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75A OpenEVSE Testing with the Tesla Model S w/twin chargers

Discussion in 'North America' started by mitch672, Dec 16, 2012.

  1. mitch672

    mitch672 Active Member

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    #1 mitch672, Dec 16, 2012
    Last edited: Dec 16, 2012
    Ben (Cinergi) brought his Tesla Model S over this afternoon, and we tested my 75A OpenEVSE with it, it charged from about 126 miles (when he arrived) to 241 when he left, no issues, it worked perfectly, and the J-1772 connector head wasn't even warm after the test. The ITT 75A cable is built well, and must have low resistance internal connections, as we could not detect even the slightest hint of heating. Of course it would have been nice to have an IR temperature meter to take a picture of the contacts, but we didn't have one.

    Here is the Photobucket album link to the pictures:

    75A OpenEVSE Testing w-Tesla Model S pictures by mitch672 - Photobucket

    Mitch
     
  2. aronth5

    aronth5 Long Time Follower

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    Very good news. How long did it take to charge from 126 to 241 miles?
     
  3. mitch672

    mitch672 Active Member

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    Not really sure, we went to diner while it was charging, it was charging at about 42-43 miles/per hour of charge (it was already starting at about a half charge). it was less than 2 1/2 hours though, we were back within 2 1/2 hours...
     
  4. apacheguy

    apacheguy Sig 255, VIN 320

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    Is this system available for purchase or is it just in the initial testing phase?
     
  5. mitch672

    mitch672 Active Member

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    #5 mitch672, Dec 16, 2012
    Last edited: Dec 16, 2012
    It's an Opensource Google project, a Do It Yourself project, costs about $600 or so, but you have to have some skills to put one together:

    OpenEVSE project: http://code.google.com/p/open-evse/

    My 75A OpenEVSE build Wiki: http://code.google.com/p/open-evse/wiki/75AOpenEVSE

    It's not difficult to build, it just requires planning, patience and some soldering & mechanical assembly skills.
     
  6. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    #6 FlasherZ, Dec 16, 2012
    Last edited: Dec 16, 2012
    I haven't seen 220V in quite some time. You must have some fairly old electrical infrastructure in your neighborhood? 240V vs. 220V nets you about 4.5 more miles per hour of charge at 75A.

    Looks great -- perhaps you could go into business offering an HPWC alternative at $900 or so.
     
  7. mitch672

    mitch672 Active Member

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    Ben adjusted it down to 5A, it then read 238 Volts. At nearly a 75A load, the voltage does droop, I think it will droop in many electrical services. unknown how far my service is to the transformer feeding it, or what the wire size is on that run, the utilities have their own standards for that, as they are running in "open air". If it becomes a problem, I can have them investigate, could be they need to replace the overhead feeder to the house (which they are responsible for in MA) or upgrade the transformer.

    I will lend assistance and advice to people, but I am not looking to start a new OpenEVSE business.
     
  8. yobigd20

    yobigd20 Well-Known Member

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    +1 for AVB on the Radio ;) How does the bass sound? I can't wait to cruise to AVB and Markus Schulz every day once I get my S.
     
  9. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    You shouldn't see that much of a voltage drop across the range of load, that's pretty significant (7.5%). It's certainly outside recommended guidelines (commonly accepted at 6%). What voltage do you see at 20-30A? You may be stressing something there, might be good to have them help you review it.
     
  10. cinergi

    cinergi Active Member

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    I LOVE listening to that genre in the car because it sounds good (including the right amount of bass) to me :smile:

    - - - Updated - - -

    I didn't try a number in between. It seemed like a relatively linear dropoff so I'd guess 30 amps would have been 231 volts.
     
  11. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    That would point to being near capacity on the service entrance facilities and/or transformer even without charging, because it would be an exponential drop-off near the high-end of the charging current if there were more capacity. I'd arrange to have the PoCo out and do a voltage analysis of your incoming service (or you can measure voltage at another unloaded 240V outlet on another circuit) as you charge at various currents.
     
  12. widodh

    widodh Model S R231 EU

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    Good to hear! Now I know that my Open EVSE is capable of charging my future S. Thanks!
     
  13. Zextraterrestrial

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    Do I 'need' a second charger?

    I didn't really think about the 70A J1772 since I didn't think there were many out there. I figured if I want to go through Oregon / Washington I'd use superchargers or slow RV chargers. But are there 70A 1772's around that I'd want to use?
     
  14. Robert.Boston

    Robert.Boston Model S VIN P01536

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  15. mitch672

    mitch672 Active Member

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  16. ChadS

    ChadS Petroleum is for sissies

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    Most of the North half of the 70A chargers (say, Woodland CA and North) have Tesla Roadster connectors. So you would need Tesla's adapter to use them with your Model S. They are currently backordered. They were never available in big quantities, so Tesla was only offering them to Roadster owners.

    Most of the South half of the chargers (Davis CA and South) have J1772 connectors. So you can use them with just the J adapter that comes with the Model S. But if you're going that way, you'd probably rather use the Superchargers.

    There are exceptions to these. I note them in the map where I know about them - but sometimes they change, and I have no way of getting notified...
     
  17. milotron

    milotron Member

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    Question about open EVSE and single chargers: If the EVSE if built to support 75 amps, can the full 10kW of the single charger now be properly utilised by setting the pilot signal to the correct higher ampacity, ( say a full 40amps, versus 80% of 40 amps per electrical code for the receptacle/circuit rating ) that is in excess of the single chargers rating. Of course it won't draw more than it is capable of, but could charge somewhat faster. I don't have my MS yet so I cannot confirm this...
     
  18. ElSupreme

    ElSupreme Model S 03182

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    No the charger is rated for 250VAC and 40A (250 * 40 = 10kW), not really 10kW. You can't exceed either value, if the stars align you get 10kW.

    Most everyone without a HPWC is using a 50A plug (either NEMA 6-50 or 14-50) that can provide 40 continuous amps.
     
  19. FlasherZ

    FlasherZ Sig Model S + Sig Model X + Model 3 Resv

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    The NEC requires 80% of 50A for the wiring and receptacle and doesn't apply to the car, which is governed by UL listing requirements.
    The UMC is rated at 50A, so that 40A continuous load can be delivered through it to the car at your reference voltage.
    The charger in the car is rated at 10 kW, 85-265VAC input. I don't know if it's been tested, but my guess is that you could squeeze 10.6 kW out of it if you had a 265V supply and let it draw 40A. The car might limit amperage to 37A or so to maintain max 10 kW, I'm not sure.

    Basically, if you have an OpenEVSE, the car will draw max of 40A at your nominal voltage if you only have a single charger.
     
  20. mitch672

    mitch672 Active Member

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    I use my OpenEVSE daily, but I have dual chargers. Even with dual chargers, I am seeing it draw 74/75 Amps, the voltage collapses from 239 to 220-221 at that load, the maximum rate I've seen so far is 43 miles/hour, but it's very cold here, and I'm sure that's affecting the rate as well (as some energy is going into heating the pack). As FlasherZ stated, the 14-50 outlet will provide the full 40A a single charger is capable of using, I doubt you will gain anything by providing 75A to a single charger Model S.
     

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