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Too hot?! - mobile connector in NEMA 14-50

Discussion in 'Model S: Battery & Charging' started by SabrToothSqrl, Mar 14, 2015.

  1. SabrToothSqrl

    SabrToothSqrl Active Member

    Dec 5, 2014
    Charge most nights at home, just fine, inside my garage. NEMA 14-50, 6 gauge wired. Charges at 39/40 or 40/40 amp for hours and most nights.

    But, sometimes it drops to 30! I called the road side # and they said call local center when it happens. I did. Goes in Monday for a small list of issues.

    I can't figure out why its dropping. 50 amp breaker. Total of 2' run. It's litterally 1' below my main breaker.

    It does get warm though, and I wanted to see temps you guys have. I used my trusty Harbor Freight contact less infrared laser pointer thermometer to finally get some readings.

    After approx 6 hours of 40 amp charging: (F)
    in order of wall --> car.

    NEMA wall outlet: 97.7
    Mobile connector to NEMA 14-50 adapter: 134.9
    mobile connector 'end': 142.1
    green light cylon part: 91.4
    wire near connector at car: 80.7

    garage air temp: 55

    is this normal? I cleaned all connectors/connections. The NEMA 14-50 is a month old.

    My house is propane heat, so the furnace is not going to draw anything against my 200 amp service. Well pump shouldn't cause issue.

    Even my stove is propane. And hot water heater. Only the dryer might be a load, but I can't find any rhyme or reason for the power drops.

    90% of the time it rides 40 amps all night... Well I should say my daily commute means only 2-3 hours of charging. I haven't enough data yet to know if it's dropping to 30 amps after 4-6 hours.

    If i run that visible tesla app, will it give me more insight to the charging amps over time?

    thanks guys. I just want to know if it's the car, charger (I do have dual) or the house.

    I can't see putting in a HPWC if I can't even rock a steady 40 amps. Nor does my normal commute require one.
  2. FlasherZ

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

    Jun 21, 2012
    It will get warm, but not that warm. It's likely you have a defective adapter or UMC (perhaps slightly bent pins that aren't contacting correct or something). Contact your service center with your temperature readings and they'll help you.

    It may be the reason for your current limiting, but also may not be. You won't know until you address the temperature of your current UMC.

    - - - Updated - - -

    "Trusty" and "Harbor Freight" never belong in the same sentence. I have plenty of HF stuff, but it's throwaway and not "trusty". :)

    Note that the infrared sensor is not reading at the precise point where the laser points, it's about a 4-6" diameter sense area, so it's hard to be extremely specific. That said, the temp rise you're seeing is not normal.

    As for the reasons why the car will back off, see the FAQ, referenced in my signature.
  3. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

    Mar 8, 2012
    Basically, if you touch the UMC and it's "ouchie" hot, you need a new one. Contact your Service Centre.
  4. SabrToothSqrl

    SabrToothSqrl Active Member

    Dec 5, 2014
    #4 SabrToothSqrl, Mar 15, 2015
    Last edited: Mar 15, 2015
    No worries, "trusty" was meant to be a humorous term for their tools. And you are correct, it reads a 4-6" area or larger based on distance. I used it pretty close to the surface to minimize cross readings. For $20 though, it's a sweet little tool.

    At 141, it is too hot to hold. No, not vanilla ice. Seriously you can't hold the adapter for more than 30 seconds or so.

    I'll take the whole setup to them on Monday. I wonder if any of the pins going into the adapter sense temperature?

    high heat in an electrical device is usually indication of an issue. I just didn't know how high was abnormal.

  5. SabrToothSqrl

    SabrToothSqrl Active Member

    Dec 5, 2014
    Good new everyone!

    tesla replaced my mobile connector. Looks new to me.

    After 3 hours of 40 amps:

    NEMA wall outlet: 84
    Mobile connector to NEMA 14-50 adapter: 80
    mobile connector 'end': 82
    green light cylon part: 95

    garage: 67.

    Looks like a massive improvement all around.

    Hopefully it holds at 40 amps steady now. It's no longer HOT to the touch, just barely warm.
  6. UberEV1

    UberEV1 Member

    Mar 9, 2014
    San Jose, CA

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