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Range charging/Balancing 85Kwh

Discussion in 'Model S: Battery & Charging' started by UGM, Feb 14, 2016.

  1. UGM

    UGM New Member

    Oct 12, 2014
    My wife had to go on a long drive today so I range charged the car.

    It was sitting on 87% charge when I started charging.

    3 hours and 15 minutes later it was still charging (at 99%) and it said that it had added 18 Kwh.

    We had to unplug the car because she had to leave so it never got to complete the charge.

    In other words it might have added another 1 or 2 Kwh before getting to "Charging done".

    Is this simply a sign that the pack was extremely unbalanced before I charged it or is something else going on?

    13% of the battery capacity should be around 10 Kwh not almost 20 - unfortunately:smile:.

    The pack was -2C cold when I started charging but the power it used for heating the battery was not counted as added Kwh.

    I checked because I was interested in how long it needed to heat the battery before actually starting to charge.

    All the best
  2. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

    Mar 8, 2012
    #2 jerry33, Feb 14, 2016
    Last edited: Feb 14, 2016
    There are two hypothesis: One is that the pack is being balanced, the other is that the pack is just getting the last little bit filled, and that the pack is always being balanced. Tesla service personnel are of little help because there are some that favour one or the other. Interestingly, my car did that when new, but it hasn't done it recently (past couple of years). Although I haven't ranged charged since last October.

    WK57, who has done a lot of work on this with a non-functional car, has determined that pack balancing triggers at 93% SOC, and then happens all the time until the pack is fully balanced (regardless of SOC). Others say that the trigger point is not based on the SOC, so we don't know if the 93% is correct or unique to that particular car.

    There has been some new discussion here which reconciles the two hypothesis.

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