R1 derates charging to 24 amps on Tesla Universal Wall charger

[DKM_R1S]

I’ve been using a Tesla Universal Wall Charger to charge my Model Y and R1S for almost 2 years.
The install was coordinated by Qmerit and the electrician they contracted knew what they were doing. My neighbor also used them and would concur.

Recently I noticed that the R1S was only charging at 24 amps. This charger is on a 60-amp breaker and set to charge at 48amps.

Historically both vehicles always charged at 48 amps, there always has been some minor humming and warming of the conduit, but never what I would consider to be “hot” to the touch. Just warm. I was told this is normal.

I am able to replicate this event. Set the charging rate in the R1S to 48 amps. Start charging. Wait 10-15-20 minutes, then the charging rate drops to 24 amps.

I do not see this behavior with the Tesla.

If I set the R1S to charge at 40 amps instead of 48 amps (1) the charging rate remains at 40 amps without derating (2) there is no electrical humming and (3) the electrical conduit does not heat up.

Does anyone have any troubleshooting tips on steps I can take to determine the cause of the derating when trying to charge at 48 amps?

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[drumminguy81]

I ran into the same issue with mine, when I first plug in it will charge at 48a for around an hour but then drops down to 24a. What I found from reading online various sources with the same issue, it seems that the Rivian generates a fair amount of heat in the area of the charge port, this causes the charger plug to get warm. The Tesla universal charger is pretty sensitive to increases in temperature and throttles down the charge rate as a safety feature. This is a known Rivian issue and i suspect contributed to the change from j1772 to NACS charge port, but just a guess. To combat overheating I set my Rivian to only charge at a max of 42-44a while at home. I haven't seen this issue since making the change. There are other people that say to point a fan at the charge port but this seemed sketchy.. If the charger thinks its too hot I don't think I should be trying to trick it to think its not hot. btw I only see this issue in the summer when my garage is hotter.

 

[electruck]

This is to be expected of the R1 with J1772 especially when ambient temps are over approx 85 F. I just set my R1S to charge at 40A during the summer. And its not just the Tesla charger, Chargepoint and other brands experience the same issue (which I believe is with the port on the R1, not the plug end).

That said, this has been a thing for a number of years now. If this is the first summer you've noticed it, it could be an indication that something has changed. Perhaps worth checking the connectors for bugs or other contamination. I might normally also recommend re-torquing electrical connections on the charger but since your MY charges fine, that's probably not necessary.

 

[DKM_R1S]

I ran into the same issue with mine, when I first plug in it will charge at 48a for around an hour but then drops down to 24a. What I found from reading online various sources with the same issue, it seems that the Rivian generates a fair amount of heat in the area of the charge port, this causes the charger plug to get warm. The Tesla universal charger is pretty sensitive to increases in temperature and throttles down the charge rate as a safety feature. This is a known Rivian issue and i suspect contributed to the change from j1772 to NACS charge port, but just a guess. To combat overheating I set my Rivian to only charge at a max of 42-44a while at home. I haven't seen this issue since making the change. There are other people that say to point a fan at the charge port but this seemed sketchy.. If the charger thinks its too hot I don't think I should be trying to trick it to think its not hot. btw I only see this issue in the summer when my garage is hotter.

Very informative. Good to know this is a known issue with R1.

 

[BCondrey]

If the Tesla UWC has a red flashing light at the top, and at the same time it has the pulsing green lights going down the front, you have a temperature related derate. My wife's Tesla M3 does this when it is hot in the garage, and it is always derated to 24A. My Rivian used to do it to, until I installed a separate EVSE for it.

 

[DKM_R1S]

This is to be expected of the R1 with J1772 especially when ambient temps are over approx 85 F. I just set my R1S to charge at 40A during the summer. And its not just the Tesla charger, Chargepoint and other brands experience the same issue (which I believe is with the port on the R1, not the plug end).

That said, this has been a thing for a number of years now. If this is the first summer you've noticed it, it could be an indication that something has changed. Perhaps worth checking the connectors for bugs or other contamination. I might normally also recommend re-torquing electrical connections on the charger but since your MY charges fine, that's probably not necessary.

thanks for the reply. I was also wondering if you have that eletrical buzz/hum when charging at 48 amps? I notice a significant difference between 40 amps and 48 amps. 40 amps is nearly silent with little heat generated.

 

[DKM_R1S]

If the Tesla UWC has a red flashing light at the top, and at the same time it has the pulsing green lights going down the front, you have a temperature related derate. My wife's Tesla M3 does this when it is hot in the garage, and it is always derated to 24A. My Rivian used to do it to, until I installed a separate EVSE for it.

Yep, that is exactly what I am seeing.

 

[Time2Roll]

Tesla Wall Connector will also derate if the internal power connection gets hot.
No indication of error on the Tesla unit?

Easy to open and check the torque on the wires.

 

[DKM_R1S]

Tesla Wall Connector will also derate if the internal power connection gets hot.
No indication of error on the Tesla unit?

Easy to open and check the torque on the wires.

Like what BCondrey stated, I am also receiving the red flashing light at the top with green pulsating lights

 

[gvtucker]

Similar but different issue for me. I have a Rivian charger, and my R1T won't derate to a lower amperage. Instead, it blows a fuse. If I lower the rate to 36 amps instead of 48, it charges normally.

 

[BCondrey]

Similar but different issue for me. I have a Rivian charger, and my R1T won't derate to a lower amperage. Instead, it blows a fuse. If I lower the rate to 36 amps instead of 48, it charges normally.

By "blows a fuse" do you mean the breaker is tripping? Not sure that is heat related. I'm no expert but I would be concerned about this. What size is the breaker? If it is a 60A breaker and you are charging at 48A, there is no good reason for a trip unless something else is wrong.

 

[denverag03]

I charge a 2025 R1S on a Tesla UWC and recently noticed the same problem. I would end up with a situation like this. I got Tesla to ship me a new one under warranty and it has not happened again yet, but we'll see.

 

[BCondrey]

Looks like you get close to a solid 11kw from the Rivian EVSE. I plan to replace my 40A Grizzl-e with a Rician wall unit I have new in box. Is the 11kw accurate?

 

[denverag03]

I "named" my Tesla EVSE Rivian Wall Connector to keep it differentiated in Home Assistant from my other Wall Connector w/ a Model Y on it.

 

[gvtucker]

By "blows a fuse" do you mean the breaker is tripping? Not sure that is heat related. I'm no expert but I would be concerned about this. What size is the breaker? If it is a 60A breaker and you are charging at 48A, there is no good reason for a trip unless something else is wrong.

No, I mean it blows a 60 amp fuse. The breaker never trips. And it doesn't blow the fuse if I reduce the charging amperage.

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