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NEMA 14-50 with 120v

Discussion in 'Model S: Battery & Charging' started by AndreyATC, Feb 12, 2014.

  1. AndreyATC

    AndreyATC Member

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    Hello all
    I'm looking to install outdoor charging receptacle in my summer home
    I only have 120v line coming in, so that leaves me limited options
    At first i was thinking NEMA 5-20 to get at least 20amps, but that's not much win over 5-15

    The main question is, will NEMA 14-50 work with 120v?
    I know you can wire it with just one "hot" to be 120v instead of 240v
    But will my MS take the charge if it's 120v?
     
  2. markb1

    markb1 Active Member

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    You're talking about plugging the UMC into a NEMA 14-50 that has one hot disconnected? No, that won't work. The UMC 14-50 adapter doesn't use the neutral pin at all, so the circuit will not be complete.

    What do you mean you only have 120V coming in? That's really odd.
     
  3. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    You would be better off changing the circuit breaker to a 20A 240V breaker and changing the outlet to a 6-20R. This uses the same wires with the same rating (I assume that you have #12 at least), but changes the service and outlet to 20A at 240V. The three wires will now be L-L-G for 240V instead of the original L-N-G for 120V. Now you can make or buy a 6-20P to 6-50R pigtail adapter and use the Tesla 6-50 adapter. To avoid popping the circuit breaker, you will have to program the MS to 16 Amps maximum for this location. After you do all of that, you should get 10-11 MPH charge rate which is way better than the 3 MPH you would get from the 5-15 outlet.

    Good Luck!
     
  4. AndreyATC

    AndreyATC Member

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    Mark
    NEMA 14-50 has 2 hot, 1 neutral and 1 ground
    How is this not complete circuit?
    NEMA 14-50 designed to be either 120v or 240v
    The question is if Tesla is smart enough to charge from NEMA 14-50 at 120v

    File:NEMA simplified pins.svg - Wikipedia, the free encyclopedia

    - - - Updated - - -

    Guys,
    I can only have 120V
    240v is not an option there
    I'm looking to get maximum charge possible from 120v line
     
  5. markb1

    markb1 Active Member

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    It's not a complete circuit because the NEMA 14-50 adapter, which comes with the car, has no internal connection on the neutral pin. It's wired to complete a circuit from hot to hot. If one hot is disconnected in the outlet, there will be no circuit.

    - - - Updated - - -

    I'd like to understand how you have house that only has 120V coming into it.
     
  6. bluetinc

    bluetinc Member

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    The quick answer to you is, even if you made the car believe that it can charge at 80A on 120V, the car itself limits charging on 120V to 20A. The best you can do with the adapters that Tesla sells is 16A at 120V. Could you go into more detail why the home only has 120V available?


    Cottonwood,

    I like this idea, but instead of using the 6-50 Adapter and then trusting the software to always correctly limit (which it may not do when it sees a failure, as we have seen), you can make a custom 6-20 to 5-20R CUSTOM TESLA ONLY adapter, and then use Tesla's own 5-20 UMC adapter, it will pass the 240V along and set the current limit to 16A.


     
  7. AndreyATC

    AndreyATC Member

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    #7 AndreyATC, Feb 12, 2014
    Last edited: Feb 12, 2014
    I dont really need 80A @120v, 30-40 would be plenty
    I thought the car would automatically use 40A draw when it senses NEMA 14-50
    But because it's only 120v, it'll give me 4.8kw charge instead of 9.6 on 240v
    House is in gated community and they are all wired with 120V.
    Outside breaker with 50A limit to the house

    So, what can i do with only 120v available to me?
    Anything higher than 20A?
     
  8. bluetinc

    bluetinc Member

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    No, the very best you could do is 20A at 120V. The car senses the 120V and even when it is told that it can go higher, it will not.

    Is your house particularly old? I've simply never know a power company to send 120V out of their distribution transformers. The normal distribution is to send every house 240V, which is centered around ground, so each leg is 120V. Houses can then (if they want) simply use each leg (and the neutral return) and wire everything inside the house at 120V, even though there is 240V available inside the main panel.

    Peter

     
  9. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    Ah, I now understand. To get the maximum charge rate, you need 240V. If you are willing to do advanced electrical stuff, here is a path.

    If you have enough 120V current, you can use an auto-transformer like this one, Outback Power Inc. - Integration Hardware Autotransformer, for about $400 to step up the 120V to 240 V. This Outback unit is rated for up to 25 Amps, so should be good for 20A continuous. I use one of these with a 120V backup generator to get 240V.

    If you have capacity for a 50A, 120 circuit breaker, you can feed this transformer with that. 25A passes through without going through the transformer for one line side and 25A gets reflected through the auto-transformer to make the other line side. The 120V, single phase, 50A circuit is converted to a 240V split-phase, 25A circuit. From that you can pull 20A continuous, for a 14 MPH charge rate. I would just wire this to a 14-30, that is dialed back from 24A to 20A in the MS.

    Figure 5 on page 9 of http://www.outbackpower.com/downloads/documents/autotransformer/manual.pdf shows a wiring diagram. Just follow the generator Black/White (120V, single phase) to the Red/Black/White (240V, split phase) path to the inverters. For you the Generator would be replaced with your 120V, 50A circuit, and you would feed the 14-30 with the Red/Black/White wired going to the inverters.
     
  10. efxjim

    efxjim Member

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    Wire in a tt-30r so you meet code.
    Leviton 7313 30 Amp, 125 Volt, NEMA Tt-30R, 2P, 3W, Flush Mounting Receptacle, Straight Blade, Industrial Grade, Grounding, For Recreational Vehicles, Side Wired, Steel Strap, Black - Amazon.com
    Then use an adaptor that connects the hot and the neutral from the tt-30R and connect it to the 14-50's hot legs. And connect up the grounds of course. Label it for EV charging only. The car will then sense 120v and will allow a 20a draw for the fastest charge allowable on 120.
     
  11. mitch672

    mitch672 Active Member

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    Call an electrician, odds are you can get a 240V circuit installed.

    Or charge at work/use public chargers, or a nearby SuperCharger.
    In winter, 120V charging is painfully slow, to the point of being useless.
     
  12. samcarney

    samcarney Sam C

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    AndreyATC, The Roadster adapters use an internal diode that depending on the orientation will direct the pilot signal to limit current. I charge with my emergency generator during power failures with an L14-30 adapter plugged into the 120v 30amp receptacle.
    Model S adapters may use something similar. 001.JPG
     
  13. AndreyATC

    AndreyATC Member

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    Please read the thread
    I cannot get 240
    This is remote vacation place with single 50A 120V line coming from the street to the house
    No electrician would be able to help or even allowed to mess with community wiring

    I do have 14-50 installed at home and charging daily at 40A

    - - - Updated - - -

    So, without using generator
    I can make any receptacle from 120V 30A breaker
    What would be my next step?
    Use this?
    Shop Tesla Gear Roadster High Power Wall Connector to Model S Adapter
    Or i misunderstood you
     
  14. liuping

    liuping Active Member

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    This is definitely the best way to go.

    evseadapter.com makes a NEMA TT-30P RV Plug to 14-50R Adapter wired like this: http://evseadapters.com/adapters-for-tesla-model-s.php.
     
  15. mitch672

    mitch672 Active Member

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    The external breaker must go to an interior distribution panel. You have opened it, and examined it in detail?
    I'm not aware of any jurisdication that would allow just a 120V feed to a residence, even in a vacation home.
    also, if it is comming in directly from the street, where is the meter?
     
  16. AndreyATC

    AndreyATC Member

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    Meter is outside the house after the street breaker
    Not sure where the main panel is, but it's probably a few hundred yards away
    Every other home in the community is the same way

    If 240V was even slightest possibility, i'd pursue it, but unfortunately i'm limited to 120v with 50A max
    BTW, i had to buy 120v outdoor hot tub because no 240 is possible

    - - - Updated - - -

    This is great!
    20 is definitely better than 12 or 16A, gives me 7mph charge
    I just wish MS could pull 30A from it instead
     
  17. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    With my transformer idea, you could use a 120V, 30A breaker to feed the transformer and get a 240V, 15A circuit. The most you could draw reliably (no breaker pops) would be 12A. It's a lot of hassle, but 12A at 240V is equivalent to 24A at 120, and a 20% increase in charge rate over 20A at 120V.

    Good Luck!
     
  18. AndreyATC

    AndreyATC Member

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    Thank you
    Good option as well
    Close to $400 for upconversion and extra 4 amps
    I'm not sure if it's worth it
     
  19. Cottonwood

    Cottonwood Roadster#433, Model S#S37

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    I agree!

    If you trusted managing all the other loads, you could put in a 40A breaker and get the equivalent of 32A, 16A at 240V. You would just have to be very conscious of other loads and not go over 40A total on your 50A panel. Now, if you got a Tesla Energy storage unit to store up a bunch of kW-hr when you are away... :wink:
     
  20. AlMc

    AlMc 'Senior Moments' member

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    Another alternative: Would the community allow use of a generator? Noisy and you are using gas (seems to defeat purpose of an EV I know) but if this is a vacation home that you spend little time at but need to make sure you can get your S charged???
     

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