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High temperature detected by Wall Connector alert

WSE51

Member
Aug 24, 2012
123
87
Southern California
I have 2 Tesla Wall Connectors in my garage, with a comm link running between them. Three Teslas share the two connectors, often with two cars charging at once.

After serveral years of no issues, lately I have noticed that the left-most Connector sometimes charges very slowly, like 19 amps, even though it is on a 100 amp circuit and usually charges the Model X at 72 amps if no other cars are on the other connector.

Tonight I noticed on the dashboard of the MX the error message "Charging speed reduced. High temperature detected by Wall Connector"

I removed the charing cord. I was not hot. I felt the Wall Connector itself, and it was also not hot. I plugged the MX into the right-most Wall Connector, and it is charging at 72 amps. The weather is not hot, and the garage is not hot.

This implies the problem is in left-most Wall Connector, but why would it give this error message if it was not hot? And only sometimes? Any suggestions appreciated.
 

JHCCAZ

Supporting Member
Feb 2, 2021
184
314
Tucson
I have 2 Tesla Wall Connectors in my garage, with a comm link running between them. Three Teslas share the two connectors, often with two cars charging at once.

After serveral years of no issues, lately I have noticed that the left-most Connector sometimes charges very slowly, like 19 amps, even though it is on a 100 amp circuit and usually charges the Model X at 72 amps if no other cars are on the other connector.

Tonight I noticed on the dashboard of the MX the error message "Charging speed reduced. High temperature detected by Wall Connector"

I removed the charing cord. I was not hot. I felt the Wall Connector itself, and it was also not hot. I plugged the MX into the right-most Wall Connector, and it is charging at 72 amps. The weather is not hot, and the garage is not hot.

This implies the problem is in left-most Wall Connector, but why would it give this error message if it was not hot? And only sometimes? Any suggestions appreciated.
Here is a very informative thread, especially if you understand something about electronics. The post author did an extraordinarily thorough and competent job of troubleshooting his overheating Gen3 Wall Connector (HPWC), uncovering a manufacturing QC issue as well as arguably a design issue. I just happened to see it yesterday, and then see your post just now, so I'm passing the info along to you.

In summary, it is found, and apparently acknowledged by Tesla, that older versions of the Gen3 connector can have an assembly defect in the relays, causing a high-resistance contact flaw that can overheat badly.

If you have the Gen3 model with the detailed model number ending in "F" (or possibly earlier) yours could be affected. If the model number ends in "G" it was supposedly fixed, so if that's the case your problem could be from a different cause.

The model number can be seen on the right side of the housing, and I think also within the app.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,271
7,334
Boise, ID
@JHCCAZ While that is a great thread about the Gen3 wall connectors, I don't want you misleading @WSE51 since this thread is about Gen2 wall connectors, which are totally different and were not known to usually have any overheating problems.
 
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JHCCAZ

Supporting Member
Feb 2, 2021
184
314
Tucson
@JHCCAZ While that is a great thread about the Gen3 wall connectors, I don't want you misleading @WSE51 since this thread is about Gen2 wall connectors, which are totally different and were not known to usually have any overheating problems.
OK, I didn't pick up that the OP said he had Gen2. (He said he has "2 Wall Connectors"). Anyway, I wasn't sure what he had and that's exactly why I wrote, twice, that the information was specifically about Gen3 of a particular revision.

I guess the statements regarding charge rate give it away; I just looked at the Gen3 and it specs only up to 48A.

No intent to "mislead".
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,271
7,334
Boise, ID
Saying they are on a 100A circuit and saying that they are set up with a load sharing system with the communication cable run between them for that purpose are both things the Gen3 doesn't do. I know it wasn't intended to mislead. I just didn't want the OP chasing rabbit trails trying solutions and ideas that didn't apply.
 
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JHCCAZ

Supporting Member
Feb 2, 2021
184
314
Tucson
Saying they are on a 100A circuit and saying that they are set up with a load sharing system with the communication cable run between them for that purpose are both things the Gen3 doesn't do. I know it wasn't intended to mislead. I just didn't want the OP chasing rabbit trails trying solutions and ideas that didn't apply.
I'm just coming into the Tesla world, installing a Gen3
(amidst a significant upgrade to get a decent feed to a new subpanel at opposite end of my house where the car will be - I elected to update my old main panel also but that job is on hold for equipment shortage, my electrician just got the panel but the meter base is still on backorder).

So I don't know the history of the Gen2 to Gen3. I'm a little surprised to see a downgrade in max current (after all it's called a High Power Wall Connector) and I guess there must have been some consternation over this for certain car owners. Maybe the niche of 50A to 80A home charging isn't big enough to justify the more expensive design.
 

WSE51

Member
Aug 24, 2012
123
87
Southern California
Thank you all. Yes, these are Gen 2 Wall Connectors. @JHCCAZ has given me some excellent ideas via PM which I need to test out. First I need to drive the cars more so I can observe charging behavior and compare the versions Teslas and across the two Connectors. They are currently nearly fully charged and in these COVID days we are not driving as much as before.

I will report bad on any useful findings.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,271
7,334
Boise, ID
So I don't know the history of the Gen2 to Gen3. I'm a little surprised to see a downgrade in max current (after all it's called a High Power Wall Connector) and I guess there must have been some consternation over this for certain car owners. Maybe the niche of 50A to 80A home charging isn't big enough to justify the more expensive design.
Oh yeah--more than a little consternation. The Gen3 was woefully inadequate in a few ways, and it was pretty insulting to people that the wonderful Gen2 units for $500 were being replaced by these deficient Gen3 ones for the same $500 price. Significant downgrades:
1. Shorter cable--the cable length went from 24 feet to 18 feet, which has been a problem for several people.
2. Lower charging amps--a lot of people still have some of the older cars, which could charge at 80A or 72A, and now Tesla doesn't sell anything that can run that high.
3. Lack of circuit sharing--this is the one that is insane. Circuit sharing was a VERY important feature to a lot of people, and the Gen2s did that very well and basically flawlessly. And Tesla replaced it with this Gen3 unit that doesn't do that AT ALL. Sure, they have been saying they will probably, eventually get that rolled out in a software update, but Tesla does things in their own sweet time, and people have been waiting for this quite a while, with no indications of when or if that may come.

And then this unreliability with huge numbers of the Gen3s having either fake or real overheating has been just more salt in that wound.

I don't want to take credit that isn't due. Possibly the PM was from @Rocky_H. Anyway good luck and looking forward to your solution of the problem.
Nope, that one wasn't me either, but there are plenty of helpful people to go around.
 

WSE51

Member
Aug 24, 2012
123
87
Southern California
I have been experimenting with the "problem" Wall Connector I wrote about above.

A few nights ago I tried it at 48 amps on a newer Model S, and it charged for about 2 hours normally and then started tapering down, eventually reaching 38 amps before I stopped charging. The green light charging animation on the charger shell stopped at some point, which is odd.

Tonight I charged the Model X, limiting it to 40 amps. It charged for 3.5 hours without overheating. There was no sign on the dashboard of the charging amperage being reduced, but the green light animation stopped at some point even though charging continued normally.

If this winds up being repeatable, it is not so bad. I will just use my other Wall Connector when I need to charge at over 40 amps (The Model X can do 72 amps and my Signature Model S can do 80 amps).

Not sure why this particular Wall Connector developed an overheating problem at >40 amps. I got at least 2 years of solid higher amperage use from it before it developed this issue.
 

mxnym

Member
Mar 9, 2018
886
325
Bloomington, IN
If you are going to keep experimenting, buy a fire extinguisher and please do not charge overnight.
Yes, this. The HPWC specifically says not to install with aluminum wires, but if yours was installed that way, the expansion and contraction of the aluminum could have lead to loose connections over two years. Since they are terminated near dead-center in the back of the HPWC, you wouldn't necessarily feel the heat from that by touching the body. Also, even if they were installed with copper, if the connectors weren't torqued correctly or the wires weren't inserted 100% of the way in, you could still easily have a loose connection generating the same heat that you wouldn't necessarily be able to detect from the outside of the HPWC body.
 

WSE51

Member
Aug 24, 2012
123
87
Southern California
I've been in touch with Tesla support. They had me update the firmware (interesting process for Gen 2!) and I am going to test again as soon as I've driven the Model X long enough that there would be a multi hour charging session. The support person did not feel there was any danger. He said serious overheating, if it is going to be a problem, happens within minutes not after hours. I will not be doing an unattended overnight charging session .. whole point is to monitor it frequently to record what is happening.
 

MN-MS100D

Member
Dec 10, 2018
120
75
Minnesota
... The support person did not feel there was any danger. He said serious overheating, if it is going to be a problem, happens within minutes not after hours.
WRONG-O. Heat will build and build and build, and will start a fire at the exact moment you are in your deepest sleep.
 

Rocky_H

Well-Known Member
Feb 19, 2015
6,271
7,334
Boise, ID
He said serious overheating, if it is going to be a problem, happens within minutes not after hours.
WRONG-O. Heat will build and build and build, and will start a fire at the exact moment you are in your deepest sleep.
Yeah. Can I point out something that makes this pretty obvious? Electric code has this provision where you can't use 100% of the capacity of a circuit if it's going to run for more than 4 straight hours. Now why do you think that would be? Cycling use for shorter periods gives the wires a chance to cool down again, but long term continues to add to that heat--sometimes faster than it can emit it into the surrounding environment. You obviously don't get to see your wires most of the time, because they are somewhat surrounded and contained and insulated in places that can trap and build up that heat. And further, in later versions of the code, electric vehicle charging was just defined as always being considered a long term load like that. So this is pretty self-evident that heat build-up can very definitely be a long term thing.
 

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