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How does timed charging work on the model 3?

Discussion in 'Model 3: Battery & Charging' started by matto, Aug 28, 2018.

  1. matto

    matto Member

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    I have cheaper electricity between the hours of midnight and 7am. Can I program the car to charge only between those hours? And if it's not done by 7am, stop and automatically continue the next night?
     
  2. dhrivnak

    dhrivnak Active Member

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    Mostly. You can set the timer to start at midnight and you will be finished by 7 if you have a 240v outlet.
     
  3. Rocky_H

    Rocky_H Active Member

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    Right. You can set the start time. And it is basically unheard of in most situations that the car could possibly take more than 7 hours to charge. And if it ever does, oh well--it's a few bucks.
     
  4. matto

    matto Member

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    No, that was exactly the question I'm asking. I want to know if it will stop at a certain time. It sounds like it cannot.

    I am considering using an existing 30 amp outlet that would take more than 7 hours to charge depending how much I drove.

    If it keeps going it's not the end of the world. I'm just trying to understand what the software supports before making my wiring decisions.
     
  5. Big Dog

    Big Dog Member

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    SW does not (yet?) support a stop time. But you can back calculate it and then adjust the % charge to finish by ~7 am (assuming that gives you enuf juice for your daily commute)..
     
    • Informative x 1
  6. matto

    matto Member

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    Gotcha... Thanks Big Dog.
     
  7. MikeATL

    MikeATL Member

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    Do I understand correctly that the last 10% requires more energy than the first 10%? hence you don't really want to be charging to 100% unless you've got a long drive the next day?
     
  8. Big Dog

    Big Dog Member

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    ^^more energy, no. But it is slower. In other words, the charging slows down --- same electrons (aka 'energy'), but they go in slower to reduce heat.
     
  9. MikeATL

    MikeATL Member

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    OK, so it's a cost issue only if you're going to run over your nightly discounted electric rates (if you're on such a plan.) ... Thanks!
     
  10. Rocky_H

    Rocky_H Active Member

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    Ah, well, that's a possibility. I see on Tesla's site they list for a 30A circuit, supplying 24A, that the Model 3 would get about 22 miles per hour, so 154 miles in 7 hours. So it's not a "set it and forget it" thing, where you can just permanently set an end time, but I guess you could turn down your limit to about 70% or something on a particular day that you drove it down really low.
    Hold on--what you're saying isn't all that accurate in this context. People think of the slowing charging speed at Superchargers, where it goes down from 115kW to 80 to 50 to 30 to 20, etc. That tapering curve applies all the time, but remember what this charging power is on a home 30A dryer outlet. This is less than 6kW power. It's already so far below the tapering curve that you would never be able to see that getting slowed until it's up to about 98%+ full. So for home charging, the answer is generally no, they won't see any slowing until the very last percent or two.
     
    • Like x 1
  11. forkee

    forkee Member

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    There are apps that connect to the car and allow you to set stop time and other customized things
     
  12. compu85

    compu85 Supporting Member

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    That sucks :/ Having a cutoff time is really critical for those of us on time of use power, since something running past even once will screw up the electric rate for the entire month. Good thing our JuiceBox has this!

    Our ELR supports start times, stop times, and "be charged by" times!

    -J
     
  13. vikefan

    vikefan Member

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    I would highly suggest you install a NEMA 14-50 outlet to speed up the charge time. You won't have to worry about the car continuing to charge after your timed rate increase in the morning, and honestly installing one is pretty straight forward if you have even the most basic understanding of how electricals work.

    If you have zero understanding of how wiring a socket would work, then obviously call an electrician, but even then, the installation would only be maybe $500. Definitely worth it IMO to have a car that charges up in a few hours vs. an entire 24 hr period.
     
  14. matto

    matto Member

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    My first quote for a 50amp outlet was $2400 for the because it requires running a 110 feet of 100amp cable from the other end of the house. :eek:

    There's already a 30 amp breaker in the garage I can use for a Nema 14-30.

    I'm tempted to do the 50 anyway, but it's a lot more money and requires cutting into multiple walls. :(

    Oh? Do you have any specific suggestions?
     
  15. Big Dog

    Big Dog Member

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    if you do pull a cable, recommend that you future proof it by running heavier gauge wire so that you can easily add a 60 amp circuit and HPWC in the future.
     
  16. matto

    matto Member

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    How big would you do?
     
  17. TT97

    TT97 Active Member

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    TeslaFi will let you schedule charge stops.
     
  18. vikefan

    vikefan Member

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    Oh, well that’s crazy then. My electrician wanted $450, but the breaker was just on the other side of the wall from where the socket was going to be. I’m amazed the price would be so dramatically different just because he has to fish some walls. That’s really not that difficult ..
     

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