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Home charging setup question

Discussion in 'North America' started by ModelNforNerd, Jan 30, 2017.

  1. ModelNforNerd

    ModelNforNerd Active Member

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    I'm awaiting my Model 3, and thought my charging situation was all set. (townhouse, 1 car garage, 200A service...I was just going to put in a 50A breaker to charge my Model 3 at 40A load....)


    But now the wife wants to move to a house with a yard. We've picked the house, which was built in 1900, but is almost done being completely renovated.

    So now my charging situation will be: house with 100A service, no garage, gas appliances (which will reduce the load on the 100A box....)


    I'm leaning towards the HPWC, since it will only be "live" once it's in the car and at it's set time....best to not have a live wire hanging off the side of the house.....but can I get away with a 50A breaker, and charge at 40A overnight when load is lowest? Or should I spring for 200A upgrade and put in an 80A breaker for the HPWC?

    The wiring to the outlets around the house should not require any upgrades, as the entire house except foundation and studs is brand new....I'd have to obviously pay for a 200A box, and about a 15 ft run to the outside wall.

    Fun twist: the home was converted from oil heat to natural gas during the renovation. Instead of cutting another hole in the wall, I am going to ask the electrician to run my HPWC cable through the capped-off oil fill tube still sticking out of the side of the house. :cool:


    Clearly I have until at least this fall to even get mildly worried about this....but having an idea of what I want to do ahead of time wouldn't hurt.
     
  2. Craig-Tx

    Craig-Tx Member

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    The HPWC can be installed on just about any breaker you desire. There is an internal switch that you dial in to specify the size of the circuit that the HPWC is installed on. This will tell the vehicle when charging to limit to XX amps based on the size of the circuit.

    For example, if your house can only support adding a 35 Amp breaker, and that speed of charging would adequately support your driving needs, you would dial the rotary switch on the HPWC to "5", which would limit the charging current to 28A.

    35A was picked arbitrarily to emphasize that even many non-common breaker sizes are supported.

    The HPWC install instruction are available on the Tesla website. Page 21 shows the table of the rotary options.

    Honestly, if your house can support a 50 A circuit, I'd go with that for the time being. If you find that you need faster charging, you can always upgrade the house service and wiring to the HPWC at a later date. (Assuming the Model 3 will even charge at higher currents.)
     
    • Informative x 1
  3. ModelNforNerd

    ModelNforNerd Active Member

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    Thanks. I kinda figured I could "dial back" the HPWC. Just wondering if, should the need arise to charge during the day, would the 40A load on the 50A breaker stress my 100A service too much, or would I be ok..?
     
  4. MorrisonHiker

    MorrisonHiker S 90D 2017.34 2448cfc

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    How many miles do you drive per day? Charging at 40 amps is probably fine for most people.
     
  5. aesculus

    aesculus Still Trying to Figure this All Out

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    See if you can install a 200 amp panel. It will depend on the feed in wires. They may be big enough. Then you can dedicate 100 amps to the house and 100 amps to the car. An electrician can tell you quickly if the feed in wires could accommodate the 200 amp setup.
     
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  6. ModelNforNerd

    ModelNforNerd Active Member

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    Honestly, probably not going to be much. The reason the wife is making us move is so we're in walking distance to the train. So now I'm probably only going to be driving a total of less than 20 miles M-F.

    There's always the possibility of me transferring to another agency (I work for the gov't), which could mean I'd be back to commuting in the car again instead of mass transit.
     
  7. ModelNforNerd

    ModelNforNerd Active Member

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    I'm sure they can accommodate a 200A feed.


    Other, newer houses in the neighborhood run 200A. ALL of the wiring inside this house has been redone to 2016/2017 code, so really it would just be the expense of a new breaker panel, new breaker for the HPWC, and the line for the HPWC.
     
  8. Lloyd

    Lloyd Well-Known Member

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    40 amps is more than you need. Your car will charge for less than an hour every night.
     
  9. ModelNforNerd

    ModelNforNerd Active Member

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    True, for now....but I'd like to "future-proof" myself.

    My wife may also want a "city car" EV at some point, too. Maybe a used Leaf or something.
     
  10. aesculus

    aesculus Still Trying to Figure this All Out

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    That stuff is just a few hundred dollars if that. It's always the labor, access and something like the feed in wires, transformer that make the project expand into the thousands.
     
  11. Rocky_H

    Rocky_H Active Member

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    There are places online where you can do a residential load calculation. It figures in basic outlet and lighting loads by square footage. And then it figures in any of the bigger electrical loads like a stove, air conditioner, and clothes dryer. Then, you can also use the "non coincident load" provision, where the circuit for charging the car will be used mainly at night, not at the same time as the dryer/stove, etc. so it does not have to count against that same total. You mentioned gas appliances, so I'm assuming that means gas for dryer, stove, water heater, and furnace, but A/C is probably electric, right? So yeah, I would think you should be able to have a 40 or 50 amp breaker fit into a 100A total service pretty well. Or you could eventually split that up with two electric cars, like with a 20/20 or 20/30. Charging rates would be fine for 8 hours overnight kind of thing.
     
  12. ModelNforNerd

    ModelNforNerd Active Member

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    Yes, all brand new, so hopefully efficient, ie less draw.

    And I'd really only need to "range charge" once every few months. I'd usually know well in advance and could time it accordingly. I live close enough to Superchargers where if I had to go on a long trip on short notice, I could just burn through Supercharger credits to get a full charge.

    The tricky part will be down the road if the wife decides she wants an EV. Then I'd probably upgrade to 200A.
     
  13. MorrisonHiker

    MorrisonHiker S 90D 2017.34 2448cfc

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    The new HPWCs can communicate with each other and balance the load. While it would be slower if both cars were charging at the same time, you could still run both of them off a 50 amp breaker. Alternatively, you could schedule the cars to charge at different times during the night.
     
  14. ModelNforNerd

    ModelNforNerd Active Member

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    It's likely the wife goes with a non-Tesla EV. Does the HPWC talk to EVSEs?

    It's also possible she gets a "dumb" outlet, in which case, it would be up to us (or the in-car setups) to schedule charging.
     
  15. MorrisonHiker

    MorrisonHiker S 90D 2017.34 2448cfc

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    Good point. We only have Tesla EVs in the garage...but the point about scheduling charging could still work. You could get the cable changed on the HPWC or install a non-Tesla EVSE and then use the J1772 adapter with the Tesla. There are also some EVSEs that have multiple cables but they are still quite rare. It's probably cheaper to just focus on the one Tesla for now and figure out what you need to do later when/if you get a second EV.
     
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  16. Rocky_H

    Rocky_H Active Member

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    It's good to already realize this. I see some people on here who talk about needing high amp charger in the car and wall connector with a 100A breaker because of some dire emergency that may come up once a decade where you get back from a long road trip and need a quick turnaround to see your dying aunt's poodle (or aunt's dying poodle?) on her deathbed, so you need the highest amp charging possible, just in case etc. etc. But, what backup plans do you have? I, like you, do have a Supercharger fairly close, so if I needed faster charging than overnight, I can easily go do that.
    No, that's only for Tesla wall connectors to talk with each other, not to other brands of devices.
    This could still work OK on a 100A total house feed if one of the cars is not doing a lot of miles. Some people get by just fine with a Nissan Leaf on a regular 120V 15A outlet for all of their charging. If you can put in a J1772 wall connector on a 240V 15A circuit, that's twice as fast charging, and would still do really well for a short range electric car and wouldn't even push the total amps much on your 100A main panel.
     
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  17. JHuberman

    JHuberman Member

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    We have a Volt and a MS60. The volt has a 220v 30A circuit with J1772 connection. I installed an HPWC with a 60 amp breaker. It is working out very well.
     
  18. wiredprairie

    wiredprairie Member

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    Personally, I'd do 2 things:

    1) Not worry about it until Model 3 deliveries begin in earnest (and maybe wait until you've been notified that you need to specify the configuration).
    Then, when #1 is true, upgrade your home's electrical service to 200A and buy the then current HPWC (as it's OK for it to be in the elements).

    That way, you wouldn't need to worry about using too many amps at any point in the day (like an air conditioner, toasters, space heaters, electric pressure cookers, etc.) and you won't have to worry about how you'd make a standard NEMA 14-50 outlet safe for outdoor use.
     
  19. Lloyd

    Lloyd Well-Known Member

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    #19 Lloyd, Jan 30, 2017
    Last edited: Jan 30, 2017
    I have a1600 sq foot condo in San Diego and installed a 14-50 plug for charging. The condo has 100 amp service. I found that I could charge the car at 40 amps, run the air conditioning, lights and tv without issue. Washer and dryer was ok also! I had to schedule the charging to not conflict with the electric cooking.
     
  20. ModelNforNerd

    ModelNforNerd Active Member

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    I also want to see if the tax credit for EV infrastructure installs makes it into the 2017 tax year....but I'm not going to hold my breath on that. It could be argued that upgrading the house to 200A was necessary to safely install the HPWC......

    ;)
     

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