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50 amp subpanel- can volt and model S both charge?

Discussion in 'Model S: Battery & Charging' started by epares, Jul 8, 2012.

  1. epares

    epares Member

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    Hello ! this is my second post, but have a question that I havent seen an answer to yet...
    I have a 50 amp subpanel in my garage and have charged my volt via my coloumb charger with j1772 plug drawing 3.3 kwh. If I install a 14-50 nema plug in the garage as well, will the model s trip the breaker? or will it adjust its draw to accomadate only being able to pull 50 amps total? I could always use the j 1772 adapter that comes with the model s and plug the volt in 110v edison plug. what combination would be best? Not sure on this one... any help greatly appreciated!.. thanks... E
     
  2. Robert.Boston

    Robert.Boston Model S VIN P01536

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    You won't have to worry about this because once you have your Model S, your Volt won't get any driving time. :wink:

    But seriously: On the Roadster, you can dial down the charging current to avoid overloading a circuit. Seems likely that the Model S will have a similar feature. Install the NEMA 14-50; you'll want more than 3.3kW for charging the Model S!
     
  3. Andrew Wolfe

    Andrew Wolfe Roadster 472 - S 440

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    You can't run both off the same breaker. Not safe and not up to code.
    You actually can't even safely run them both at the same time on a 50A subpanel even with 2 breakers - although it is close. About 54A. Probably wouldn't burn your house down but definitely not up to code.
    You can safely add a NEMA 14-30 to that subpanel. That would give you 5.8KW charging and could be safely used at the same time as the current EVSA. Tesla will give you that adapter instead. That's what I would do.

    Even if the model S lets you drop the current (The wall charger does, but I don't think the mobile charger does) - it doesn't seem like a good idea to bet that the settings will always be right. A NEMA 14-30 gets you 150 miles in 6 hours.
     
  4. Rifleman

    Rifleman Now owns 2 Model S's!!!

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    running both the j1772 to the Volt, and a 14-50 to the Model S would trip the breaker. A 14-50 and the 110v charger that comes with the volt is borderline, it may or may not trip it. Depending on how long your daily commute is (and thus how long each vehicle needs to charge), you could probably get creative with programing the time to charge, and allow for the use of both j1772 and 14-50 (as long as they are programed to not charge at the same time)
     
  5. epares

    epares Member

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    Thanks for the input guys!... I dont want to take any chances, it seems like the safe way is the best way... My wife will be charging both cars also, so easy is best... The other thing that I realized is that my coloumb charger has the capability of charging up to 7.7Kwh, so I could just use the j1772 adapter on the tesla and plug the volt into a 110v outlet. That would keep me well below my total 50 amp draw.
     
  6. kevincwelch

    kevincwelch Active Member

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    Maybe consider upgrading to a 100 amp subpanel.
     
  7. dsm363

    dsm363 Roadster + Sig Model S

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    I agree. That will future proof your garage for a second EV down the road maybe.
     
  8. epares

    epares Member

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    The 100 amp panel would be best!.. it seems like just yesterday I dug the trench for the 50 amp panel!! LOL!!!
     
  9. dsm363

    dsm363 Roadster + Sig Model S

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    Sounds like you've done all the hard work already. Hopefully you can just pull whatever cable you need through the existing channel without any more significant work. Good luck. Very exciting times.
     
  10. kevincwelch

    kevincwelch Active Member

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    Most units in the garage will run with little draw: lights, garage door opener, etc. Furthermore, if you tend to run a large number of devices that draw a lot of current, one thing to remember is that your car will most likely be charging in the middle of the night.

    I figure with the 100 amp panel, if we add a Model X or a Volt or something down the line, will have more than enough current to charge our batteries.
     
  11. FlasherZ

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

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    From my post in the charging forum -- I went with 100A rather than going "light". I'm going to use the HPWC but I'm also preparing for the day I have another EV:


     
  12. mitch672

    mitch672 Active Member

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    When mine was done, it required trenching, so I had a 125A subpanel put in, it's 2 wire gauges larger (1AWG versus 3AWG copper), the Schedule 40 PVC put in was 1 1/4 anyway. That combination is rated at 1ooAmps continuous load (which is more than 2 Model S charging at the same time, as they each draw 40A continuous). It would also support the Tesla HPC, if you wanted that (80A continuous load, on a 100A breaker)

    I just changed the outlet I had (an L6-20) to a 14-50, and put the Schnieder EVSE I have also on a 14-50 (used a 50A range cord to the Schnieder J-1772 EVSE)

    Here is a nice wire sizing calculator: electrician2.com Wire Size calculator

    New 125A service work: 2011 EV work pictures by mitch672 - Photobucket

    Mitch
     
  13. strider

    strider Active Member

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    This feature is irrespective of EVSE. The EVSE only tells the car the maximum rate. You can always tell the car to charge at a lower rate. If you plug the UMC into a 14-50 it will tell the car it can charge at 40A. But you can dial it down to 32A or 24A and it will remember to always charge at that rate for that location until you change it.
     
  14. jat

    jat Member

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    I had a 100A subpanel installed in my garage before I got my LEAF, with the idea that I would need to support two EVs. The LEAF draws 20A steady-state, though it spikes at 30A at startup. I can also program the LEAF when to charge, but since it charges slower and a full charge is more important due to the smaller battery (plus I don't want my wife to get stranded - she is taking the LEAF when I get my Model S), I plan on letting it charge whenever and either program the Model S to charge later (when/if they add that ability) or just charge at 50A or similar (presumably charging slower is better for the battery as well). I will still get the HPWC so I can charge quickly if I need to, but that won't be the default.
     
  15. Al Gordon

    Al Gordon New Member

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    i am an electrician. if your charging your Volt at 3.3 kw that is only 13.75 amps at 240 volt.
    The S car can be dialed down (it would normally only draw at 40 amps even with a 50 amp feed to it) therefore dial the S car down to 30 amps which is what your typical J1772 WOULD GIVE YOU ANYWAYS.
    Install 14-50 amp outlet from this existing panel and put it on a 40 amp 2 pole breaker. No need to upgrade your panel unless your going for the S high power charger which I think is over priced anyways.
    This will save you much in the end and unless your driving times will not bear a 8 hour overnight sit , then would suffice.
     
  16. FlasherZ

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

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    In the US, you may not attach a UMC with the 14-50P adapter on it and connect it to a 14-50R attached to a 40A circuit/breaker. NEC article 625 requires that the UMC be considered a continuous load, and the circuit size must be 125% of the maximum drawn load -- hence 50A minimum.

    If your subpanel is off a 50A breaker in your service panel or another subpanel, you will not be permitted legally to run your model S charger and any other EV charger from that panel at the same time, regardless of whether it is "dialed down". You may run some other intermittent appliances via that panel (say, a refrigerator or small compressor), but your continuous load ratings cannot be more than 40A (and a 14-50P connected UMC uses up that entire rating).

    "Dialing the car down" is not a substitute for this protection, as it could revert to its original, default setting without warning.
     
  17. GSP

    GSP Member

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    Your J1772 EVSE most likely can be set up to deliver a 15 A pilot signal (this is the maximum the Volt can use) and use a 20 A breaker. That would allow a 30 A breaker for the Model S, supporting 24 A charging, which will likely be enough unless you drive long distance every day. The Tesla HPWC can be set up for 24 A, or you can use the UMC with the appropriate adapter and plug.

    GSP
     

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