TMC is an independent, primarily volunteer organization that relies on ad revenue to cover its operating costs. Please consider whitelisting TMC on your ad blocker or making a Paypal contribution here: paypal.me/SupportTMC

Acceptable extension cords for the UMC

Discussion in 'Model S: Battery & Charging' started by timdorr, Dec 24, 2012.

  1. timdorr

    timdorr Model S P1698 / VIN 1657

    Joined:
    Aug 2, 2012
    Messages:
    449
    Location:
    Atlanta, Georgia, United States
    So, the official line from Tesla is that you should never use an extension cord with the UMC. However, I find the length somewhat limiting and was hoping to throw an extension cord in the trunk to act as a life line to emergency charge on a 110v outlet. Does anyone have any experience using the UMC on an extension cord? What sort of gauge and length limits have you run into? I've heard the UMC or car can detect when you're using an extension cord, but that's likely based on voltage fluctuations and will undetectable with a high enough quality of cord. I'm hoping to find one that I can use unofficially :)
     
  2. sublimaze1

    sublimaze1 8Dec2012 / Leeroy Jenkins

    Joined:
    Sep 6, 2012
    Messages:
    1,092
    Location:
    Basin City, TX
    I believe it has been discussed and rendered as such:

    Tesla officially states "no extension cords"

    But,

    If you have a sufficient ga. wire, and correctly attached extension receptacle, you should be okay. Consulting someone with such experience is recommended. After all, RVs use extension cords all the time and, Unless you are Cousin Eddie, things go very well most of the time.
     
  3. shokunin

    shokunin P85 & S40

    Joined:
    Feb 28, 2012
    Messages:
    960
    Location:
    Irvine, CA
    It's possible the UMC can measure the resistance and impedance of the cable to determine if there is an extension cable (undersized) and potentially throw an error. Otherwise for 120v 20a/15a, i'd go for a 10 awg cable, and don't keep it coiled while charging as that will generate additional heat.
     
  4. mcornwell

    mcornwell Active Member

    Joined:
    Dec 20, 2010
    Messages:
    1,016
    Location:
    USA
    I had ordered a 50A extension cord from Amazon last week, and my mailman said he dropped it off on the porch Saturday, but I never saw the box, nor did my wife. :-( The mailman also remarked that he remembered dropping it off, as he saw the old HP Laserjet 4+ that I had put out for someone who claimed it off my Craigslist "free stuff" post. Me thinks the jack hole who took the printer may have taken the box with my extension cable. Grrr....

    As soon as I get a replacement I'll add a data point for those who might want a slightly longer 240V option.
     
  5. FlasherZ

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

    Joined:
    Jun 21, 2012
    Messages:
    7,019
    It depends upon the length of the cord, the distance from the outlet you're using to the panel, and the current you'll be charging at.

    For 120V, to keep the voltage drop within range, you can use a 14 AWG cord if your TOTAL one-way circuit length from the car to the breaker panel is < 50 ft., 12 AWG if your total is < 100 ft., and you'd need to go to 10 AWG if you're at 150 ft. or greater.

    For 40A @ 240V (NEMA 14-50), you should use #6, and your total one-way circuit length can be 300 ft, with voltage drop at reasonable levels.

    For 24A @ 240V (NEMA 14-30), AWG 10 is good to 200 ft. one-way from breaker panel to the car, go one gauge up (AWG 8) if you need more.

    As mentioned, keep your cord to the smallest length possible.
     
  6. Psullivan

    Psullivan Member

    Joined:
    Sep 30, 2012
    Messages:
    30
    Location:
    Carlsbad, CA
    Mike,

    Let me know if you want to come by and charge until your cord comes.

    Pat
     
  7. wycolo

    wycolo Active Member

    Joined:
    May 16, 2012
    Messages:
    2,425
    Location:
    WY
    ModelS arrives home with 16 miles remaining, down from the 271 @ Tesla Shop after a ~245 trip. So need to charge right away. Tractor is in the way so used an old medium duty 50ft extension cord. S shows 112v 12A. Charged ok for 1 1/2 days but then just stopped. Moulded plug on old extension had been running 'warm'. Replaced with 'new' heavy duty ext cord (50ft?) which now shows 117/118v 15A. Charging resumes but still at 2miles per hour rate.
    --
     
  8. efusco

    efusco Moderator - Model S & X forums

    Joined:
    Mar 29, 2009
    Messages:
    4,592
    Location:
    Nixa, Missouri, United States
    I purchased the 30' 6Ga version of the Amazon cord linked above ( Camco RV 55195 50 Amp 30 Extension Cord with Handle : Amazon.com : Automotive ).

    Just tried it out (finally after having it almost a week!) and it seems to work just fine. I put it in range mode (since it was full in standard) and it is pulling 40amps/10kW without any problem or warnings or anything. It is a very heavy duty cord for RVs, at least as high a gauge as in the wall wiring. I don't intend to use this a lot, but if I need to reach an outlet that's been "ice'd" or that is further away than the UMC will reach it could be a live saver.

    2012-12-25 11.19.01.jpg 2012-12-25 11.19.23.jpg

    I'll let it charge for an hour or so and report back if anything untowards happens.
     
  9. timdorr

    timdorr Model S P1698 / VIN 1657

    Joined:
    Aug 2, 2012
    Messages:
    449
    Location:
    Atlanta, Georgia, United States
    Thanks for that info. Very informative and exactly what I was looking for :)
     
  10. Raven

    Raven Member

    Joined:
    Oct 9, 2012
    Messages:
    258
    Location:
    US
    How long is Tesla's stock charge cord?
     
  11. efusco

    efusco Moderator - Model S & X forums

    Joined:
    Mar 29, 2009
    Messages:
    4,592
    Location:
    Nixa, Missouri, United States
    18' for the UMC
    25' for the HPWC
     
  12. FlasherZ

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

    Joined:
    Jun 21, 2012
    Messages:
    7,019
    No problem. Just remember this is one way from the BREAKER PANEL, not just the receptacle. :)
     
  13. mcornwell

    mcornwell Active Member

    Joined:
    Dec 20, 2010
    Messages:
    1,016
    Location:
    USA
    Thanks Pat. I can charge fine if I pull in straight, but prefer to back-in to the garage, so doing that today.

    Amazon was awesome, and overnighted a replacement extension cord today, no questions asked.

     
  14. Robert.Boston

    Robert.Boston Model S VIN P01536

    Joined:
    Oct 7, 2011
    Messages:
    7,842
    Location:
    Portland, Maine, USA
    As another data point, I am using a NU-CORD 50' extension cord (NEMA 14-50) to charge at 40A without issue. It's 6/3 + 8/1 copper.
     
  15. Puyallup Bill

    Puyallup Bill Member

    Joined:
    Sep 7, 2012
    Messages:
    606
    Location:
    Puyallup WA
    Good to hear, as I will be using the same cord, but 36', and at 30 Amps.
     
  16. mcornwell

    mcornwell Active Member

    Joined:
    Dec 20, 2010
    Messages:
    1,016
    Location:
    USA
    My Camco 50A extension cord works fine. I believe there is a 1-2 volt drop, from 242 to 240-241, but that could have just been related to the time of day when I tested it. The downside is the cord is THICK, probably twice as much as the UMC.
     
  17. Plug Me In

    Plug Me In Member

    Joined:
    Nov 29, 2012
    Messages:
    580
    Location:
    Central Virginia
    Thinking ahead to visits to my Mom's house about 180 miles away from mine. I don't know why I'm trying to save money at this point, but I'll be charging most likely from my Mom's dryer outlet and instead of buying $100 adapter from Tesla, I'm thinking of getting an adapter for the 14-50 plug from an RV site. Anybody tried this? I'm concerned there may be significant voltage drop across two adapters.
     
  18. FlasherZ

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

    Joined:
    Jun 21, 2012
    Messages:
    7,019
    See the FAQ thread for information on why you might want to avoid this.
     
  19. Plug Me In

    Plug Me In Member

    Joined:
    Nov 29, 2012
    Messages:
    580
    Location:
    Central Virginia
    Thanks Flasher. I was unaware of that excellent resource you put together. I'll probably just buy the Tesla adapter rather than go through all the gymnastics.
     
  20. giants2001

    giants2001 Member

    Joined:
    Dec 13, 2012
    Messages:
    70
    Location:
    san jose

Share This Page