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Can I use the Tesla UMC to charge my Chevy Volt?

Discussion in 'Charging Standards and Infrastructure' started by artsci, Mar 19, 2013.

  1. artsci

    artsci Sponsor

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    Now that I have my curbside charging station set up for my Model S when it arrives in April/May I'm very tempted to use it with my Volt until that time (with the J-1772 adapter). But I'm concerned that such a use would risk damage to the UMC or the Volt's system. Anyone know the technical stuff here? Is this too big a risk? Should I not even think about it?
     
  2. DCWitt

    DCWitt Member

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    Nope, the J1772 adapter allows j1772 charge station to connect to Model S. will not allow you to connect Tesla UMC to Volt.
     
  3. hcsharp

    hcsharp Active Member

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    If you had an adapter to go from Tesla connector to J1772 connector you might be able to do it. The adapter would have to be custom made because Tesla has no plans to make one, and you would have to wire the J connector different from what is standard.
     
  4. artsci

    artsci Sponsor

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    Overlooked the adapter question. It's not worth all the trouble. Thanks for the tip!
     
  5. hcsharp

    hcsharp Active Member

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    It would be much easier and cheaper to get a separate UMC for the Volt that went from NEMA 14-50 plug to J1772 with electronics in-between. You can buy these from multiple sources.
     
  6. GSP

    GSP Member

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    What would have to be non-standard? Couldn't you just connect the Tesla inlet pins to their counterparts on a standard J1772 plug? (assuming you could buy a Tesla inlet, of course)

    GSP
     
  7. hcsharp

    hcsharp Active Member

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    That might work but I doubt it. You'd end up with the wrong impedance on the proximity pin.
     
  8. bellwilliam

    bellwilliam Member

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    I am no expert, but I doubt it will work. otherwise you will see Volts, Leaf and Prius plug-in all pull into Tesla Supercharger Stations for a fill !!
     
  9. rpavlicek

    rpavlicek ***** Neophyte

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    Can you list some sources that could make (or have) such a thing? I'm interested.
     
  10. artsci

    artsci Sponsor

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    I have that already --- the EVSE upgrade (a Leaf UMC modified to charge the Volt at 240V). I was just hoping to be a able to use a single UMC to charge both the Volt and Model S. But as I'll be selling the Volt when the MS is delivered it won't be a concern for long.
     
  11. doug

    doug Administrator / Head Moderator

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    You guys should watch your terminology to avoid confusion. UMC is a Tesla specific term.
     
    • Informative x 1
  12. GSP

    GSP Member

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    An adaptor would not change impedance noticeably. Does Tesla's UMC have non standard resistors between proximity and ground (R6 and R7 in the J1772 recommended practice)?

    GSP
     
  13. hcsharp

    hcsharp Active Member

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    What is the proper terminology for essentially the same thing for another car?

    - - - Updated - - -

    It would change the impedance enough to be out of tolerance for most vehicles. Many EVSE also monitor the proximity wire and it would not work for them either. That's why I stated in an earlier post that you would have to wire it non-standard. Then you run into some thorny issues like how do you disconnect it from the car? Do you press the button on the J connector or the Tesla connector? If it's wired according to spec, neither one would make the car stop charging, if it ever started in the first place.
     
  14. jomo25

    jomo25 P4398

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    umc = evse
     
  15. hcsharp

    hcsharp Active Member

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    That's like saying Model S = car. The HPWC is also a EVSE. Until I hear a better idea, I'm probably going to call it a portable thing-a-majig for charging. No confusion that way and everybody will know what I'm talking about.:biggrin:
     
  16. jomo25

    jomo25 P4398

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    That's your call. But that's what Volt and Leaf owners call it. That is, when they are referring to it correctly, some call it a charge cord or adapter, which is wrong since the charger is actually on board, like the Tesla, and the cord is just an, wait for it, EVSE. :)
     
  17. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    Woo, technical term time! :)

    The UMC is an EVSE unit with a "Tesla type 2" coupling means (that's what I'm calling it!)
    The Volt thingamajig is an EVSE unit with a J1772-AC coupling means.

    NEC 625 defines an EVSE unit - it provides personnel protection against shocks (ground fault detection), automatic de-energization of the cable upon uncoupling from the vehicle or under heavy strain (someone driving off with it attached), and protection against backfeed of power stored in the car to the grid if line power is removed. Typically, this means an intelligent contactor with GFCI sensing.
     
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  18. jomo25

    jomo25 P4398

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    Yup. So, when I want to distinguish between wall mounted EVSEs and portable ones, then that's how I do so. I call them wall mounted (or fixed) EVSE vs. portable (or non-fixed) EVSE.

    The UMC is just a portable EVSE with a Model S specific connector. The HPWC is a wall mounted EVSE with Model S specific connector. Both with special Tesla specific names.
     
  19. Kipernicus

    Kipernicus Model S Res#P1440

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    This is what you want

    20130324_191743.jpg

    But no, you can't have it because this was at the Palo Alto HQ and it was probably created as a one-off by a Tesla engineer.
    Is it as simple as buying a Tesla UMC and replacing the connector? Or is some tinkering with the circuitry involved?
     
  20. tomsax

    tomsax Member

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    #20 tomsax, Apr 17, 2013
    Last edited: Apr 17, 2013
    I just put a friend's Model S UMC on an oscilloscope and it looks like a perfect J1772 EVSE. When simulating a connected J1772 vehicle, the pilot signal is a very nice 1.0004 kHz square wave with a 66.7% duty cycle, indicating a 40A current limit.

    It looks like it also implements the proximity pin. The resistances we measured don't seem right, 850 and 1,200 ohms, perhaps that was a measurement error. The proximity pin is implemented in the connector so it could be taken care of when doing the replacement.

    If you are facing the connector on the UMC, with the two large power pins on the top and the three smaller pins on the bottom, the ground is the center of the three, the small one on the left is proximity and the pilot is on the small right pin.

    I neglected to do the final step, asking it to turn on the power, but since everything looked right I'm confident that it would work with any J1772 compliant EV.
     

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