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Wall Connector or 240V Outlet

Discussion in 'Model S: Battery & Charging' started by rsr70, Feb 14, 2016.

  1. rsr70

    rsr70 Member

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    In the final stages of convincing the DW that a Tesla 90D is a reasonable purchase. :smile:

    My question, in calculating additional costs, how many of you have installed the Wall Connector at home versus a 240V outlet?
     
  2. Steve2498

    Steve2498 Member

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    Either will work fine. With a NEMA 14-50 240V plug, you'll Need to use the cable from the car, which works fine but some prefer the convince of leaving that in the car. If that's the case you'll need to either buy a second UMC or for an extra $100 get the wall charger. Then of course there's the question of how many amps do you want to charge with? If more than 40A you must have the wall charger (as well as a second on board charger for the car). The more flexibility you want/need, the more you will spend.
     
  3. .andrew

    .andrew Member

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    We have a NEMA 14-50 outlet and it is sufficient to charge both of our Teslas back to 90% each night. We both have a commute of about 80 miles round trip.
     
  4. Branzo90D

    Branzo90D Salt and Pepper

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    I have a NEMA 14-50 as well. It easily charges the car overnight at about 40A. You really can only use the power of the HPWC if you have dual chargers installed.
     
  5. rsr70

    rsr70 Member

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    Thank you all! As I guessed. The NEMA 14-50 will be sufficient for my driving.
     
  6. CHG-ON

    CHG-ON Still in love after all these miles

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    240 14-50 works fine for me. What does DW mean? Should I ask?
     
  7. ernies

    ernies Member

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    I am going to guess: DW = DEAR WIFE....
     
  8. Vince Cobelo

    Vince Cobelo Member

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    The wall connector is far more elegant and I like keeping the portable cable in the car not having to worry about wrapping it up and tucking it away.

    The difference in price and cost of installation isn't all that much different and remember you can deduct the cost of equipment and installation on your Federal Income Taxes (Or so it has been said here on the forum. I have yet to do mine yet but we'll see.) I had my wall connector installed with 80/100 service just in case I wanted to add the second charger to the car which I doubt that I'll do but its there and that cost is negligible. Just be sure to set the dip switches to 40 amps if you go that route.
     
  9. ArtInCT

    ArtInCT Always Learning

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    I have both the 14-50 on a 50A circuit breaker and the HPWC on a 100A circuit breaker. Went with the "high availability" solution so if the UMC or the HPWC craps I have a backup.
    Also my barn is on Plugshare so this setup makes sharing a bit more universal to other EV'ers in need.
     
  10. rsr70

    rsr70 Member

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    You are correct. :)
     
  11. jbcarioca

    jbcarioca Active Member

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    FWIW, I find that I actually reduce the amperage I draw at home because I always have overnight, and want to allow for about 110 miles driving with 30% reserve so I charge to 70-75% generally. I find I can get that with a 5 amp charge and 12 hours, if I expect less I increase to 10 amp. Other things being equal, keeping the charge going for longer decreases stress on the 12v and eliminates phantom drop. Thus, were I to revisit the issue I'd be quite happy with 208v/30a, but I would still want a Tesla connector to eliminate the hassle of adapters.
     
  12. TexasEV

    TexasEV Active Member

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    But other things are not equal. Charging at such low amperage is much less efficient. You're wasting electricity.
     
  13. efusco

    efusco Moderator - Model S & X forums

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    This is my philosophy as well. I like to avoid the wear and tear on the less durable UMC and just keep it in my car at all times. You could buy a second UMC (one for the car, one for the garage), but The cost difference is minimal b/w the UMC and HPWC. If the wiring will handle it, it's nice to have the additional option of higher amperage charging.
     
  14. freeewilly

    freeewilly Member

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    +1 on NEMA 14-50 240V plug.
    Just in case you purchase other EVs that use J1772 charger in the future.
     
  15. Gremlin

    Gremlin Member

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    I went with the NEMA 14-50 wall outlet. My electrical box was in the garage, only cost me 750 bucks. Had I gone the wall until route, probably 1500 bucks. Not like I drive 100 miles a day, but I do drive 71 miles a day which is why I have 36K on a 18 month Tesla. :- (
     
  16. StaceyS

    StaceyS Member

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    I went with NEMA 14-50. Two of them, actually, as I'm planning ahead for a 2nd EV.

    After using a 20 amp 120v outlet for months, I figured out that with our driving habits (very low daily mileage), the full 80 amp HPWC really isn't necessary for us. Even if I have to travel outside town and come home with an empty battery, the car is charged back up sometime in the early morning (2 or 3am) on our NEMA 14-50.

    Also, if you don't have dual chargers, the HPWC provides no charging advantage, other than being able to keep the UMC in the car.
     
  17. jborak

    jborak Member

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    My family just installed a 250v 50A Nema 14-50 socket in their garage, so I can charge when I visit them, and I used it for the first time last night with a UMC and it worked perfectly! I was getting 31 miles/hr. They had their electrician install a lever that can be used to cut the power off in any emergency without having to fuss with the socket. The wall mount would be nice. In case you have a mix of EVs in the future you can try some other EV charging stations (EVSE), I think Bosch makes some nice ones you can buy on Amazon, may be cheaper than the Tesla HPWC.
     
  18. Vince Cobelo

    Vince Cobelo Member

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    I think the strongest argument for going with a 14-50 rather than Tesla's wall connector is if you foresee a EV in your future not necessarily compatible with the UMC. But even then it is likely you would sell your UMC along with the Tesla when it is time to get rid of it. Really you can't go far wrong either way. Just if you have a garage more showroom rather than storage room then the UMC is prettier. That and if you foresee wanting to go to the second charger in the MS.
     
  19. jbcarioca

    jbcarioca Active Member

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    It seems many, if not most, people are confused about this. There is no inherent difference in efficiency between 120v or 240v. There is enormous difference depending on how the electric is sourced and transmitted. As everyone knows the hight the voltage the lower the amperage required for a given load. However, properly wired, there is no measurable difference based on the amperage drawn. The exception is that higher amperage creates higher residence and is thus less efficient than is lower amperage. One major reason for higher voltage is to reduce amperage, thus decrease transmission losses.

    In a typical home connection there is no discernible difference in transmission efficient except for a modest decrease in efficiency as average load rises beyond a certain point. That point can be easily observed thermally because it is power lost to heat. If the cord is warm it is operating less efficiently than if it is cool. Thus with a properly connected and powered HPWC 80amp charge will less less efficient than will 10 amp charge.

    Let's be serious. The difference in efficiency whatever it is, is far outweighed by actors of convenience. It will be quite hard to measure material increased cost for any given amperage choice in a properly designed system.

    If anybody cares there are exhaustive studies of relative efficient of different options. This one I just used for a reference on long distance power transmission for a utility:Electric power transmission - Wikipedia, the free encyclopedia
     
  20. Rocky_H

    Rocky_H Member

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    Well, you’re partially right, but are still confusing things. You are correct that it’s not about the voltage exactly, but when people refer to those, they are comparing a NEMA 5-15 outlet, which is providing 1.4 kW to the car, versus something like a NEMA 14-50, which is providing about 9.6 kW. The power level definitely does contribute to an efficiency difference, because there is a decent level of overhead power being consumed by running the charging system. I think it’s around 400 W or so, so it’s about 1/3 of the power of the 120V wall outlet is being lost just going to running the charging circuit. That is why going to a 5-20 adapter makes such a difference if you have to use a wall outlet. It’s increasing the current from 12A to 16A, so a 33% increase in power, but the amount of energy getting into the car’s battery is a lot faster than 33% increase, because the overhead is already covered, so all the extra is going into the battery, rather than being partially lost.

    So what you are referring to is at the high power levels, where loss from resistance in the wiring is the main thing that could be hurting efficiency, but it seems you were not considering about at really low power levels, where resistive losses are negligible, but the dominant factor is wasting a lot of energy from keeping the charging circuit running much longer than it needs to.
     

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