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Taper at home now with HPWC... seems so!

Discussion in 'Model S: Battery & Charging' started by scottm, Nov 20, 2016.

  1. scottm

    scottm Active Member

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    #1 scottm, Nov 20, 2016
    Last edited: Nov 20, 2016
    I seldom charge above 90% at home on my HPWC (100A circuit, dual on-board chargers so 80A possible).

    For the last few months, I've taken to setting the Amps at home to 64A instead of the maximum possible 80A, to be kind the handle and chargers.

    Today, I wanted to top up for a trip in the morning. The car was sitting at maybe 85%. So from the App I bumped the dial up to about 95%. Away she goes and starts charging at 64A all is good. I noticed after reaching 90%, the charging started to slow, and I see on the App the Amperage setting has dropped and was dropping slowly.. .48A.... 46A..... 44A.... and time is stretching on. It took a long time to hit 95. The voltage was good all the while, 236V or so.

    I swear before that charging would rage forward at the set Amperage held constant with the battery sucking it all up until the set point was reached, even if it was 100%.

    Now, it's tapering off like a SuperCharger..

    In all fairness, it's cold in the garage these days. So I know the battery is heating and I've turned on interior heat too, from the App. But for the last two winters, I'd do this too, and the charging App would be pegged at 80A all the way... (I'm pretty sure).

    Anybody else notice this?
     
  2. DarkMatter

    DarkMatter Member

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    That's exactly how lithium ion batteries charge, regardless of the power source. You must wait for the last part of the charge to chemically happen. You are remembering things inaccurately.
     
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  3. ecarfan

    ecarfan Well-Known Member

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    I think you are "misremembering". ;) Whether you are charging on a 10A circuit or a 200A circuit, there is always a taper as you approach 100% SOC.
     
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  4. scottm

    scottm Active Member

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    Ok, cool. It all makes sense and everything

    Like I say, I seldom charge upward of 90 at home maybe once per year... so it's been a while since last seeing this at home. It might actually be the first time I've ever paid attention to the details when going over 90 on HPWC

    I was just curious and now I know to allow more time to hit max charge when it's needed.
     
  5. TexasEV

    TexasEV Well-Known Member

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    No, it's not tapering like a supercharger. A supercharger starts tapering much earlier. And yes you are misremembering. It's always done that.
     

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