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Charging Amp Question

Discussion in 'Model S: Battery & Charging' started by aollivierre, Nov 5, 2017.

  1. aollivierre

    aollivierre Member

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    Charging question for the group.


    As a new user, first thing I got completed was the installation of a 240 outlet in my garage. It’s a attached to my breaker as a 60amp.


    When I charge, the max rate I see is 40a. Should I see something faster on my car’s dash as a charge daily?


    Silly question I know but I am a newbie.
     
  2. Doug_G

    Doug_G Lead Moderator

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    The 240 outlet would be a NEMA 14-50. The maximum rated continuous load is 40A. The UMC knows this and that is the maximum it will draw.

    If you replace the plug with a wall connector, then you could set it to charge at 48A. That is the maximum continuous load for a 60A circuit.

    In practice, you are unlikely to need more power than 40A for nightly charging.
     
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  3. KJD

    KJD Supporting Member

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    If the outlet you installed is a NEMA-1450 then that outlet is limited to 50 amps. The Tesla Universal Mobile Charger (UMC) that comes with the car will limit that draw to 80% of 50 amps for safety reasons. This is why you are seeing 40 amps on the dash.
     
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  4. TexasEV

    TexasEV Well-Known Member

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  5. aollivierre

    aollivierre Member

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    Got it....So when the charge is doing its thing.....What number should I see on my screen specially next to the 40a number?

    Should it show 40/40a or something lower?
     
  6. ShockOnT

    ShockOnT ⚡️⚡️⚡️⚡️⚡️

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    It should show 40/40.
     
  7. aollivierre

    aollivierre Member

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    and if doesn't, get my installer back out? or do I possibly have a bad cable?

    I also noticed a reset button on my cable...What is that for?
     
  8. ShockOnT

    ShockOnT ⚡️⚡️⚡️⚡️⚡️

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    I’m sure your installation is fine, and a max 40A charge is normal.
    Don’t worry, 40A at 240V is plenty fast enough. I run my home charging at 25A/240V and the car is always finished long before I wake up, even if charging from totally empty to 100%.
     
  9. David29

    David29 Supporting Member

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    For an explanation of when to use the reset button, the UMC instructions are here: Model S/X Corded Mobile Connector
     
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  10. TexasEV

    TexasEV Well-Known Member

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    The first number is what the car is actually drawing at that time. The second number is the max available with the UMC adapter you’re using. 40/40 is what to expect with a 14-50 outlet when everything is working properly.
     
  11. brkaus

    brkaus Well-Known Member

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    You are using the EVSE? Plugged into a 14-50?

    It should have a 50a breaker.

    Max you will get is 40a.

    If it is lower than that, say “30/40”, you may have turned the current down manually. Hit the up arrow.
     
  12. aollivierre

    aollivierre Member

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    Great info and thanks. I will keep an eye on it to make sure nothing strange is happening.....but to everyone' point, my car charges fast enough. Always charged by the time I wake up in the morning.

    The fun thing on my end is the fact that I have a supercharger down street from my house...Just for fun.... :)
     
  13. Seawind300

    Seawind300 Member

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    Do you have "dual chargers" ? If you did't upgrade to dual chargers, you will only show 40a even if you we connected to a 100a HPWC.


    Mike
     
  14. Rocky_H

    Rocky_H Active Member

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    There are dozens of 240V types of outlets, and you didn't specify what type.
    NEMA connector - Wikipedia
    If it is the 14-50 that the Tesla mobile charge cable uses, that should NEVER EVER be on a 60A breaker. That is a violation of electric code. If that's the case, you need to get that changed to a 50A breaker.
    The mobile charge cable is only capable of pulling 40A maximum, so that's what you'll get. I will say that I and many other owners notice that the charge cable gets a little bit hot running at the 40A maximum rating, so I have it turned down into the mid 30's for daily use. It's still plenty fast enough, and keeps the cable and the electronics in it cooler.
     
  15. TexasEV

    TexasEV Well-Known Member

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    Don't confuse him. There haven't been "dual chargers" for a long time. There are two single charger options now, 48A and 72A, and what you get depends on battery size. There's not an option to chose one of the other.
     
  16. Seawind300

    Seawind300 Member

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    It was not my intent to confuse anyone. I have a 2016 90D and I had the second 40a charger installed after I bought the car so I can charge 80a it the charger can supply it. Tesla even calls it a Model S Dual Charger. I bought it in July.... not that long time ago :) If the OPs car can not receive this upgrade, I am truly sorry for my post if it was confusing

    Mike
     
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