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Melted new 14-50 adapter after one charge

Discussion in 'Model S: Battery & Charging' started by Bucket22, May 29, 2014.

  1. Bucket22

    Bucket22 P85 / #3287

    Mar 9, 2012
    I know that there are multiple threads about old 14-50 adapters melting, but I didn't see a report of one of the replacement adapters melting, so I thought I'd post my recent experience. Over the last couple of weeks, I noticed a few mornings that my car was stopping short of its scheduled charge (90%, scheduled to start in the wee hours). One time, it reduced the charging rate to 30A and a couple of times the ring around the charge port was red when I unplugged in the morning. Perhaps foolishly, I thought I had not inserted the charge cable completely and I didn't think much of it. I had been using my original adapter and UMC from January 2013. Then my replacement 14-50 adapter arrived in the mail. I went to swap it out and discovered that the old 14-50 was quite melted:
    photo 1.JPG

    I called Tesla Service the next morning and sent them a picture of the melted adapter. They said that this was a problem the new adapter was meant to address, so hopefully the new adapter wouldn't have this problem. To be "100% safe", they asked me to send a picture of UMC connector. I had used the new adapter to charge the night before for the first time. When I checked, there was indeed some melting on the UMC. There was also some melting on the new gray 14-50 adapter, which had only been used for a couple of hours of charging the night before:
    photo 2.JPG
    photo 3.JPG

    A Tesla Service valet brought a new UMC and adapter to my house a couple of hours later and I have successfully charged a couple of times since then.

    I don't claim to have a thorough understanding of the adapter change, nor of electrical issues generally. Presumably, this was an issue that my UMC developed 16 months into use. However, I thought it was noteworthy that the new 14-50 adapter did not eliminate the possibility of melting.
  2. ElSupreme

    ElSupreme Model S 03182

    Jan 13, 2012
    Atlanta, GA
    The UMC side of the connector was very visibly burned/melted and damaged. Putting the new adapter on and having it melt isn't at all surprising. With a undamaged UMC side and a new undamaged adapter side you should have no problems.
  3. Bearman

    Bearman Member

    Nov 17, 2011
    I have never seen the car side connection melt, maybe they should just make a 14-50 adapter to tesla type that stays put and have the cable be tesla type on both ends. Who ever made this type of connection should be punished, they are melting like chocolate.
  4. qwk

    qwk Model S P2681

    Dec 19, 2008
    In my experience, the UMC side always melts first, then the melting of course transfers over to the adapter. By putting a temp gun on the UMC end, it appears that the crimps/welds on the pins loosen over time, which leads to excess temps, and melting.
  5. ThosEM

    ThosEM Space Weatherman

    Dec 13, 2013
    Annapolis, MD
    Agreed; the problem comes from conducting pins or sockets on either side of the connection becoming coated with contamination that reduces the metal-to-metal contact area of the pin-socket junction, increasing its resistance and causing some energy to be dissipated there instead of inside the car. Any connector that has been melted has in the process released considerable amounts of plastic volatiles that coat anything and everything nearby, including the metal surfaces. Then there is no way to get a good solid connection without at the very least a meticulous cleaning of all the metal surfaces. Also, the melting may have distorted the metal sockets or their placement in the plastic plug, reducing their pin contact area mechanically. The safest thing is to swap out both sides of any junction that shows melting to assure clean surfaces will be present in the future.

    Writing that down makes me wonder if there should not be a method developed for periodic inspection and maintenance of the pin/socket connections to assure that they are cleaned if they show any signs of contamination or distortion, preferably before they get melted ;=)
  6. yobigd20

    yobigd20 Well-Known Member

    Oct 28, 2012
    Skaneateles, NY
    They should have used twist locks in the first place. This is just a PR mess.
  7. David99

    David99 Active Member

    Jan 31, 2014
    Brea, Orange County
    What do you mean by 'twist locks'?
  8. TonyWilliams

    TonyWilliams Active Member

    Jun 11, 2012
    San Diego - Tesla powered Rav4 EV
    The following UMC didn't melt becasue there was a problem with anything except the welding from the pin to the conductor within the plug.

    I cut open the Tesla NEMA 14-50 plug with the failed connection within "Line 2" (the red wire):


  9. tezco

    tezco Sig P85

    Nov 9, 2012
    #9 tezco, May 29, 2014
    Last edited: May 29, 2014
    These are designed to hold the connection together more securely. You mate the plug and receptacle and twist about 30 degrees to lock the two together.

  10. invisik

    invisik Supporting Member

    Mar 13, 2014
    So what should be used to periodically clean the connectors? Like a wire brush battery terminal cleaner? (it all reminds me of needed to clean battery terminals and battery cables from time to time)


  11. woof

    woof Model X 75D Blue. Model 3 LR Red.

    Apr 30, 2009
    The cause of the melting is obviously due to a build-up of carbon, that is carried down the wires from a power plant that is burning coal or natural gas. Tesla has a patented filter in the UMC adapter that attempts to stop the carbon from getting into the car, but sometimes with extremely dirty power it gets clogged and eventually overheats. You can clearly see the carbon clogging up the copper in Tony's picture. The newer adapter can handle more carbon than before, but if you didn't clean out the old one before switching over it can obviously still be overwhelmed.

    This isn't a problem for owners whose power is supplied from hydro, or who use solar or buy "clean" energy contracts. There are some "products" you can buy that plug in and claim to clean out the carbon from wires, but they are all scams--don't use them. Instead, switch your electricity supplier and then call up the old one and have them clean out all the carbon from your wires that their dirty power generation caused. Only a professional cleaning can solve the problem for good.

    Once the wires and power are clean you'll find the Model S charges faster and runs smoother too.
  12. sefs

    sefs 2012 Ford Focus Electric

    Dec 23, 2013
    Gibsonia, PA

    I really hope that was a joke.
  13. Seattle

    Seattle Member

    Dec 9, 2012
    Bellevue, WA

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