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Mobile connector over heat?

I have the mobile connecter. I have a 50 amp breaker, 6 wire, use a 14-50 plug . Has worked great for last 2 1/2 years. Recently (last 6 months) the connector started getting hot and bumped down from 32 amp to 16 amp. I can unplug, plug back in and it resets to 32A, but after 20 min gets hot and drops to 16A. I changed out to a commercial 14-50 receptacle, torqued down the wires as per specs. Breaker is fine, all seems fine. But still happening. Can a mobile connector go bad?
 

jjrandorin

Moderator, Model 3, Tesla Energy Forums
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Nov 28, 2018
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Riverside Co. CA
Can a mobile connector go bad?

I have seen threads here where people end up having a bad mobile connector. If its possible to do so, try using your mobile connector at another known good spot, or, if you have a friend / family member with their own tesla mobile connector, try theirs in your setup.
 
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Do the contacts in the receptacle contact the entire plug blades, or just parts of the blades (you should be able to see looking into the receptacle holes)?

If the latter, there could be greater heat buildup which may be marginal in cooler weather, but warmer weather could push the temperature over the threshold that the mobile connector uses to tell the car to reduce charging rate.
 
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Do the contacts in the receptacle contact the entire plug blades, or just parts of the blades (you should be able to see looking into the receptacle holes)?

If the latter, there could be greater heat buildup which may be marginal in cooler weather, but warmer weather could push the temperature over the threshold that the mobile connector uses to tell the car to reduce charging rate.
Yes, they contact perfectly. I talked with Tesla, they said if it is charging during a hot part of day, the mobile connector has a protection feature that drops it to lower for safety. Local SC said they are getting lots of reports of this happening this month. So I guess all is working correct. The local temps have been in the triple digits both day and close to it at night.
 
Wow, @Ev_Rider, I just started experiencing this two days ago! I started a thread in the Model Y forum and just saw your post.

Very similar here, 50-Amp breaker, 6-gauge wire, 14-50 plug, and has been working fine for three years charging at 32A for previous Model S and now Model Y...until two days ago. We are in a heat wave and yesterday was 106 degrees outside but I'm charging overnight and charging typically doesn't begin until 12:30am or 2-3am, seemingly plenty of time for things to cool down.

I inspected 14-50 wiring and it all looks good, no fraying and no signs of melting or overheating. No error faults in the car, but I noticed this morning charging hadn't completed and was only showing 239V 16A/16A rate instead of the usual 32A/32A. I found other threads that suggest this behavior typically led to replacement of the car's onboard charger. I am curious how Tesla fixes your issue.

I did notice this morning that the in-car charging screen was set at 48A, which is odd. No one has touched the setting and it normally should be 32A. I reset it to 32A and did a brief 20-minute charging session and all looked normal and the rate stayed at 32A. I still scheduled service for August 26th and Tesla is already planning to replace the mobile charger. I hope they take a look at the onboard charger as well.

Today is another warm day and the ladder in my garage registered 95 degrees but the mobile charger is showing 110 F. I am not sure if this is normal or not. The mobile charger is plugged into the wall but not actively charging:

B7C75FEA-5665-4740-AF65-9E5B8F462F45.jpeg
 
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was only showing 239V 16A/16A rate instead of the usual 32A/32A
Actually, that's a sign that it's the mobile connector and not the car. The first number is what the car is charging at, and the second is the amperage advertised by the EVSE. This says to me that the mobile connector throttled things back to 16a. If it were the on-board charger, I'd expect you to see 16/32.
 
Actually, that's a sign that it's the mobile connector and not the car. The first number is what the car is charging at, and the second is the amperage advertised by the EVSE. This says to me that the mobile connector throttled things back to 16a. If it were the on-board charger, I'd expect you to see 16/32.
Thank you, Dave! Perhaps that is why the estimated invoice only listed replacement of the mobile charger, and no other diagnostic work planned. I think mine is the Gen2 mobile connector that came with our 2021 Y. Not sure if there's an updated UMC.
 
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Nauvoo

Member
Aug 7, 2021
41
110
NC
Recently had the same issue of charging amperage dropping to 16A, with the 'T' on the Mobile Connector flashing 4 times. (See attached PDF for what the diagnostic codes on the body mean) I have a 2021 Model S LR. I will give the details below, but one piece of data that was eventually shared by the Tesla Remote Technician (via Service Message on the App) was that the car data log only captures the Wall Plug Temperature when it exceeds 145F. They can give you the actual temperature. Mine was 149F. If I had known this, I would have changed the receptacle much sooner.

In the previous events, by the time I got to the plug to measure with my temperature gun it was in the 110F range, so I thought it was the Mobile Connector. On 8/10/22 I changed out my Leviton receptacle - #279-S00 (It was not discolored nor looked degraded) for a Hubbell #HBL9450A 240V/50A NEMA 14-50. It is on a 6/3(18 inch run inside the wall below the breaker panel) and 50A Circuit breaker dedicated circuit. (Also torqued the terminals to 75 in-Lb as required) Recently did an 8 hour overnight charge after a long trip with no issues. I checked the temperature of the plug every hour for 3 hours, never exceeded 102F on the plug head.

The Leviton was installed and used continuously on my 2018 Model 3 from 12/2018 to 8/2021. Then for my 2021 Model S LR since then. To get to this point, had 3 separate Mobile Service Calls, they replaced the Plug, then the Body and Cable. Honestly, if they had given me the 149F on the first issue, I would have replaced the receptacle immediately. It was all covered under warranty. Bottom line, as on many threads here, use a commercial/industrial grade receptacle for EV charging. Hint: Zoro.com has great prices on the Hubbell #HBL9450A and the required wall plate (it is 2.48" in diameter, the Leviton is 2.15") it is also 1.81" deep vs. 1.0" deep for the Leviton, so you need a deep double gang box to handle the 6/3 wire, one nice feature is it has both rear and side terminals.
Hope this helps.
 

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  • Gen2_UMC_Manual_en_US.pdf
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Recently had the same issue of charging amperage dropping to 16A, with the 'T' on the Mobile Connector flashing 4 times. (See attached PDF for what the diagnostic codes on the body mean) I have a 2021 Model S LR. I will give the details below, but one piece of data that was eventually shared by the Tesla Remote Technician (via Service Message on the App) was that the car data log only captures the Wall Plug Temperature when it exceeds 145F. They can give you the actual temperature. Mine was 149F. If I had known this, I would have changed the receptacle much sooner.

In the previous events, by the time I got to the plug to measure with my temperature gun it was in the 110F range, so I thought it was the Mobile Connector. On 8/10/22 I changed out my Leviton receptacle - #279-S00 (It was not discolored nor looked degraded) for a Hubbell #HBL9450A 240V/50A NEMA 14-50. It is on a 6/3(18 inch run inside the wall below the breaker panel) and 50A Circuit breaker dedicated circuit. (Also torqued the terminals to 75 in-Lb as required) Recently did an 8 hour overnight charge after a long trip with no issues. I checked the temperature of the plug every hour for 3 hours, never exceeded 102F on the plug head.

The Leviton was installed and used continuously on my 2018 Model 3 from 12/2018 to 8/2021. Then for my 2021 Model S LR since then. To get to this point, had 3 separate Mobile Service Calls, they replaced the Plug, then the Body and Cable. Honestly, if they had given me the 149F on the first issue, I would have replaced the receptacle immediately. It was all covered under warranty. Bottom line, as on many threads here, use a commercial/industrial grade receptacle for EV charging. Hint: Zoro.com has great prices on the Hubbell #HBL9450A and the required wall plate (it is 2.48" in diameter, the Leviton is 2.15") it is also 1.81" deep vs. 1.0" deep for the Leviton, so you need a deep double gang box to handle the 6/3 wire, one nice feature is it has both rear and side terminals.
Hope this helps.
Thanks for this. I will start charging early tonight and make note of temperatures. I see the manual stating 32A max for 14-50 adapter. I noticed the Y’s charging screen was set to max 48A “for this location” again this afternoon, even though I had reduced it to 32A this morning. The location is our garage.
 
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Garage is 93 degrees, 14-50 plug at the wall is 97 degrees while the body of the mobile charger is between 104-111 F. This is all while NOT actively charging.

I went ahead and started charging manually at 7:52 PM PST and will monitor it. For the first few minutes everything is looking normal, no red lights, just regular green streaming lights across the TESLA label on the mobile charger, rate ramped up to 32A. So far so good…

One hour in, 8:52PM PST, still charging normal (235V 32A). The 14-50 plug at the wall is 120 F, body of mobile charger is at 125 F, and main charging cable itself is 120 F. Hope these are all normal specs during active charging.
 
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The Leviton was installed and used continuously on my 2018 Model 3 from 12/2018 to 8/2021. Then for my 2021 Model S LR since then. To get to this point, had 3 separate Mobile Service Calls, they replaced the Plug, then the Body and Cable. Honestly, if they had given me the 149F on the first issue, I would have replaced the receptacle immediately. It was all covered under warranty. Bottom line, as on many threads here, use a commercial/industrial grade receptacle for EV charging.
Look into the plug holes of the Leviton outlet. You will see steel contacts that touch only about half of the plug blades. This will cause higher resistance and heat than the full length brass contacts in most other outlets (steel has lower conductivity, and half blade contact means half as conductive). This appears to be why Leviton outlets are marginal in a heat sense when charging at 32A, and may trip the heat sensor in the plug head of a Tesla mobile connector during warmer weather.
 
Garage is 93 degrees, 14-50 plug at the wall is 97 degrees while the body of the mobile charger is between 104-111 F. This is all while NOT actively charging.

I went ahead and started charging manually at 7:52 PM PST and will monitor it. For the first few minutes everything is looking normal, no red lights, just regular green streaming lights across the TESLA label on the mobile charger, rate ramped up to 32A. So far so good…

One hour in, 8:52PM PST, still charging normal (235V 32A). The 14-50 plug at the wall is 120 F, body of mobile charger is at 125 F, and main charging cable itself is 120 F. Hope these are all normal specs during active charging.
At 9:52PM PST (two hours of charging), the 14-50 plug head at the wall reached 125 F, body of mobile charger at 130 F, and main cable stayed at 120 F.

If the rate stays linear then the plug head and mobile charger body will trip the temp sensor in 3-4 hours. Alas, I don’t need any more charge and stopped at this point.
 
Look into the plug holes of the Leviton outlet. You will see steel contacts that touch only about half of the plug blades. This will cause higher resistance and heat than the full length brass contacts in most other outlets (steel has lower conductivity, and half blade contact means half as conductive). This appears to be why Leviton outlets are marginal in a heat sense when charging at 32A, and may trip the heat sensor in the plug head of a Tesla mobile connector during warmer weather.
Thanks. This makes sense, the Leviton is 1" deep, the Hubbell is 1.8" deep.
 
Thanks. This makes sense, the Leviton is 1" deep, the Hubbell is 1.8" deep.
Depth is not relevant, except for fitting into outlet boxes (the Leviton fits more easily into small outlet boxes due to its smaller size, although the wire entry on the back means some space is needed behind the outlet itself).

Leviton steel partial contacts shown here:

Compare to brass full contacts shown here:
and here:
 
Thanks for the extra info from this thread. Turns out our receptacle is Leviton, which probably has something to do with the recent charging issues. I tried to follow all the latest NEMA 14-50 install guidelines but must’ve missed the receptacle posts/recommendations three years ago.

Aside from having to tighten one of the wire screws on the Leviton receptacle, the Y seems to be charging normally at 32A now. I am still concerned about the mobile charger body, plug, and cable measuring between 123-130 F during charging (garage is 102 degrees at 8pm tonight); no signs of overheating or melting anywhere. Looks like it’s about $88-112 now for a Bryant/Hubble receptacle. I went ahead and ordered the Hubble and will swap it in when it arrives in a few days.
 
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My Dad and I swapped in the Hubbell receptacle today to replace our 3-year-old Leviton. The Hubbell definitely feels heavier duty compared to the Leviton. The Allen screws and plate contacts provide a confident and secure hold on the 6 AWG wires. I also ordered the $60 Eaton/Cooper for comparison but decided to install the copper-only $112 Hubbell.

I compared temperatures after one hour of charging and was surprised to see the wall plug is almost 10 degrees cooler with the Hubbell! The body of the charger and charging cord also stayed cooler during operation. The garage temperature was almost identical between both sessions when taking these readings. The Hubbell is pricey, even more so today than a few years ago, but the durable and quality construction gives me peace of mind and I’m glad to make the swap away from the Leviton.

B787FAAE-8597-4F1D-A7B8-858EF4992F85.jpeg
 
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Do the contacts in the receptacle contact the entire plug blades, or just parts of the blades (you should be able to see looking into the receptacle holes)?

If the latter, there could be greater heat buildup which may be marginal in cooler weather, but warmer weather could push the temperature over the threshold that the mobile connector uses to tell the car to reduce charging rate.
I suspect your theory is %100 correct! I'm on Phoenix and my garage never gets below 105 F from May until Mid October! These concerns and issues are relatively new and it's because of a larger population of Tesla customers!
 
I changed out receptacle to a Bryant, still had issues. What finally resolved it was to set the car back to 30A rather than the normal 32A. That seemed to reduce the heat load. It did bump it down to 7kw rather than the 8, but no big deal for me as it is charging all day or overnight anyway and slightly reduced charging speed is not an issue.
 
Hi, all. Tesla's gen2 MC manual says it has operating temperatures of -30C to 50C (122F), so it sounds like you're just on the edge of the range. Has anyone tried approaching this with a heatsink or cooling fan or some other heat dissipation solution?

I just ordered my MYLR here in Taiwan. It definite gets triple digits here for half the year, so I'm concerned about whether I can use the Mobile Connector as my main charger normally. My parking spot is outside my apartment building, no garage, right by the alleyway. (The Tesla Wall Charger is triple the price of the NEMA 14-50 here, and the NEMA charge speed is much more than enough for my needs, so I don't want to pay more unnecessarily.)

Thanks in advance!
 
Hi, all. Tesla's gen2 MC manual says it has operating temperatures of -30C to 50C (122F), so it sounds like you're just on the edge of the range. Has anyone tried approaching this with a heatsink or cooling fan or some other heat dissipation solution?

I just ordered my MYLR here in Taiwan. It definite gets triple digits here for half the year, so I'm concerned about whether I can use the Mobile Connector as my main charger normally. My parking spot is outside my apartment building, no garage, right by the alleyway. (The Tesla Wall Charger is triple the price of the NEMA 14-50 here, and the NEMA charge speed is much more than enough for my needs, so I don't want to pay more unnecessarily.)

Thanks in advance!
Those quoted temperatures should be for the ambient temperature to operate the unit in, not the temperature that individual components might reach during operation. It should work. However, if it's going to be installed outside, particularly somewhere that gets a lot of rain, I'd seriously consider going with the wall connector, as the mobile connectors aren't built for weather exposure. If you want to do the mobile connector, consider installing some sort of rain and sun protection for it.
 

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