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Charge Rate Reduced- Wall Plug Temperature High

I had this happen once a few months ago. It didn’t seem warm, and didn’t occur again so I assumed it was due to heat in the garage.

Happened again this evening. I didn’t get a notification when the car dropped the charge rate down, so didn’t check it right away. But I stopped it when I saw it was down at 16A and unplugged it. The mobile charger was warm to the touch, but not hot. The outlet felt fine. I took it apart to see if there was any writing issue in the 14-50, but it seemed fine. None of the wires felt warm, connections looked solid, no sign of melting.

Is it likely it actually did get warm, but cooled enough at the lower amperage that I didn’t notice anything? I would have expected to see something strange when I opened it up.

I guess an electrician makes the most sense, but I can’t help but wonder if it’s a prob with the mobile charger.
 

Sophias_dad

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Jul 29, 2018
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Massachusetts
Is it likely it actually did get warm, but cooled enough at the lower amperage that I didn’t notice anything? I would have expected to see something strange when I opened it up.
If its dropped to 16 from 32, its entirely likely that its cooled enough. If its a crappy leviton outlet the heating would be at the connection points inside the outlet so you might not see damage at the screw locations. The UMC is specifically trying to avoid allowing damage to be caused, so it might have turned down the current before damage became obvious.

Maybe try 15-30 minutes at max current, then immediately stop charging and pull the plug out of the outlet. If the side lugs are more than somewhat warm, you have a problem(be aware they may be HOT, so use care when checking them)
 
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CWFLY

Member
May 9, 2018
70
66
San Diego
Dude, you are not taking this problem seriously enough! It tells you the message right there on the screen that it is too hot at the plug. You need to pull the outlet and check for a loose connection that could be about to melt a wire and start a fire! This should have been emphasized a lot more in previous comments, rather than talking about shade.
Thank you!!!
I second that suggestion. Don't burn you house down!!!

And Kudo's to Tesla, for putting a temperature sensor inside the "plug".
 
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Recently started noticing charging times on my car taking longer and this time finally saw the message charging rate reduced - wall plug temperature high. I felt one of the prongs and it was pretty hot; which reminded me of a picture I took of the outlet a few months back. It showed signs of heat on that side. Normal? I think on average I charge about 30% a day for the past two years.
69F2261A-A519-4AA2-BE90-C88F6BC0FA7E.jpeg

I looked at my install receipt and it shows they charged 15 dollars for the outlet. I ordered the Hubbell on Amazon and will be inspecting the wiring as well.
 

Tronguy

Member
May 4, 2019
87
781
New Jersey
Recently started noticing charging times on my car taking longer and this time finally saw the message charging rate reduced - wall plug temperature high. I felt one of the prongs and it was pretty hot; which reminded me of a picture I took of the outlet a few months back. It showed signs of heat on that side. Normal? I think on average I charge about 30% a day for the past two years.
View attachment 724275
I looked at my install receipt and it shows they charged 15 dollars for the outlet. I ordered the Hubbell on Amazon and will be inspecting the wiring as well.
Yeah. That looks burnt to my eye, on the left. This Is Not A Good Sign.
A few points:
  • Do Not Take This As Business As Usual. Don't use that socket until you Do Something, unless you feel like having a house catch on fire is something you really, really want. I Am Not Kidding. Yes, if things start burning, that usually (but not always) leads to a short, and the breaker popping open. The phrase, "Ya feeling lucky, punk?" comes to mind. Don't Be That Guy The Fire Department Has To Talk To After The Fact. (I've seen that happen, once: A neighbor across the street from me had his garage, then the entire house burn nearly to the ground, while I watched. Cause: a refrigerator in the garage that caught on fire. The gas main got involved, not good. The fire chief saying to the homeowner, "I wish we weren't meeting under these circumstances.".. Not a fun conversation. Only good thing: Nobody died, including the family dog, although that last was a near thing.)
  • If you're not handy with a screwdriver, turn off the breaker and wait for the new socket. And a decent electrician. Otherwise, continue:
  • Turn off the breaker. Unscrew the plate on top. Pull the socket out. Look, very carefully, at any screws holding wires on. If things aren't badly damaged, see if the screws can be tightened. If you can put a half-turn or so on one or more of the screws, do so. Loose screws lead to high resistance and heating; a good tightening it up might be all that's needed. Put it all back together again, including the wall plate, turn the breaker on, then try charging your Tesla again. If it all works, good, but replace that socket ASAP, preferably with one that's not a $15-bottom-of-the-barrel special.
  • If there's signs of serious char, forget it. Leave the breaker off. Did you know that carbon is a decent conductor? Don't be that guy who finds out the hard way. Replace with a new one.
  • NEMA14-50's are not really designed for an infinite number of insertions/removals. The general idea is to plug in one's clothes drier or whatever once, and then disconnect/reconnect same only a few times in the lifetime of that socket. Each time one plugs in something and/or takes it out, there's metal contacts in there that wipe back and forth and spring-laden chunks of metal that move back and forth. If one is using the TMC and plugging it in and out all the time, rather than just leaving things there, after a year or three of this that socket might not be so good no more. Higher quality sockets will be better, but not doing the TMC shuffle (as in, buying an extra from Tesla or whoever and just leaving it plugged in) is a better idea.
 
Pulled the socket thankfully none of the wires showed signs of serious heat and all terminals were tightly secured. The brand is Leviton. I will still wait for the replacement outlet before I use charge again though.

Would you guys recommend cutting off and exposing new copper to clamp down on? Looks like there’s plenty of slack. The charging plug looks to be good as well; no scratches or scores.

I do occasionally use my welder on this outlet. Maybe it’s time to consider a wall connector?
7E73797B-881D-444E-B6FF-279803008FD0.jpeg
 

Tronguy

Member
May 4, 2019
87
781
New Jersey
Pulled the socket thankfully none of the wires showed signs of serious heat and all terminals were tightly secured. The brand is Leviton. I will still wait for the replacement outlet before I use charge again though.

Would you guys recommend cutting off and exposing new copper to clamp down on? Looks like there’s plenty of slack. The charging plug looks to be good as well; no scratches or scores.

I do occasionally use my welder on this outlet. Maybe it’s time to consider a wall connector?View attachment 724494
From what I can see here, looks like naked copper (good) going into the connector, although from the angle the phase with the red wire on it, I can't quite tell. So, no point in re-stripping.

I suspect that you've got an issue with the actual connector surfaces inside. I'm decent at itty-bitty connectors used in electronics systems with plug-in boards, not to mention the occasional mechanical switch. Both of those have either silver, gold, or some alloy or other. The general idea is that when one pushes a plug into a socket, the metal blades on the plug rub along the metal inside the connector, knocking off microscopic corrosion products so one gets, on each blade, a wide area that's gas-tight metal-to-metal contact. The "gas tight" meaning that oxygen and pollutants like SOx/NOx can't get at the mating surfaces and corrode them. The corrosion is sometimes conductive, but nearly as conductive as the bare metal. (This sometimes gets really interesting: aluminum wiring has this issue with aluminum oxide, which is truly a non-conductor, so getting a gas tight connection means higher forces to break the oxide off and keep it off. Don't do that right and houses burn down; enough houses did that back in the day when copper got expensive that aluminum-wired houses got banned.)
Thing is, then, that, inside the socket, one has contacts with some kind of plating on them. The plating that doesn't corrode usually costs $$, so there's every reason for a cheapie manufacturer to skimp on the expensive plating. Once the expensive plating gets rubbed off over time, one gets left with exposed base metal, which is about as conductive as one might expect. That is, not much.
As I said above, NEMA14-50's aren't really designed for tens of thousands of cycles; I'd guess nominal would be a couple of hundred, lifetime, with a thousand on a good day.
I've done work on gold-plated contacts; a good, thick plating might be 0.75 um, but the cheap, flash gold would be 0.05 um. Which will work for a little while, then bite one on the nether ends a couple of years down the road. I haven't done the research, as in, pulling out the real manufacturer's data sheets where this stuff gets specified. On consumer products like the above, it takes some serious digging to get past the "Buy Now! 5000, really cheap!" $BS that tends to pervade the on-line marketplace.
Finding serious reliability numbers? Ha.
The Wall Connector has hard-connected wiring contacts designed to Live Forever, so the connection to the breaker box is assured. The Tesla connector that goes into the car; dunno what the numbers are, but it looks like silver contacts in both the plug and socket, which is seriously good.
 

Sophias_dad

Active Member
Supporting Member
Jul 29, 2018
1,902
2,110
Massachusetts
Recently started noticing charging times on my car taking longer and this time finally saw the message charging rate reduced - wall plug temperature high. I felt one of the prongs and it was pretty hot; which reminded me of a picture I took of the outlet a few months back. It showed signs of heat on that side. Normal? I think on average I charge about 30% a day for the past two years.
View attachment 724275
I looked at my install receipt and it shows they charged 15 dollars for the outlet. I ordered the Hubbell on Amazon and will be inspecting the wiring as well.
That Leviton was junk when it was installed, and on a good (Hubbell/Bryant/Cooper) outlet the occasional welder plug swap should be no problem at all. That outlet looks extra-crispy already.
 
Such a big difference between the two outlets! The Hubbell can be easily taken apart and the Leviton had to be torn apart. Did not expect to see such a size difference between the two terminals!

Going to have to wait until I can closely monitor the car charging to test everything out. All terminals tightened to spec 75lb-in.
06439C6E-E381-40A3-8ECB-6C4F367C0236.jpeg

5E443CCE-5DEA-48F1-92B7-061BAF50219A.jpeg
 
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Tronguy

Member
May 4, 2019
87
781
New Jersey
Such a big difference between the two outlets! The Hubbell can be easily taken apart and the Leviton had to be torn apart. Did not expect to see such a size difference between the two terminals!

Going to have to wait until I can closely monitor the car charging to test everything out. All terminals tightened to spec 75lb-in.
View attachment 725820
View attachment 725837
Yeah, and note the bigger one has contacts that touch, implying more normal force giving a better connection; gold alloy plating that results in less corrosion over time, and, as you noted, larger, with more actual area in contact.
The smaller one looks like nickel plating, which would be cheaper and more likely to get corroded.
 
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I normally do not keep the Mobile Charger (MC) plugged into the 240V wall outlet when not charging my Model 3. Last week I plugged it in and then into the car and left it to start charging at the scheduled 10 PM time. Coming back later I noticed it was only charging at 16 vs 32 Amps and was only adding about 15 miles to the battery per hour. I also had the display warning that the wall plug temperature was high. Feeling the plug, outlet and charger, I found nothing to be more than slightly warm. I stopped and restarted the charging from inside the car, but nothing changed. I discontinued charging and tried again the next day with the same result. On a whim I unplugged the MC from the wall socket while the car was being changed to see if the contacts were hot. They were not, so I plugged it back in (the car was attached to the MC the entire time), and it started charging at 32 amps and the overheat warning went away. Did the same thing the next day and again it reverted to 32 amps when I unplugged the MC from the wall while the car was being charged at 16 amps and reconnected it. Today I plugged the MC into the car first and then into the wall outlet and it charged at 32 amps immediately and completed the charge at that rate. Not sure what this means but there is nothing wrong with my wall outlet. In my case, I think it is something with the temperature sensor in the MC.
 

Tronguy

Member
May 4, 2019
87
781
New Jersey
I normally do not keep the Mobile Charger (MC) plugged into the 240V wall outlet when not charging my Model 3. Last week I plugged it in and then into the car and left it to start charging at the scheduled 10 PM time. Coming back later I noticed it was only charging at 16 vs 32 Amps and was only adding about 15 miles to the battery per hour. I also had the display warning that the wall plug temperature was high. Feeling the plug, outlet and charger, I found nothing to be more than slightly warm. I stopped and restarted the charging from inside the car, but nothing changed. I discontinued charging and tried again the next day with the same result. On a whim I unplugged the MC from the wall socket while the car was being changed to see if the contacts were hot. They were not, so I plugged it back in (the car was attached to the MC the entire time), and it started charging at 32 amps and the overheat warning went away. Did the same thing the next day and again it reverted to 32 amps when I unplugged the MC from the wall while the car was being charged at 16 amps and reconnected it. Today I plugged the MC into the car first and then into the wall outlet and it charged at 32 amps immediately and completed the charge at that rate. Not sure what this means but there is nothing wrong with my wall outlet. In my case, I think it is something with the temperature sensor in the MC.
I tend to agree with your assessment. Should be a warranty on the thing; contact Tesla (ha!) and ask. I think that I read on a Tesla forum somewhere that a punter had an issue with his MC; took it (and his car) to a Service Center, and they gave him a new one on the spot. But I think that the car, in that case, was spanking new. If your car is getting up there in age they may not go for that.
 

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