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Nema 14-50 vs HPWC pro's and con's

Discussion in 'Canada' started by hemants, Dec 21, 2014.

  1. hemants

    hemants Member

    Dec 13, 2014
    Nema : seems fast "enough" for overnight charging, only issue is you will likely end up leaving the mobile charging cable at home - is this a big deal?

    HPWC : more pricey but 50% rebate in Ontario on parts and labour narrows the gap, faster charging (if you come home for lunch and go out again). You can leave mobile cable in car for flexibility.

  2. jgs

    jgs Active Member

    Oct 28, 2014
    Ann Arbor, Michigan
    How many public charging points require the mobile charger? Around here AFAIK all of them are J1772, which only requires the adapter, not the charger. My local friend with a Model S says he leaves his mobile charger at home except when he's on road trips, and keeps the J1772 adapter in his car. Others have made similar remarks. Accordingly, I installed a NEMA 14-50 in my garage preparatory to getting my MS. I did ask when it was going in, and the cost increase for a HPWC configured to charge at full rate would have been substantial -- it's not just the cost of the unit, it's the cost to install the 80A wiring and service (or actually, 100A to support a constant 80A load, if I recall correctly). For my situation, it was possible to use existing conduit for the 50A 14-50, but the 100A HPWC would have required a new trench out to my garage, a prohibitive cost for something I almost certainly don't need.
  3. Doug_G

    Doug_G Lead Moderator

    Apr 2, 2010
    Ottawa, Canada
    NEMA 14-50 is definitely fast enough for overnight charging.

    I usually use my UMC for charging at home. And yes, I usually drive around without it in the car. You don't want to be constantly plugging and unplugging it because it will wear out the NEMA socket. It's not designed for that sort of use.

    These days I rarely use the UMC when on road trips. Most on-the-road charging I do is on J1772. I do take it along if I'm visiting my brother-in-law because he has a NEMA for me in his garage.

    I also have a Roadster HPC at home, which I have adapted to J1772 so I can charge either car at 70A with it. I've only ever used it to charge the Model S three times, and I think I only actually needed the faster charging once (I needed to run some errands shortly after returning home from a road trip). So I really only "needed" faster charging once in two years (Essie had her second birthday yesterday).
  4. dasRad

    dasRad Member

    Nov 25, 2013
    Kelowna, BC, Canada
    #4 dasRad, Dec 21, 2014
    Last edited: Dec 21, 2014
    The UMC running at 40 A has worked great for us over the last year. Never needed to charge faster than 40A at home in that time period and I very seldom take the charger with us. On longer trips I carry the UMC, but we've never needed it away from home.

    Having said that, I would prefer the permanent installation of a HPWC with its heavier gauge cable, but I would still run it at 40A. A year ago the HPWC was $1200 and it didn't make sense as I only had 50A available in our panel, so $1200 for no faster charging made no sense to me. At the current price of $750 (no rebate in BC at the moment), I've considered picking up an HPWC, but I really don't need it. Now, at $400, I would "need" it.
  5. yobigd20

    yobigd20 Well-Known Member

    Oct 28, 2012
    Skaneateles, NY
    So I have 62k miles on my P85 now over the last 20 months. I have a NEMA 14-50 installed and a HPWC that still sitting in its box. So after 62k miles there still hasn't been a single instance where I needed the 80A over the 40A. Hence the reason it's still sitting in the box. The 40A is way more than enough even for high mileage drivers like myself. To the average 15k/yr or less driver even 40A is overkill.
  6. jerry33

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

    Mar 8, 2012
    The big reasons for using the HPWC are:

    1. A faster charge--if you actually need it.

    2. The heavier duty cable.

    3. The longer cable.

    4. More weatherproof than the UMC.

    5. It should be more efficient because of the heavier gauge wire and the lack of a receptacle/plug connection and UMC adapter connection.

    6. Because there is no receptacle/plug connection, there's no concern about the tightness of the wires in the receptacle, the state of the receptacle, or the adapter connection on the UMC.

    7. The UMC can be kept permanently in the car.

    8. If you already have one or the other, having a second provide redundancy.

    All but the first advantage are valid whether you set the UMC at 40 amps or at 80 amps.

    Note that if you set the UMC to charge at 50 amps and have twin chargers, each charger will charge at 25 amps. This may increase the life of the chargers (speculation).
  7. shelbri

    shelbri Member

    May 27, 2014
    Sandy Hook, CT
    UMC is perfect for overnight charging. In addition to the extra cost of a HPWC and the wiring associated, I believe you also need a dual charger onboard to take advantage of greater than 40a charging. Unnecessary IMHO. If anything, buy an extra UMC if you feel you need to having something in the car for road trips. I take mine with me on road trips to VT where I have another 14-50 plug available.
  8. wayner

    wayner Active Member

    Oct 29, 2014
    What's the price diff between the two? A P85D with all of the options costs about $140k. Is it worth cheaping out to save a few hun or so (after rebate) on the installation of a charger?
  9. purplewalt

    purplewalt Active Member

    Jun 9, 2013
    Dallas, Texas
    The higher wattage required for the HPWC might require a certified electrician to install an electrical sub-panel.
    The HPWC by itself is ($750).
    If you decide to get the HPWC, your car should probably be ordered with dual chargers ($1,500), because the second charger could be added later, but it is expensive ($3,600) after you take delivery.
    Note: Single or Dual chargers have no impact at a Supercharger, as that is DC power and it goes straight to the batteries (it does not pass through the chargers).
    Unless you are driving over 220 miles a day, the UMC will give your MS all the charge for the next day you require while you sleep @ night.
  10. JST

    JST Active Member

    May 23, 2013
    You don't need to run the HPWC at 80 amps. You can run it at 40 instead.

    Now that the price has come down, I am seriously considering it, since I like the permanence and the other pluses mentioned above. But if I did it I would run it at 40 amps since I have a single charger in the car.
  11. spentan

    spentan Active Member

    Dec 26, 2012
    I live in a condo (with attached garage, finally, living in an apartment without home charging was terrible),

    I just had my HPWC (which I got with my prior Model S for free/included) installed last week.

    As my power supply is 100A, I got the HPWC put on a 50A Breaker. (I presume this means it'll charge at 40A).

    I do have the dual chargers on my soon to be delivered P85D, but I guess I won't be able to use it (unless if it splits the load, 20/20).

    The HPWC is pretty intense, cable and such is nice and durable, and tbh, I prefer it to the UMC. Also this allows my UMC to sit in my car, in case its required at a location with NEMA 14-50 or a normal 110v.
  12. ZBB

    ZBB Emperor

    Feb 27, 2013
    As others have said, the UMC is fast enough for most of us...

    In in my case, I'm at 29k miles in just over 18 months (most miles I've ever put on a car that fast). My commute is ~60 miles and I "only" have a single charger. That means the UMC via 14-50 takes ~2 hours to top back up each night.

    My UMC stays in the garage, and is only unplugged for visits to the service center or a road trip. Even on our 4k+ road trip last summer, the UMC was only plugged in a couple times -- and only at 120V. All of those could have been avoided also -- for example the first was overnight at a hotel, and the ~30 miles gained overnight were really not necessary. The rest were while visiting my in-laws, and I could have left the car down at their local J1772 charger instead.

    Similar to JST, now that the HPWC is lower priced, I'm considering getting one. It would be nice to have a more permanent install, but I think I'd rather spend the $750 on something else...
  13. liuping

    liuping Active Member

    Jul 23, 2013
    San Diego
    It's not really "cheating out". For many people ere is no need at all, so In those cases getting a HPWC could be consider throwing away $1000 to $2000 (installation can be a lot more costly). I know several people who have no problem spending large amounts of money on things they feel have value, be loth to waste any money on thing that don't.

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