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What to do with your old NEMA 14-50 plug adapter...Make a universal plug!

Discussion in 'Model S: Battery & Charging' started by KJennerator, Apr 27, 2014.

  1. KJennerator

    KJennerator Member

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    My dad was doing some experimenting with the UMC to discover how it determines which adapter is plugged into it. The goal was to get 24 amps from a 120V source without buying the proper adapter from the Tesla store. It turns out that the two communication pins (shown in the picture below) have a resistance across them, and this resistance tells the UMC which voltage and current it should look for.

    adaprer drill and assemble parts.jpg adapter assemble and set to 30k.jpg

    Drill till you get an open between ground and sense. Adjust the pot to 30k Ohms and it will take 120-240vac at 24amps.

    What do you guys think?
     
  2. scaesare

    scaesare Active Member

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    Yup, he is correct in how it works...

    There's a post around here somewhere that has the values spelled out... I can't find it at the moment, but it should give you what you need.

    Please be careful to label things appropriately...
     
  3. FlasherZ

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

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    Note that on older cars 120V charging is limited to 20A max. Only recently have we seen a car that can charge at 24A when 120V is present, otherwise the car's software limits it to 20A, no matter what pilot signal you present to the car.
     
  4. KJennerator

    KJennerator Member

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    Our early 2013 production charged at 24 amps on 120v by changing resistances across ground and sense on the standard 120 socket.
     
  5. gaswalla

    gaswalla P4201/85/airsusp/pano/19i

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    The irony of tesla spending money to send new adapters for safety, and thus resulting in creating projects like this
     
  6. qwk

    qwk Model S P2681

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    Exactly my thoughts.
     
  7. FlasherZ

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

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    You'll never stop the innovators from "innovating" when it saves $10 or 10 minutes at the risk of life and property safety. :) It's not just in Tesla-land, it's everywhere. Read electrical or construction forums, someone asks "can I do this?", the reply from experts is "that is against code and would be extremely unsafe", and then that someone begins to argue how it's not really unsafe and the code-writers are secretly agents of <his-hated-political-party-here>. All the experts can do is note that there are insurance and liability implications, strongly warn against it, and pray the poster doesn't lose his life or the life of a family member, or his home.
     
  8. JPP

    JPP Active Member

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    ...and when TM does NOT get the old adapters back, and when there is an issue with the old ones (melting, fire, etc), who's fault is it?
     

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