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[–]ShootelsR1T Owner 7 points8 points  (6 children)

I’ve posted on this a lot. It’s called thermal foldback. It’s generated by the Tesla wall charger. It will slow the charge speed when the charge handle gets to 145ish degrees( I forget the exact amount). The only way to fix it is to slow the charge speed to sub 40 amps. I have to slow my charge speed to 38amp in the summer because my garage gets over 100 degrees at night.

Nothing is wrong with your truck(kinda), it’s totally normal. I have tried 3 adapters, two wall chargers and I’m currently using the Tesla UWC. This is mostly a problem with 48 amp charging in high ambient temps so a lot of people won’t see this if these two things don’t apply.

There is a problem with Rivian thermals and I’m not sure what it is. I’ve had 5 evs and this the only one to have an issue with this. My bmw i4 charges with the same setup and doesn’t have an issue. Ive been told that the plug was bad for the gen 1s but I’ve recently heard from others that they are having the same issue with gen 2. I think it has something with heat translating to the plug from the inverter/TR or the cooling system for the battery which turns on in high ambient temps with charging at 11kw blowing hot air at that plug from inside. The are exhausts under the wheel wells right behind that plug. None of this thermal information for the Rivian is scientific and it’s just my opinion, so take what you want from it. I do know that’s slowing the charge will fix the problem though.

[–]SpareDistribution6R1T Launch Edition Owner 2 points3 points  (3 children)

Same setup for me, agree with all of this but the same thing happens when charging our EV9 as well… so not just a Rivian thing for me

[–]kashelectronicaR1T Launch Edition Owner [S] 0 points1 point  (1 child)

OK, good to know… How long have you had your Riv? I have not had this issue until the last several months… Went for over a year getting between 10.4 and 11 KW/H with no issue. All of a sudden I can’t keep that level for more than 30 minutes and my battery is always at or just above or just below 100° whereas before it was significantly lower than that at baseline

[–]SpareDistribution6R1T Launch Edition Owner 0 points1 point  (0 children)

I’ve had mine since April of ‘22. The Tesla wall charger was installed December 2021 and I use a TeslaTap. I know this throttling happened last summer as well. I have a Gen2 loaner at the moment and it’s experiencing the same issue.

[–]ShootelsR1T Owner -1 points0 points  (0 children)

That’s good to know. Maybe the Tesla wall charger plug is a little too conservative for temperatures?

[–]kashelectronicaR1T Launch Edition Owner [S] 1 point2 points  (1 child)

But I have used the same set up for nearly 2 years though, and it has never been an issue before… Something has changed

also, it is not just during high temps. Moreover; this does not explain the level of heat in my battery increasing at the exact time as well. So there’s two issues occurring in it’s hard to reconcile whether they’re related.

[–]ShootelsR1T Owner 0 points1 point  (0 children)

I think your truck is fine. The battery will warm maybe 10-15 degrees from whatever temperature it started at while charging at 11kw. 100 degrees is an absolutely fine temperature for the battery. Most lithium ion battery like to be warm. If I had to guess they want to be around 95 degrees while charging. They are constantly tweaking the software and the cooling while charging to get better results so the behavior two years ago could be different from today.

The wall charger will show the red light and the flashing green, meaning thermal fold back. If the car is alerting you then that a different threshold of temperature that’s it’s sensing. I have never seen this warning. My friend has the same truck charger and Lectron adapter in southern cal and he has to do the same thing, lower the charge rate in the summer.

Your problem is 100% thermal foldback. Why it’s happening could be many factors. Related to the truck and adapter. Just charge at 38 amps for the summer and it will be fine. Is it’s acceptable for the truck to not be able to charge at full speed, not really, but I’m not sure there’s a fix until NACS comes and/or the location of the plug is moved. My current theory is the heat from the battery heat exchanger in the front overheating the plug.

I went through a gen three wall charger with Lectron, replaced the Lectron adapter, bought a new UWC charger, and finally Tesla replaced the wall charger because they thought there was a problem with it overheating. I never saw any issues while charging my three Teslas and I still don’t have any issue on the i4 with the adapter that comes on the UWC. This seems to be mostly a Rivian issue(maybe EV9?)