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Power charging question

Discussion in 'Model S: Battery & Charging' started by kwjayhawk, Sep 11, 2016.

  1. kwjayhawk

    kwjayhawk Member

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    I'm sure this will sound like a noob question, but I'm trying to learn more on how Tesla charges the batteries in their pack. Maybe this is a question in general of all multi-celled batteries:

    Is it like a hose that has to fill up cups, in this case cells, that goes from cell to cell to fill or rather a hose that sprays an area at once in which each cell is filled at the same time.

    Or is it something entirely different? If someone can help point in the direction of learning more that would be great. The Tesla graphics and info seem to explain only how fast it takes but not the charging itself.
     
  2. mspohr

    mspohr Active Member

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    All cells are charged at the same time.
    This allows faster charging since each cell can be charged at its 1C rate and heat buildup is spread out to the whole pack.
     
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  3. Skotty

    Skotty 2014 Model S P85

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    Generally speaking, it charges all at the same time, and the charge rate has to go down as the batteries near 100%.
     
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  4. Saghost

    Saghost Active Member

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    The battery pack is made up of sets of 74 cells in parallel, either 84 or 96 of them in series. The charger raises the voltage of the entire string together so that electrons flow into the pack.

    Because the series sets all have similar internal resistance, they receive approximately equal percentages of the influx. Each set of 74 cells in parallel has exactly the same voltage across every cell in the set, so they all get the same charge together.

    If any of the sets got less charge than the other ones initially due to minor differences in resistance, the long later portion of the charge cycle at constant voltage should bring them up closer to the rest.

    At least, that's my understanding. I'm not really an expert on the subject - I had a few classes once...
     
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  5. kwjayhawk

    kwjayhawk Member

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    Thanks everyone!
     

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