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Overcharging from HPWC

Discussion in 'Model X: Battery & Charging' started by aesculus, Jun 25, 2017.

  1. aesculus

    aesculus Still Trying to Figure this All Out

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    Last Friday I had a full day of EV trips running to/from the airport multiple times. At the end of the day I plugged into my HPWC (car set to 72 amps on 100 amp circuit). The car was at 14% when I plugged it in and the charger was set as usual to timed delay charging at 11PM.

    I have turned off charging notifications on my phone since they started sending out sound alerts so I am not sure what the charging state was early Saturday morning. But when I went to check the app on Sunday AM, I noticed it was at 94%. I went to the car and verified that it was indeed set to max at 90% where it always resides.

    Any thoughts on why the car exceeded the 90% level that was set?
     
  2. MasterT

    MasterT Member

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    Did you get a firmware update recently?
     
    • Like x 1
  3. aesculus

    aesculus Still Trying to Figure this All Out

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    Nope. 17.14.23
     
  4. MasterT

    MasterT Member

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    I've read another post where they reported battery was charged to 95% while being set to 90% after a firmware update, that's why I asked.
     
  5. travwill

    travwill Active Member

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    I’ve had this happen a few times. In my case the car completes at its usual RR, but in checking back later it seems to add a few extra percent on top of that after completing.

    I thought it was warmer weather at times or now just figure it is the BMS doing its thing.
     
  6. aesculus

    aesculus Still Trying to Figure this All Out

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    OK. First time I noticed it but since I don't have the app notify me of charging complete, it might have happened before.

    Have not noticed it again since.
     
  7. mal_tsla

    mal_tsla Member

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    Lithium ion battery state of charge is estimated. Sometimes the estimate gets revised based on observed cell behavior.

    Most likely your car stopped at what it expected would be 90% and later decided it seems like the battery has 95% charge.

    The only way to really know how much capacity the battery has is to discharge it fully.
     
    • Informative x 1
  8. K-MTG

    K-MTG Sunshade Captain of TMC

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    The car charges above the preset limit when you charge the car from a low state, such as under 50 miles.
     
  9. aesculus

    aesculus Still Trying to Figure this All Out

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    That was not the issue though. I was still around 14% when I plugged it in. Since that was about as low as it's been for months, that probably triggered the recalc as @mal_tsla pointed out.
     

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