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Taking advantage of 72 amp Charger

Discussion in 'Charging Standards and Infrastructure' started by gmgtex, Jan 3, 2016.

  1. gmgtex

    gmgtex Member

    Dec 22, 2015
    Austin TX
    I have a Sig X vin # 3xx soon to be delivered hopefully. My electrician installed a Nema 14-50 per Tesla website and I did not realize the Sig X came with a 72 amp charger and why that made a difference. To upgrade to take advantage of 72 amp charger I am being told I need to scrap the Nema 14-50 install new 100 amp fuse install new conduit and need wall charger to take advantage of 72 amp charger at home for $3k. I already paid $2k for the Nema 14-50 and have not even used it yet.

    Does 72 amp charger help at all with Nema 14-50? Do I need a wall charger to take advantage of 72amp charger? Must I replace Nema 14-50 to take advantage of 72 amp charger?
  2. miamibeacher

    miamibeacher Member

    Nov 23, 2015
    Miami Beach
    Well, from my non-expertise, the 14-50 only allows 40a continuous charging on a 50a breaker. To fully take advantage of the 72a charger in the X, you'll have to upgrade the wires and the fuse/breaker. You will also have to purchase the HPWC, because the cable that comes with the car is only suitable for 40a, just like your 14-50.

    You'll also have to ask yourself if it's necessary at home to use all 72a to charge. Most people charge over night daily, so whether it takes 3 hours or 5 hours, doesn't matter. You'll still be able to charge at some locations which have higher than 40a AC output.
  3. dhrivnak

    dhrivnak Active Member

    Jan 8, 2011
    NE Tennessee
    #3 dhrivnak, Jan 3, 2016
    Last edited: Jan 3, 2016
    While my Roadster can charge faster, 99% of my home charging is at 40 amps. I just do not need to charge faster at home. The 40 amps are easier on the wiring, cooling system and power company.
  4. linkster

    linkster Member

    Apr 22, 2013
    #4 linkster, Jan 3, 2016
    Last edited: Jan 3, 2016

    I would suggest you give the NEMA 14-50 a go for a while with your beautiful new incoming X before shelling out more $. We have a 75-80 mile round trip commute and can still almost sneak by with our TOU 4hr "window" with a 14-30 (can't believe it has been discontinued :mad:) charging @24A (18mi/hr. charge rate) for 3 years and 60,000 miles.

    Your 72A charger will still come in very handy at the many >48A Tesla destination charging locations.

    Enjoy your new X!! :biggrin:
  5. idoco

    idoco Member

    May 7, 2013
    Outside Philly
    Unless you are regularly travelling 200+ miles, coming home for less than six hours, and leaving again for another 200+ mile trip, the NEMA 14-50 will be fine. I would venture a guess that the majority of people with dual chargers in their Model-S charge at less than full amperage capability when at home.

    The main advantage of the 72amp charger is for quick turnaround at destination charging when available.
  6. Tedkidd

    Tedkidd Member

    Dec 8, 2013
    Rochester, New York, United States
    Do you have time of use rates? If so, is the window for cheap electricity only 4 hours?

    Do you plan to get another electric car?

    My aunt and uncle had dual chargers on their first car - didn't use them once. After a while they stopped charging every day. Their new car doesn't have dual chargers.

    I have a Smart EV. I charge on 110. There is maybe one time since I've owned it that I wished I had 220 at home. At 40a, you are charging 6-7x faster...

    Now when I do run a line to my garage it'll be 200a so it's somewhat futureproofed. I think designing for "what you need now" when it comes to infrastructure upgrades in rapidly changing tech is poorly thought through.

    Designs not rushed tend to be designs with least regret. Chart the potential permutations of your future situation now, then if you do need to make a $3000 change in a year or two, you won't have to do it AGAIN a year or two after that.
  7. ohmman

    ohmman Maximum Plaid Member

    Feb 13, 2014
    North Bay, CA
    Good advice here. Live with it for a while, and see if you need to upgrade. It's already installed. I doubt you'll need it - the 72A charger will be useful for destination charging. At home, 40A should get you by just fine.
  8. patrick40363

    patrick40363 Member

    Mar 25, 2014
    Why did it cost you $2K for a 14 50 install?
  9. Kandiru

    Kandiru Member

    Oct 20, 2014
    What Ohmman said.

    If you are a small town professional or spook needing to make frequent runs in the middle of the night
    you may need a HPWC.

    Otherwise the NEMA 14-50 is just fine. After all the car will spend all night in the garage. Some also
    claim that long term the lower charge rate is gentler on battery storage degradation.
  10. DavidM

    DavidM P2624, Delivered

    Aug 18, 2011
    I used the UMC with my Model S for nearly 3 years on my 14-50 outlet. Charging at 40A continuous was more than adequate 99% of the time. But after the first year, Tesla rolled out the 5.8.4 firmware update which caused my connection to continuously back off and only charge at 30A. For nearly 2 years I was not happy with that charging rate. I finally decided to abandon my 14-50 circuit. I purchased a HPWC for $750 and paid $500 for labor to install an 80A circuit for it. Now I can continuously charge at 64A, which is 47 miles of range per hour. By the way, IMO the HPWC is a much safer way to charge, with a hard wire connector and heftier conduit.

    I took a 7,200 mile road trip in my Model S and really enjoyed using many of the Tesla Destination Charging Stations (which are 40A to 80A). So even if you don't upgrade to a HPWC at home right away, you'll still be able to take advantage of the Destination chargers, as well as the superchargers.
  11. Rocky_H

    Rocky_H Member

    Feb 19, 2015
    Boise, ID
    I also don't see any need for more than 40A for charging at home, but it can sometimes be handy when out on a trip.
  12. BrokerDon

    BrokerDon Member

    Aug 23, 2014
    Newport Coast, CA
    We received a Tesla HPWC with our "inventory" 2015 P85D with dual chargers last July. Now that we've had it for 6 months I agree with the consensus above: Use your 14-50 for a while and see if you really NEED a HPWC for your home charging. From my experience we've only needed to charge higher than the 14-50's 40A charge limit ONCE in 6 months... When I'd forgotten to plug in our Tesla when I got home. The HPWC 80A charge rate allowed me to get a full charge in the short time I had that morning before I left on a trip.

    The only other advantage of having a HPWC is we leave our Tesla charge cable in our car all the time since the HPWC has its own cable. Definitely more convenient than unstowing / stowing the Tesla charge cable every time we charge at night. Buying a 2nd charge cable would solve this inconvenience but that cost would pay for a good part of a HPWC.

    Oh and the HPWC green pulsing charging light is really cool... especially since our garage has a window. :cool:

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