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is there a way for the car/charger to adapt to incoming current availability?

Discussion in 'Model S: Battery & Charging' started by ljwobker, Oct 18, 2013.

  1. ljwobker

    ljwobker Geek.

    Nov 30, 2012
    Raleigh, NC
    Is there some way for the car to be told what level of current can be drawn on any given charging circuit? I ask because (for my Nissan LEAF, I, hiss...) I have a modified EVSE and a number of pigtail power cords that will allow me to plug into various 20, 30, and 50A receptables. Now, in the LEAF it doesn't matter because my model year only charges at 240x/16A/~3.3KW -- so no matter what I plug it into it's not going to over draw the circuit. In an MS, that's a whole different story. If you're plugging into a commercial EVSE, the signalling protocol negotiates the current that both sides agree on... but how does that work if you're just using the mobile charger? Is there a way to explicitly "dial in" the current on the mobile charger itself? That seems high-risk for someone getting it wrong and tripping a breaker. Or does the mobile charger absolutely *Require* the use of the Tesla brand adapters, and the adapters themselves are keyed to tell the charger how much power is available? (This seems like the only thing that could meet electrical codes/compliance?)
  2. AmpedRealtor

    AmpedRealtor Well-Known Member

    Jun 30, 2013
    Buckeye, AZ
    See above bold, that is your answer. Also, if you change the charging current using the setting in the car (for instance, you want to reduce your NEMA 14-50 charge from 40A to 15A for whatever reason) the car will remember that setting based on your GPS location. For all of the adapters included with Model S and built by Tesla, charging is pretty much a transparent plug-it-and-forget-it solution.
  3. yobigd20

    yobigd20 Well-Known Member

    Oct 28, 2012
    Skaneateles, NY
    I thought the Model S takes in whatever it is supplied and that the "way it is controlled/capped" so that the breaker isn't tripped is simply a different resister size in each adapter. I think there's been a few threads on here from electrical engineers that have taken apart the adapters and swapped the resisters to pull a different amount (aka I think this was done a long time ago to take advatage of 20amp sockets instead of being capped at 15amps).
  4. Puyallup Bill

    Puyallup Bill Member

    Sep 7, 2012
    Puyallup WA
    No boo, hiss here. We like our LEAF.

    I am limited to 12 Amps, 240 volts in the garage, so I use the Tesla supplied 14-50 adapter and dial down. If I need more, I move out of the garage and plug into a 40 Amp electric stove outlet (don't ask) and dial up from 12 Amps to 32 Amps.

    The garage and outdoor parking space are close enough that the GPS thinks they are the same, and when I forget to dial down again, you got it - pop.
  5. Cosmacelf

    Cosmacelf Well-Known Member

    Mar 6, 2013
    San Diego
    Yes, each Tesla adapter (for NEMA 5-20, 14-30, etc.) communicates with the car to tell it the maximum current draw for its type of plug. So it is plug and forget.

    In addition, you might have situations where you still want lower than 80% of maximum current, so you can manually dial down current draw on the car screen as well.

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