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Power Sharing HPWC

Discussion in 'Model S: Battery & Charging' started by Lloyd, Apr 13, 2016.

  1. Lloyd

    Lloyd Active Member

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    #1 Lloyd, Apr 13, 2016
    Last edited: Apr 13, 2016
    Power sharing feature that allows a single circuit breaker to be connected and shared, servicing up to 4 Wall Connectors – an optimized solution for customers with multiple Tesla vehicles.

    Interestingly, with the Model S update today, Tesla upgraded the standard on-board charger from 40 amps to 48 amps – bringing it on par with the Model X’s standard charger.



    [​IMG]
    New Tesla Wall Connector
    [​IMG]
    Old Tesla Wall Connector


    The new charger is now available with a 8.5′ or 24′ cable and can be configured in 13 different circuit breaker settings, from 15 amps to 100 amps. Many houses are now equipped with 100 amps circuit breakers.

    When paired with a Model S equipped with a high amperage charger, it can charge the car at a rate of over 58 miles of range per hour.

    I would like to see the wiring diagram for this!!

    Edit attached!!
     

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  2. ITSELE

    ITSELE Member

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    Quick FYI. Your Mobile connector is cable 20' in length, Old wall connector is 25' so think hard before ordering the 8.5' cable version of this new HPWC.
     
  3. araxara

    araxara S-P85#3,218 X-90D#3,299

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    Not only does it do power sharing, but also supports 277V 3-Phase Wye connections - just as I installed my 2nd older style HPWC.
     
  4. FlasherZ

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

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    A correction: it doesn't support 3-phase. It supports a single-phase installation at 277V (L-N) of a 480V277Y three-phase connection.

    The European model supports three-phase.
     
  5. araxara

    araxara S-P85#3,218 X-90D#3,299

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    Right. It supports one leg of the 3-phase Wye. Which means I can install my buck-boost transformer at home and boost to 277V and get more power delivered. At the office we’re removing the buck-boost and wiring directly to 277V.
     
  6. FlasherZ

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

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  7. MXWing

    MXWing Member

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    I am about to install two Tesla Wall Connectors with power sharing and had a few questions:

    1 - Is the proper install method to create a junction box from the panel to junction box with 2AWG wire and a 100 amp circuit breaker?
    1a - Does the junction box break out to -each- wall connector with 2AWG wire?
    2 - How far can the slave wall connectors be away from the master wall connector?

    Thanks
     
  8. miimura

    miimura Active Member

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    The best way is for each wall connector to have its own breaker. You could put a 100A breaker in the main panel and run wire to a sub-panel close to where the wall connectors will be. Then, put a 100A breaker for each wall connector in that sub-panel. You will also have to run the low voltage communication wire between the two wall connectors. This does not have to follow the same path as the power wiring. Absent a higher or lower spec, I would assume that the low voltage wire should not be longer than 100m (330 ft). I don't think the power has a distance limitation as long as you compensate the wire gauge to avoid excessive voltage drop.
     
  9. MXWing

    MXWing Member

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    Is it necessary to have a 100A breaker for each slave wall connector? I think my electrician will charge a lot for a sub panel compared to a junction box that can feed all the wall connectors?
     
  10. brkaus

    brkaus Member

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    Sub-panels aren't that expensive and breakers run $50 each. I would think it would be easier/more standard to use a sub-panel than a junction box with splices.

    Having a breaker for each would also allow maintenance on one HPWC without killing the other.
     
  11. MXWing

    MXWing Member

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    Thank you for the reply. It makes sense. I am not very knowledgeable about electrical matters so appreciate the advice.
     
  12. MP3Mike

    MP3Mike Active Member

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    The cost of the box would be similar, and I don't think the breakers cost a whole lot more than the splicers that are necessary for that size of cable. (You can't just use wire nuts.) So it is really best to go with a small sub-panel and breakers. That way if one fails you can easily de-energize it to work on it leaving the other one still operational. (Though if the master fails you would have to change the setting on the slave to get it working again.)
     
  13. Big Virgil

    Big Virgil Member

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    It seems like having a separate breaker for each HPWC defeats the purpose of having "connected" HPWC's. Having them connected allows use of one 100 A breaker. Having two breakers is the same as two separate installations. Did I miss something?
     
  14. gutowskia

    gutowskia Member

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    One 100A breaker in the main panel. This single circuit is shared by all 'connected' HPWCs. From here this circuit feeds either a junction box with splices going to multiple HPWCs or instead a sub-pannel with multiple 100A breakers feeding multiple HPWCs. A sub-panel is used instead of the junction box and the additional breakers provide a disconnect for each HPWC. Many jurisdictions require a disconnect switch, the breakers in the sub panel serve as disconnect switches. The communications wire between the HPWCs assures that total power drawn does not overload the main 100A circuit. Hope this helps.
     
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  15. Ulmo

    Ulmo Active Member

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    It saves in two spots:
    • Dividing available electricity among multiple cars (common for multi-Tesla families). For instance, a 200 amp home service: you don't want 165 amps used by 2 Tesla's 80x2+loss), because add a dryer, a stove and a heat pump, and you're going past max, & lights out. This is typical in families with an S & X, and in the future, many more with 3 & Y. These days, 72amps x 2 = 144; still bumping up on the 200 pretty close. Shared use keeps the total under 100 amps, dividing among cars according to need.
    • Wiring cost if the HPWCs are clumped together but far from the main panel (rare, since most homes have parking near the main breaker box, but significant savings in cases where they're far apart)
    In either of these cases, logical sharing (and often physical sharing) of the circuit the way these things are intended is a win.
     
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  16. Big Virgil

    Big Virgil Member

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    Interesting. Thanks for the info.
     
  17. Rocky_H

    Rocky_H Member

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    The most obvious application of this is the destination charging program. They may want to put three our four of these wall connectors out by the parking spaces out front. Well, it might be a 200 foot run from the main panel out to near the curb. But then they could put a junction box there and split to the four wall connectors which are each about 20 feet from the junction box. That saves a lot of copper wire, versus four separate 200 foot runs back to the main box.
     
  18. MXWing

    MXWing Member

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    I think if I were to run 4 wall connectors in a more commercial setting, I would just do 4 - 100 AMP runs. The problem with one single feed is in theory, 4 cars would get 80 AMPS / 4.

    Maybe that still works for 99% of cases?
     
  19. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Wouldn't that be nice. The most I've ever seen at a destination is two, and they are often in the middle of other parking so the ICE cars encroach on the two parking spaces making the effective number of charging stalls one. Three or four power sharing HPWCs would be wonderful.
     
  20. Rocky_H

    Rocky_H Member

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    But it's generally a hotel--therefore overnight--therefore lots of time. It may be a little tight, but do the math. Let's say four cars that all need a pretty big fill up. Maybe 70 kwh each. That would be 280kwh total for the four cars. At a 20kW total feed, that would be 14 hours needed, but that is the absolute worst case with all four being used and almost empty. If any of them gets full, it dynamically allocates the power level among the others, speeding them up. So yeah, most of the time, a 100A breaker will be totally fine for 2 or 3 wall connectors, while 4 may be pushing it.
     
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