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HPWC cable for on-trip usage: good idea or horrible?

Discussion in 'Model S: Battery & Charging' started by AudubonB, Jan 29, 2015.

  1. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    Problem: we keep the provided charging cable attached via a 6-50 to our garage's welding receptacle. As we venture further afield, SpCs and other charging options are fewer, and so a cable dedicated to staying inside the car at all times the car is seeming more and more like a good (read: essential) idea.

    Potential solution: we have an uninstalled HPWC - likely to remain that way as long as we keep this current house - and so the topic is as in this title, ie

    What are the pitfalls of extracting the HPWC cable from its home base and affixing it to a plug? And if so, what plug would be the mose versatile for US & Canada driving?

    More specific question: what exactly would I do with the two small lines that are neither L1, L2 nor Ground?

    The more I looked at this today, the more I thought perhaps this isn't the best idea, but certainly hope FlasherZ, Cottonwood or any of the other whizbangers on this forum can persuade me otherwise....

    ???????????
     
  2. davewill

    davewill Member

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    #2 davewill, Jan 29, 2015
    Last edited: Jan 29, 2015
    Won't work at all. The car needs the electronics that are in the "base". Why wouldn't you go ahead and install the HPWC in your garage, and take the UMC with you in the car, like God and the Engineers at Tesla intended? You can fit the HPWC with a 6-50 plug and cord and set it for a 50a circuit, so you won't need to do any extra electrical work. You can even unplug it if you need to do some welding. :biggrin:
     
  3. tga

    tga Active Member

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    You can't put a plug on the end of the cable and make it work. There is electronics inside the HPWC and/or UMC that talks J1772 to the car, telling the car the max current it can draw. The car then tells the HPWC/UMC that it is connected and it's safe to turn on the power. If you try a dumb cord without the J1772 electronics, the car will never see power.

    If I were in your shoes, I'd attach 6 feet of 6/3 SOOJ cord and a 6-50 plug to the HPWC, set the DIP switches for a 50A breaker, mount it on the wall in the garage and plug it in. Then store the UMC and your adapter collection in the car.

    Edit: Darn. Second.
     
  4. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    +3 and agree with the two posters above.

    The car won't use the power unless it can talk J1772 with something. A cord won't do that.
     
  5. miimura

    miimura Active Member

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    Put a cord with a 6-50 plug on the HPWC and mount it to the wall after setting it to 40A. Keep the UMC in the car.
     
  6. Saghost

    Saghost Active Member

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    As the other said, you can't pull the cord off of the HPWC and expect it to work. In theory you could put the entire HPWC on a cord, though - but AFAIK in the US the largest outlet in common use is the NEMA 14-50, which only provides half the power an HPWC is capable of, and I'm not sure there's a way to tell the HPWC it doesn't have full power available. You could of course turn down the charge current in the car to match. I'd think it makes more sense to use the HPWC at home, either hard wired or on a 6-50 cord/plug and keep the UMC in the car, though.

    The other thing you could do is buy another EVSE for either role - either through Tesla or a J1772 unit and use the provided adapter. Clipper creek sells a number of units with plugs as well as hard wired and has a great reputation among the other EV sites.
     
  7. tga

    tga Active Member

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    There is a set of DIP switches that allows you to configure the max current advertised on the pilot signal to match the HPWC's circuit. 50A breaker/40A charge is one of the settings.
     
  8. wk057

    wk057 Senior Tinkerer

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    #8 wk057, Jan 29, 2015
    Last edited: Jan 29, 2015
    Just taking the cable from the HPWC without the unit will get you nowhere.

    The HPWC unit as a whole will indeed work if you put a 240V plug on it. Just be sure to set the DIP switches properly. I've done this and had a 14-50 male plug on the HPWC before.

    HOWEVER... the catch is that this is illegal per the NEC.

    NEC 625.13 - Electric vehicle supply equipment rated at 125 volts, single phase, 15 or 20 amperes or part of a system identified and listed as suitable for the purpose meeting the requirements of 625.18, 625.19, and 625.29 shall be permitted to be cord-and-plug-connected. All other electric vehicle supply equipment shall be permanently connected and fastened in place.

    Since the HPWC is not designed or listed for use with a plug and cord setup, and is not 125V/20A or less, it would violate the NEC to put a plug on it. So, while in my opinion it is perfectly safe to do so if done properly (proper gauge wire, proper setting of the DIP switches, etc), do so at your own risk. If anything were to happen where insurance would come into play this would be a code violation.

    The UMC, on the other hand, is listed for plug-and-cord connectivity.
     
  9. AudubonB

    AudubonB Mild-mannered Moderator Lord Vetinari*

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    Geez...sure is a good thing I used "...or horrible?" in my thread's title!:scared:

    Thanks, everyone. I'll likely try the HPWC-into-a-6/50 method, as suggested. And hope this thread is useful for others, too.
     

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