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Charging at 208v

Discussion in 'Charging Standards and Infrastructure' started by siatacars, Jul 15, 2013.

  1. siatacars

    siatacars New Member

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    I want to instal a NEMA 14-50 receptacle for our TESLA visitors. We have 208v. Is there a problem with that?

    Paul Toti
    Jericho Canyon Vineyard
    Calistoga ,CA
     
  2. scaesare

    scaesare Active Member

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    Nope. Will just be a tad slower.
     
  3. Eberhard

    Eberhard #421 Model S #S32

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    why not using an 3-phase european style charger, will triple your charging speed. But works at monophase as well. 3x30A at 3-phases or 80A at monophase both is possible.

    best

    Eberhard
     
  4. Doug_G

    Doug_G Lead Moderator

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    Because North American cars can't accept 3-phase.

    scaesare is right, NEMA 14-50 is just fine, but the car will charge 15%-20% slower than if it were 240 volts. Not a big deal.
     
  5. siatacars

    siatacars New Member

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    We do have 3-phase. I will look for a European charger unless you have a link.

    Thanks,
    Paul
     
  6. Bipo

    Bipo Member

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    3-phase won't work with American cars... If you want to provide 240 V you can install a little transformer. It might be inexpensive (less than $1,000 including socket and installation). Or you can install a HPWC or a J1772 Level 2 (up to 70 A).
     
  7. siatacars

    siatacars New Member

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    Thanks Bipo
     
  8. Cosmacelf

    Cosmacelf Active Member

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    It isn't unusual to have 208v chargers. Many if not most public J1772 chargers operate at 208v since they are attached to commercial wiring, and not residential wiring. The cheapest thing to do is to provide a Nema 14-50 receptacle. That's what I installed in my commercial location. If you're up for spending more money, the next step up is to buy a J1772 charger. Get at least a 60 amp version, the more the merrier. Dual charger equipped Tesla's will be able to use whatever higher current you have.
     
  9. Pmacafee

    Pmacafee Member

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    Take a look at the equipment from Clippercreek, they are the manufacturers of the HPWC and have a HPWC equivalent unit with a J-1772 connector that will have the benefits of a HPWC and I think will still charge other kinds of vehicles. The CS-100 is around $2,100 and the HPWC is $1,200 from Tesla.

    http://www.clippercreek.com/products.html

    Philip Macafee
     
  10. scaesare

    scaesare Active Member

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    If you are suggesting installing a transformer to plug in to a 208V socket to convert it up to 240V... that won't buy you anything, as power remains a product of the voltage and the current. Thus, if you transform the voltage up, the available current will drop, resulting in the same amount of pwer (wattage) available to the car. (Actually slightly less due to losses).

    If you are suggesting replacing the building's line transformer (from a Delta to a Y for instance), that is likely to be FAR more expensive than you suggest...
     
  11. TonyWilliams

    TonyWilliams Active Member

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    Well, of course there can be an advantage if done properly.

    If we want 40 amps at 250 volts (10kW), then a step up transformer that pulls 50 amps at 208 volts (10.4kW) will do the job, with transformer losses included.

    Pretty simple.
     
  12. Bipo

    Bipo Member

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    That's it. The Model S charger is rated in Amps, not in Watts. So if you plug it to a 40A-240V will obviously get more power than from a 40A-208V. That's why I suggested that ;)
     
  13. brianman

    brianman Burrito Founder

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    There is not a problem with it, and it will save at least one person from the nightmare that is replenishing an empty battery on 110V/12A. Thank you for your generosity.
     
  14. siatacars

    siatacars New Member

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    We have already had to use buck/boost transformers for solving some of our pump problems. I don't think it is practical in this case. I'm just looking to instal the most practical feature for our occasional TESLA visitors.

    Paul
     
  15. scaesare

    scaesare Active Member

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    The reason I asked if he was "suggesting installing a transformer to plug in to a 208V socket to convert it up to 240V" is because it's not what you are describing.

    Again, power delivered is a constant. Why go to all the trouble of installing a transformer to convert a a 208v/50a circuit to 250v/40a?

    Just run a new circuit with a 60amp breaker (or better yet 100a) and be done with it, assuming you have HPWC, J1772 EVSE, or the like... if not purchasing one to hardwire is still likely to be cheaper, easier, and more convenient( keep your UMC in the trunk).
     
  16. Monto

    Monto Member

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    I agree, just put the 14-50 in. Very inexpensive and will get the job done at 8kW. I have that at the airport and it works fine. Just the fact that he wants to do this for his visitors is enough for me. No reason to over engineer the solution.
     
  17. deonb

    deonb Active Member

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    Current is drawn, not proffered. You can't change "available current" by doing anything at the source.

    Of course if the source is behind a 50A 208V breaker, it will trip before you reach 40A at 240V, but there was no mention of the breaker size on the circuit.
     
  18. pete8314

    pete8314 Vendor

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    As I recently found out, the 14-50 I have here at work is running on 208v, so this is more or less the charge rate you'll get:

    photo1.PNG

    (I have another screenshot showing the amps at 40/40, so I'm not sure why that varies).
     
  19. TonyWilliams

    TonyWilliams Active Member

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    Because a single charger 40 amp car can use 10kW. Again, there can be an advantage if done properly.

    I'm not suggesting that the OP do this, as it was a response to a different post. Just hang a Clipper Creek CS100 on there with a 100 amp breaker and 3 gauge wires.
     
  20. scaesare

    scaesare Active Member

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    Agreed, current is drawn, but as you mention it's limited at the breaker. If you have a larger supply available, spending your money on a EVSE that can do 70-80 amps will give you more bang for your buck. If you are limited by a 50 amp circuit, a transformer isn't going to buy you anything.
     

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