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40A OpenEVSE UMC replacement

Discussion in 'Model S: Battery & Charging' started by mitch672, May 28, 2014.

  1. mitch672

    mitch672 Active Member

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    #1 mitch672, May 28, 2014
    Last edited: May 28, 2014
    I bought one of Tony's Model S UMC connectors, and used Chris Howell's new European OpenEVSE board (it is capable of directly running 240V contactors), along with a 40A contactor, and some of Tony's UMC replacement cable (similar cable to the UMC), to build a 40A OpenEVSE... why you ask? who not... why do men climb mountains, because they can :)

    It runs considerably cooler than the Tesla UMC as well, I used 8AWG SEOOW 105 degree C insulation (rated for 40A, but it doesn't even get warm) for the input, on a 14-50 plug. The EVSE cable (basically a copy of what Tesla is using), does get a bit warm. I had to splice the connector to the cable, I used the new solder butt connectors that you heat with a hot air gun to make the connections, seems to work well. All of the splices are then encapsulated in a larger piece of heat shrink.

    You might notice I have the OpenEVSE set at 41A, that's one advantage of OpenEVSE, you can adjust the pilot.. I can adjust it in 1A increments from 40A up to 45A (which is %90 of the 50A breaker), under certain conditions you can try and push it. Of course it has lower settings too, such as 12, 15, 16, 20, 24, 30, 35, etc as well)

    Photo's
    40A-OpenEVSE Photos by mitch672 | Photobucket

    Slideshow:
    40A-OpenEVSE Slideshow by mitch672 | Photobucket
     
  2. TonyWilliams

    TonyWilliams Active Member

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    What relay did you use?

    We plan to manufacturer a version of what you did in the near future; basically an improved UMC for J1772, Roadster replacement and Model S.
     
  3. mitch672

    mitch672 Active Member

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    #3 mitch672, May 28, 2014
    Last edited: May 28, 2014
    Relay label can be seen in picture below. Chris actually sent me the relay, it's a "Packard C240C" (made in China). The smallish PCB next to the OpenEVSE is a 3.3V power supply I bought awhile ago, before Chris pointed out that you can just use (3) diodes in series to drop down the 5V to 3.3V close enough to run the 3.3V UMC door release circuit on the Blue wire.

    EE00E95D-0F7A-418B-BA56-021235A55EC6_zpsnu6illha.jpg
     
  4. invisik

    invisik Member

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    Please forgive me for a slight hijack, but with the EVSE project, could it be configured to charge from 2-40AMP lines simultaneously safely? Trying to find a way to utilize my dual chargers at 80amp while at a campground to reduce my charge time. I wish the car simply had two charging ports.

    Thanks.

    -m
     
  5. mitch672

    mitch672 Active Member

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    Nope. That's difficult to do, as you would need to match phases, and due to different wire lengths feeding the campground, and different breaker conditions, you'd likely have an unbalanced load, and it would overheat a breaker. Also, if they are using 3 phase power, it's almost impossible to get it working, due to out of phase conditions. There are threads on this subject, and some people have built combiner boxes, with various degrees of sucess... It's really a crap shoot on if it will work, and it's fairly expensive to build, with all of the correct relays/contactors and logic/safety systems required to make it "safe". On top of that, it's just not going to work at RV parks with 3 phase power.
     
  6. invisik

    invisik Member

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    Thanks. I have read a bit about it here. Thought that maybe the more advanced circuitry of the EVSE board might be able to handle it better. Ok thanks.

    -m
     
  7. qwk

    qwk Model S P2681

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    The easiest way to do this is with a direct wired HPWC. You will need some of the more common 100A breakers to tie directly into the panel. A good understanding of electrical systems is necessary though, or you will get hurt.
     
  8. TonyWilliams

    TonyWilliams Active Member

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    It may be possible to rewire the second onboard charger on the Model S for its own 40 amp charge port. That's a future project for the Rav4 EV.
     

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