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HPWC vs. 14-50 NEMA and need for dual charger?

Discussion in 'Model S' started by klnenrgfan, Aug 14, 2018.

  1. klnenrgfan

    klnenrgfan New Member

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    I currently have a 240volt NEMA 14-50 that I had installed to spec for my first Model S P85D with dual chargers and currently use the mobile connector. I just received a HPWC that I would like to have installed and have just received a used Model S P100D to replace the P85D.

    Does anyone know if there is new wiring or other significant work that is needed to place the HPWC in the location of the NEMA 14-50 240V system? Is it just a matter of changing the amps in the circuit breaker area (e.g. increase to a 100 amp circuit breaker)?

    I looked at configuring a new 2018 S and they now longer offer dual chargers so I am not sure on the 2017 if it matters or not. But assuming it does, with a single charger only, will I benefit from using the HPWC or will a single charger only set up limit the speed of the charge with the HPWC set up. I am assuming in the P85D charger the only real benefit of the dual charger was at the superchargers but I am not sure.

    Thanks for your input.
     
  2. bishoppeak

    bishoppeak Member

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    Don't up the amps for your HPWC unless the wiring can handle it(at least 4 gauge) the new single chargers can handle 72 amps continuous, so you'd need at least a 90 amp circuit for that. Dual chargers only came into play for AC charging, not the DC superchargers.
     
  3. KJD

    KJD Supporting Member

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    Why not just charge the P100D the same way you did the first car. You can use the mobile connector and just plug it into the NEMA 14-50 outlet. No changes needed.

    You need to look at the size of wire used. If they used wire sized for the 50 amp breaker( 6 awg for example) , then no you can not just change the breaker. You would need to buy new wire heavy enough to match the 100 amp breaker.
    Ampacity Charts

    That it not how it works. The superchargers bypass the on board charger in the car. The supercharger sends DC current directly to the battery pack.
     
  4. JohnnyG

    JohnnyG Weee!

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    #4 JohnnyG, Aug 14, 2018
    Last edited: Aug 14, 2018
    1. You can install the HPWC in place of your current NEMA 14-50R and just configure the HPWC via internal jumpers to charge at a max rate of 40A.

    2. If you want to charge at the P100D's max rate (72A), you'll need a 90A circuit.
    • This means that you'll need to verify that the wire gage is at least 3AWG (the new HPWC manual suggests 2AWG).
    • Your 240V breaker is a 90A or 100A.
    • An electrician (or qualified personnel) has done a load assessment of your supply line and box to verify you can handle the extra load.
    3. Nose cone cars (pre refresh) came with either one 40A charger or two (totaling 80A). The P100D comes with a single 72A charger. You can benefit from an HPWC.

    4. The onboard chargers are only used for Level 1 & Level 2 charging (AC charging). Level 3 charging (DC charging), such as at a Supercharger, bypasses the onboard chargers. So it doesn't matter what you have for an onboard charger when Level 3 charging.
     
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  5. tstafford

    tstafford Supporting Member

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    OP - FWIW I’m faced with the same situation and I’m just electing to continue to use the NEMA and the UMC. Not worth the hassle to upgrade all the electricals as I’ve never had a charging time issue at my house.
     
  6. JohnnyG

    JohnnyG Weee!

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    Just a reminder, all cars shipped since ~12/2017 now come with a UMC that is limited to 32A. This is most likely sufficient for most, but just wanted to toss that out there as a point of consideration.
     
  7. tstafford

    tstafford Supporting Member

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    Yeah. It's still an overnight charge. But good point.
     
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  8. klnenrgfan

    klnenrgfan New Member

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    All great points everyone. Doesn't sound like there are many advantages to installing the HPWC at home and it could come with considerable cost based on the current wire gauge. Changing out the amp may be cheaper. I will have the electrician take a look at it when he is out doing some other work for me. Thanks again.
     
  9. tpham07

    tpham07 Active Member

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    a wall connector (it hasn't been called HPWC in 2 years) only needs 3 wires vs the 4 a NEMA 14-50 uses, so its actually easier to wire.

    You can rip the outlet out and use the same breaker/wiring to charge up to 40A. Not much advantage of that though vs just using the UMC.
     
  10. whitex

    whitex Active Member

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    Where did you see it? I just wired a new one in (old Gen 1 was not compatible with 2018 car) and the manual said AWG3 or whatever the code says. I used AWG but it barely fit the HPWC terminals. Where did you see suggested AWG2? I got another HWPC coming (whenever Elon gets around to signing it ;) - waiting for months now) and thinking really hard whether AWG2 is overkill. AWG3 would be easier to work with, especially given that AWG2 copper takes a lot of effort to squeeze into the HPWC terminals.
     
  11. murphyS90D

    murphyS90D Member

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    It depends on how long the wire run is. Also AWG 2 is much easier to find than AWG 3 is. My run is 73 feet long and is wired with AWG 2 in conduit. Make sure that the wire, at both ends, has a copper ferrule installed to provide a solid surface to clamp down on. It is difficult, if not impossible, to clamp all of the strands if a ferrule is not used. If any strands are not clamped that becomes a higher resistance point and it will get hotter than it should. AWG 2 with a ferrule will fit but it is not easy due to the stiffness of the wire. The ferrule is not just slid onto the wire. It must be crimped with the proper crimper to form a solid block of copper.
     
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  12. bob_p

    bob_p Active Member

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    Based on the experience with our 2012 S P85 (dual chargers), 2017 S 100D (48A charger) and 2018 X 100D (72A charger), 32A of charging should be enough to support overnight charging.

    We have an HPWC connected to a 100A circuit - that is now used to charge our S 100D @ 48A. And our X 100D is connected using Tesla's 14-50 connector to a 14-50 outlet. We also tried charging our X 100D using the 32A UMC2. And for overnight charging, all of these options work.

    For anyone that needs to install power for S/X charging, I'd recommend using a 14-50 outlet, and not incur the additional expense required to support an HPWC at the full 72-80A charging rate. You really don't need to charge that quickly, at least not for overnight charging.

    We now have a 2nd HPWC (the referral award on our X 100D), and we're debating what to do with it. We could get a 14-50 cable for it and install it connected to the 14-50 outlet. But there really isn't any benefit for doing that, other than looking cool...

    And for Model 3 owners, with the smaller battery packs - it's even easier to charge overnight using just a UMC2 or the 14-50 connector with a 14-50 outlet.
     
  13. JohnnyG

    JohnnyG Weee!

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    Albeit, my experience was before the new cheaper 2nd generation UMC, I found a huge advantage to having the HPWC, even if just connected to a 50A circuit.

    When I first got my car, I was traveling nearly 150 miles per day and every weekend traveling to family that was 225 miles away. While at my family's place, I was traveling nearly 120 miles per day, and not near a SuC. I left my UMC plugged in at home, because I needed it nightly, and then had to remember to grab it Friday morning to bring with me to my family's place, as I needed it nightly there on weekends. After the 2nd time I forgot my cable in a rush, I decided I wanted to leave a cable in my trunk, and have a cable I left in my garage.

    At that time, a UMC cost the same as an HPWC. It seemed foolish not to get the HPWC. It gave me more flexibility for the future, and a cleaner install for the here & now. I just removed my 14-50R, and replaced it with the HPWC. This way I could leave my UMC in the car for use while traveling. This has been one of the best moves I made.

    Like others, I chose not to incur the extra cost to increase my 50A circuit to a 100A circuit. I would have also had to purchase the secondary charger for the car to have had made use of it.

    At this point, with the cheaper UMC, it might make more sense for someone to just get a UMC to have a second one to keep in the car, unless they want more flexibility for the future.
     
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  14. JohnnyG

    JohnnyG Weee!

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    If you're going to piggy back the new HPWC to your current one in your garage (I assume that's a short run), the 3AWG should be plenty.
    I really apologize, I don't remember were I found the info on the 2AWG. It may have had to do with the average length being longer than 50ft. Let me dig around and see where it was...
     
  15. whitex

    whitex Active Member

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    No need to apologize. :) I was just curious where it said AWG2, given the difficulties I had fitting AWG2 copper wire into HPWC terminals. I was quietly hoping they made the terminals bigger very recently, since I still have one HPWC coming to me.
     
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  16. JohnnyG

    JohnnyG Weee!

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    Thanks man! :) I did find the reference in the manual I was referring to... It can be found here, on page 19, subheading 2, second paragraph.

    This is the excerpt:
    Screen Shot 2018-09-19 at 2.56.02 PM.png

    In full disclosure.... This manual is listed on Tesla's site, and states it is for North America, 80A, Single Phase Installs, however, it is not the same manual that they link to from the shopping page for the HPWC. That manual states 3AWG. :confused:
     
  17. whitex

    whitex Active Member

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    You gave me hope thinking maybe the top connection bracket has bigger terminals. My next HPWC will be my 1st with top entry. I went and looked at the top entry low profile bracket leftover from the last install but no, the terminals look the same or maybe even smaller :( The Tesla supplied wires running from the bracket terminal to actual HPWC are AWG4, so they fit just fine. I think I'll do my run with AWG2 and worse case scenario cut a few strands off to fit the terminal block- that will still give me a nice low impedance path and only drop down to terminal size at the bracket. It won't matter since Tesla uses AWG4 from that terminal anyways.
     
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  18. murphyS90D

    murphyS90D Member

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    Crimp copper ferrules on the ends of the stranded wire and they will fit. Cutting off strands will increase the resistance of the connection which will result in heat generation at the connection.
     
  19. whitex

    whitex Active Member

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    The ferrule adds even more size. Tesla's wires have them, and they fit, but they are AWG4. Since Tesla is going out of the terminal block with only AWG4, there will be increased resistance already at the terminal block.
     
  20. SSedan

    SSedan Member

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    IMO a circuit larger than 50amps with a wall connector is a reasonable step looking to the future. Suspect most of us will eventually own a different EV than the one we have what will it accept?, and real potential for multiple later, prepare to load share today.


    Even if you don't want to buy a second wall connector later installing one on a 60amp breaker today can let you charge at 48amps and swap the cable to the second car before bed.

    At least consider the future when wiring things up. Maybe you have capacity maybe not but think about it.
     
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