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Possible solution to short J1772 cords?

Discussion in 'Charging Standards and Infrastructure' started by Odenator, Aug 18, 2013.

  1. Odenator

    Odenator Member

    May 2, 2011
    Olympia, WA
    I have received a couple of parking tickets for backing into angled EV charging spots because of short EVSE cords. I was wondering if anyone has attached a J1772 to Roadster adapter to a Roadster to Model S adaptor to get extra length out of the charging cord? Would this even work?
  2. TsRocket

    TsRocket Member

    Nov 21, 2012
    It is supposed to work, i bought one, but do as you do, back in at angle. Rotten, money-grubbing cops.
  3. FalconNinetyD

    FalconNinetyD Active Member

    Dec 20, 2010
    Sounds like about $1200 in adapters. How much are the parking tickets?

    This looks to be less expensive:
    J1772 Extension Cord
  4. wycolo

    wycolo Active Member

    May 16, 2012
    WA & WY
    Don't use 'short' and 'cords' in the same sentence, please - ouch!! Use maybe 'not long enough' or similar.--
  5. essaunders

    essaunders Member

    Jun 6, 2012
    Nashua NH area
    Nice solution - I'd caution that it isn't fool proof - one needs to ensure not to pull more than the rated current through it. If you plug it into a 80A Clipper Creek and then into a Dual charger Tesla you run the risk of excessive energy loss (heat) in the cord. I wonder how much more it would cost to to make the thing a proper EVSE to only set proper cord-limited max current.
    kinda like this
  6. RandyS

    RandyS Fan of Elon

    Jul 8, 2012
    San Diego
    This one works for me....Just used it the other night....

    Modular EV Power

    Plug the public J1772 cord into one side of the adapter. Then you can plug in a 14-50 cord set on the receptacle and run that to the car...

    Never be ICE'd again....
  7. Robert.Boston

    Robert.Boston Model S VIN P01536

    Oct 7, 2011
    Portland, Maine, USA
    This looks interesting, especially if one relies on public charging a lot. I'd be interested to hear feedback from the electrical safety experts about this. I'm also interested in how the gadget spoofs the J1772 control signal -- how can it tell whether you are drawing 30A, 40A, 70A, or 80A? Or is this just a non-issue?
  8. TonyWilliams

    TonyWilliams Active Member

    Jun 11, 2012
    San Diego - Tesla powered Rav4 EV
    #8 TonyWilliams, Aug 30, 2013
    Last edited: Sep 10, 2013

    The Modular EV J1772 to NEMA 14-50 adaptor spoofs the car side of the protocol with a 2.7k +/-5% resistor from the proximity pin to ground. For some reason, they decided to put 6" - 8" of blue wire with the proximity pin inside the box that should have had an insulated twist wire nut on it; the yellow wire nut was not installed, but was just bouncing around in the box!


    The EVSE generates the pilot signal through the pilot signal which obviously also goes nowhere since this all terminates in a NEMA 14-50.

    From the car side of the proximity pin side, there is switch (S1) that connects the proximity pin to ground through the 1.3k resistor (I physically can't see it since it is epoxied in). In addition, there is another 2.7k resistor in parrallel that normally goes from the pilot pin to ground. finally, there is a diode.

    When S1 is open, only the 2.7k resistor is connected to ground. When this switch is closed, the combined resistance (1k * 2.7k) / (2.7k + 1.3k) should be 880 ohms, which tells the onboard charger to pull current in State C.

    State A = not connected, +12 volts DC
    State B = ready and connected, 2.7k car side resistance, 1kHz square wave +9/-12 volts with pulse width determining how many amps the EVSE has available
    State C = charging, switch S1/S3 (depending on which diagram you're looking at) is open on car, 1.3k resistor added in parallel to 2.7k resistor, 880 ohms overall, +6/-12 volts
    State D = ventilation for lead acid batteries!!!! The Modular EV adaptor obviously has no logic to send this signal
    State E = error, 3 / -12 volts, which this unit can't send either
    State F = ???, 0 / -12 volts, can't do it either

    So, you could pull as many amps as you want, right up until you smoke something, or the circuit breaker pops. Hopefully, most folks will respect that most public J1772's are 30 amp only, and not pull more than that just because the pilot signal isn't protecting the EVSE and power circuit.



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