. Now, I believe it was with Firmware 4.5, their was a adjustment with the thermal management when plugged into a low voltage and low amperage power source (Your 120v outlets).
    What this did was when those are being used to charge, it would greatly lower the temp at which the pack heater would kick in, to allow charging (usually, the 120v outlets are used for emergency charging, so getting enough juice in to get ones self to a level 2 to finish is important).

    Now it can only be lowered to a certain point. Wind plays a important factor. If the temp is at or below 32 degrees and their is no wind, you are usually good down to 25 as long as it's plugged in and actively charging, as the charging keeps the cells just warm enough. Now, add wind to the mix, and that little tiny bit of heat generated will not be enough to keep the cells temperature's up high enough.

    You see, the problem with the Lithium Chemistry used, is that when the cells are at freezing or below, the process of CHARGING them actually DAMAGES them. Internally, what happens is the lithium starts to electroplate onto the Anode of the battery cells. This causes a PERMANENT LOSS OF CAPACITY AND WILL EVENTUALLY RENDER THE BATTERY USELESS.

    Some chemistry of Lithium Batteries will permit a EXTREMELY LOW charging speed below freezing, though still not recommended.
    Charging at all is allowed above freezing, though the closer the batteries are to freezing the lower the speed. This is why we have Regen limitation and Regen disabled.
    Fast charging, or in other words Supercharging, is ok when the cells are above about 45*F. Below that, and the speeds will be greatly reduces until the ideal temps are reached ( I have experienced this in Mauston Supercharger).
    Maximum temps for charging are approx 110*F. This is why we have nifty active cooling on our cars :) And also why Nissan says to Fast charge as little as possible (no active cooling on the Nissan Leaf)
    I do not have numbers for max temps for fast charging, sorry. And this is based on Standard 18650 Cells. I can't get more specific on the Tesla battery, as I believe they have tweaked the chemistry a wee bit.


    I didn't mean to get off topic, just saw a opportunity to turn this into a somewhat educational thread :)
     
  7. DriverOne

    DriverOne Member

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    One of the most interesting & informational posts. Thanks.
     
  8. efusco

    efusco Moderator - Model S & X forums

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    If you're not actively charging, being plugged in will NOT prevent loss of range. The exceptions being a)every 24 hours the car will wake up and automatically top up to your preset range limit and b)if your range drops below some Tesla determined threshold it will start charging (likely to only happen if you were very low to start with).

    In your case I would have probably charged to ~90% on the 14-50, then plugged into the 110v to allow it to top up overnight. Since you'll only get about 3 miles per hour of charge on 110v it will take most of the night (depending upon how long your nights are) to reach a maximum charge.

    Be aware, also, that if you're not using "Range Mode" the car will divert more of the 'juice' to keeping the battery warm/conditioned than it will in Range mode and thus your charge rate can be significantly slower in very cold weather.
     

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