Problem with Tesla Universal Wall Connector

[Time2Roll]

After installing 2025.22.30 today and attempting to charge in the middle of the day at home, the highest I could charge was at 24 amps. As I mentioned before I have a schedule that allows charging overnight, but I did press the charge now button. The charge started at 24 amps and the option to raise the amperage was grayed out. This occurred whether a car was plugged into the other wall connector or not. I'm curious if anyone else has experienced this yet.

If the option to reduce was available it would seem the EVSE unit is limiting the power.

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[Lester Green]

Agreed, I feel like it is an undocumented "feature". That said, I need to test more and see what Rivian support says. If it was changed purposely, they cut my charge rate in half. That is not good.

 

[p5k6]

Random thought (mainly cause this happened to me last night). I've had issues occasionally where one or both of the Tesla chargers loses a wifi connection (no idea why, reception is quite good in the garage ). When this happens, each charger defaults to it's load sharing profile (i.e. 40A for me) for presumably safety reasons, since they can't communicate. It's easy to miss - the light on the charger will blink green very subtly.

No idea if this might be the case, but figured I'd throw it out there.

 

[jrmbadger]

I'll chime in here as I have a similar setup.

I have a 60 amp circuit fed by 6 gauge THNN wire in conduit that is connected to a Universal Wall Connector. The UWC is then daisy chained with THNN wire in FMC to a GEN 3 wall connector that charges the Rivian. The UWC is the leader in the group power share and its setup to pull 48 amps max. I tried your scenario and started charging my R1S. I then started charging my MY LR. No issues. It backed off to 24 amps as expected. No issues going the other way as well.

I'm using the adapter that comes with the UWC on the R1S (even though I charge the tesla on the UWC and the R1S on the regular Wall connector). This is because of my garage layout and the charging port locations, and it being cheaper to utilize the UWC as a daisy chain rather than having a separate splitter box and having to buy polaris or other heavy duty connectors.

I have noticed some things that are interesting. If you start charging one car and the other car is plugged in and awake, but not charging, the highest amperage you will get is 42 amps on the car that is charging as it reserves 6 amps for the other car.

I've also noticed that sometimes the MYLR gets confused and sets the amperage level in the car to 24 amps even though the R1S is not charging and it should be 48 amps.

Finally, the Tesla energy graph is not great. Lots of missing data where it doesn't show anything. The charge history is also several days behind. Further, the Rivian charge stats also seem somewhat unreliable. At one point it said it was pulling 11.9kw, while the Tesla app said 11.4. Not sure what that was about.

My Gen 3 wall connector is on firmware 25.18.0 and my UWC is 25.18.0 as well. My R1S is a gen 1 2023. Perhaps this is a gen 2 issue?

Finally, I have had the R1S charging now for like 2+ hours and no errors or stoppages.

 

[Lester Green]

Thank you for sharing. That is very interesting. Curious how you got the UWC J1772 adapter out of the UWC and off the plug. I am not able to remove mine. The biggest way that I see my setup as different is that I am using polaris connectors in a junction box and not daisy chaining off the UWC. That is because I replaced a Gen 3 WC with the UWC and daisy chaining was not an option. I don't see how that would make any real difference though. It would be a huge and expensive hassle to change that cleanly.

 

[jrmbadger]

Thank you for sharing. That is very interesting. Curious how you got the UWC J1772 adapter out of the UWC and off the plug. I am not able to remove mine.

If I remember correctly, I removed the UWCs NACS plug (without the adapter), then reached over the regular wall connectors NACS plug (the cable was long enough given their relative locations) and plugged it into the UWC and pulled out the plug + adapter.

The biggest way that I see my setup as different is that I am using polaris connectors in a junction box and not daisy chaining off the UWC. That is because I replaced a Gen 3 WC with the UWC and daisy chaining was not an option. I don't see how that would make any real difference though. It would be a huge and expensive hassle to change that cleanly.

Yeah, I don't think that would be the issue. Looks like you have a GEN 2 vehicle though. I wonder if there is a difference in how GEN 1 and GEN 2 AC charging works?

Have you tried, as a workaround, setting the circuit to 50 amps? Perhaps the additional 6 amp headroom would allow the Rivian the time it needs to ramp down?

 

[Lester Green]

I do have a Gen 2 R1S. The circuit is set to 60 amps, max 48 usable.

 

[Time2Roll]

If the option to reduce was available it would seem the EVSE unit is limiting the power.

Are the two EVSE for sure communicating? Stuck at 24 seems like the communication could be broken and limiting each to half of 48 amps.

 

[303TP]

@Lester Green, update: I just went out to reproduce our shared issue (reminder, we have the exact same problem) and lo and behold, I can not reproduce it anymore. I tried everything, the Rivian would not fault out the UWC. With my MY not connected it was pulling 10.6 KW and upon connecting the MY, it ramped down to 5.5 KW. I tried this first with the MY not set to charge right away and then I tried again with the MY set to immediately start charging. The Rivian hung through all the ramp downs and ups.

The only change is the my R1T Gen2 updated to the latest software last night. Whatever the version is with Google maps. Interested to hear if you can still reproduce with the new software or if this bug is squashed.

 

[Lester Green]

After reading your post @303TP I was hoping this issue was behind me, but it is not. I removed the schedule from my R1S and began charging at 48amps. I then plugged in my Model 3 and the 7 red blinking lights error happened. I then unplugged and re-plugged in the R1S and charging resumed at the expected lower amperage.

 

[Supratachophobia]

Are you doing the serial connection?

 

[Lester Green]

Are you doing the serial connection?

I'm not sure what you mean by serial connection?

 

[Lester Green]

Random thought (mainly cause this happened to me last night). I've had issues occasionally where one or both of the Tesla chargers loses a wifi connection (no idea why, reception is quite good in the garage ). When this happens, each charger defaults to it's load sharing profile (i.e. 40A for me) for presumably safety reasons, since they can't communicate. It's easy to miss - the light on the charger will blink green very subtly.

No idea if this might be the case, but figured I'd throw it out there.

I think that is what was happening. Good call. There was a random WiFi issue. Connecting fine now and it can work at 48amp solo again.

 

[303TP]

@Lester Green , well I spoke too soon. Just got the 7 red flashes again per the usual.

 

[Lester Green]

Sorry to hear that, but I think it’s a good thing that the problem is consistent and repeatable.​

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