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Is the Charging port DC or AC?

Discussion in 'Model 3: Battery & Charging' started by CWFLY, Jun 14, 2018.

  1. CWFLY

    CWFLY Member

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    Just curious... Is the charging port (where we plug into the car) DC or AC?
    Anybody know the electrical specs, protocol, etc?
     
  2. jelloslug

    jelloslug Active Member

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    The answer is yes.
     
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  3. Petra

    Petra Member

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    Both. L1 and L2 EVSEs feed standard AC to the charge port (either 120V or 240V for residential and 208V for industrial) and the car sends it to its onboard charger, which feeds DC to the battery. When a Tesla Supercharger is connected, the car's high voltage junction box switches over to feed the DC from the Supercharger straight into the battery.

    The port is J1772 compatible when AC charging (standard documents are available online, a physical adapter is provided with each Tesla--the adapter doesn't have any smarts) & is Tesla proprietary when DC charging.
     
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  4. CWFLY

    CWFLY Member

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    Nice summary. Thanks.

    That leads me to a follow-on question about the UMC.

    I was previously thinking that the UMC was an AC-to-DC converter because it seems to get fairly warm when in use. After reading the above, my guess is that it may not be. I'm curious about exactly what the UMC does. Seems like it provides an extension cord, physical adapter, and some handshake protocols via extra pins. Feels heavy, as if there is a big transformer inside. Is there any voltage conversion (ac-ac, ac-dc)?
     
  5. dhrivnak

    dhrivnak Active Member

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    No conversion as it feeds AC to the charge port. There is a contactor inside to ensure the is no voltage applied to the pins unless connected to the car and the car is ready to charge. And since the real charger is in the car it tells the car the maximum power that can be pulled.


    And if you think it is big you should see the monster adapter for the 1.5 Roadsters.
     
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  6. TexasEV

    TexasEV Well-Known Member

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    The UMC is an EVSE, just as the Wall Connector (formerly HPWC) is. That’s even bigger than a UMC, but is made to handle more power.
     
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  7. Petra

    Petra Member

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    Correct, the UMC doesn't do any AC to DC conversion for the car. The UMC provides a pilot signal to the car to inform it of the maximum allowable current draw, has contactors inside to cut power to the charge handle so it's not being plugged/unplugged while hot or energized when it doesn't need to be, it also provides ground fault detection, stuck contactor protection, etc.

    EVSEs (like the UMC & Tesla Wall Connector) are basically smart power cords and you can even build your own. Here's mine (though, I've since cleaned it up and upgraded it to include the newer WiFi module):
     
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