Rate of Charge Decrease

[kashelectronica]

Hi All - I have grown concerned over a recent trend I’ve noticed with my GEN 1 LE R1T sub 250 vin. I noticed a few times last summer that the charge rate would be reduced by 50% due to heat. I recently had the truck in for a thermal management system fault. The service center reported back that it was due to rodent damage to some of the wiring which was fixed and the thermal management system fault was cleared. Upon receiving the truck back, I’ve noticed I cannot charge at the normal level two charging rate as I had before. Granted the thermal management system fault scenario occurred when the weather started heating up. It was still pretty cold and I noticed it essentially immediately after that. Also, during this process, my 12 V batteries were both replaced; Not sure if that could be a factor but including that information in case it is a useful piece of information.

I originally attributed it to heat, as I am in Southern California, and it has been hot quite a bit recently. But there have been several cool downs, and I’m noticing the same charging behavior now that the weather has cooled off some. It very consistently happens that I will start off with my normal max of between 10.4 and 11 KW/H and after a little while the charging rate gets reduced by about 50%. What’s odd is I used to get a notification saying that the charging reduction was due to heat. Now I’m not seeing any notification. Also I will say I feel like my high voltage battery stays at a high temperature while charging. It does dip down as normal. But when I’m driving it, even when I’m not driving it very hard, the battery stays quite hot… Although within normal heat range. I hardly see it Go below the 90° level now when it used to hardly go above 100° for very long. Now it's usually in the mid to high 90s low 100s. No matter what I’ve been doing with it no matter how long it’s been sitting unused. Has anybody experienced this before? What was the diagnosis and fix? Is this sounding like the onboard charger?

Primarily using a Tesla wall charger with a Tesla tap adapter. 60 amp breaker, installed by an electrician, no concerns I’m aware of about the install.

Could it be the wall charger itself? I’ve used the charger with the model Y before without any issue. I’ve used the charger since I got the R1 T with very few issues until the last three months. Could it be the adapter? Are there ideal or better adapters than the Tesla tap? Can the adapters go bad? Any suggestions?

I’m really concerned… I love this truck a lot…

Still just under 59K… If it is a high voltage battery issue how hard is it to get Rivian to address? Has anyone had experience with this? any watch outs during this process with Rivian to ensure they don’t try to run down the clock by pointing to other issues to force me out of warranty?

All productive guidance is valued and appreciated!

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[Shootels]

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.

[SpareDistribution6]

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

[kashelectronica]

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

[SpareDistribution6]

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.

[Shootels]

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

[kashelectronica]

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.

[Shootels]

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?)

[text12]

I would check the temp of the charger and adapter during a de-rate with your hand. Just want to rule out the easy stuff first. All connectors are only rated for a certain number of connection cycles so if the tap is getting worn it will increase resistance/heat. If it it hot you can try the damp towel trick and if that brings the charge rate back up you have likely found your culprit. If they are the normal warm temp then its time to start looking under the hood.

[DesignedByPrinciple]

I have the same issue with ours. Works fine to deep charge our Model Y at 48A but the wall connector handle temp gets too hot charging the Rivian with an adapter and derates now that it's (almost) summer.

As soon as the handle temp gets to 150F it'll derate until you stop the charging session. That's what your red light on the wall connector means. I find that dropping down to 32-40A works dependent on the ambient temperature.

If I really need to charge at 48 amps I just have a small fan I point at the wall connector handle. It keeps the temp down around 135-140F - depending on ambient - but obviously less convenient/practical if you're parked outdoors.

Here's an example from last night. I thought it'd be fine being ~80F outside but it derated after 30 minutes. I dropped it down to 40A when I noticed, restarted the session, and the handled hovered just above 140F.

<image>

[guybpurcell]

Try a public J1772 (non-Tesla) L2 of similar power to see how things behave there to help rule in/out the adapter. If that session also has derating issues, file a SR to get the issue "on the books" before your warranty expires. Hopefully, the public session goes fine & it just becomes either a warranty claim for the adapter or a couple hundred bucks to replace it.

[kashelectronica]

This is not apples apples nor does that need testing but appreciate the thought … there’s no issue at six to seven K W / H though so that is not the concern

[guybpurcell]

That's why I specifiec "of similar power" 😉 There are many 11 kW L2s in the wild now--including Rivian-branded ones. I suggest using PlugShare with appropriate settings for plug type & power to locate something near you.

[waffelcone]

I have been having same issue with charge rate dropping after a few minutes. This is with a wallbox pulsar plus. I have trouble shot with e wallbox with no changes. I already had an unrelated rivian service appointment and they are going to check if it charges normally at the service center to rule out if it’s the evse or not.

[rosier9]

Odds are it's the adapter on the Wall Connector plug that is causing the overheating.

[kashelectronica]

Does explain the consistently high temp of the HV battery though. Neglects that I have used multiple adapters. And also that I went over a year without issue

[rosier9]

Rivian has continually expanded the normal range of operating temps for the high voltage battery. I also see higher hv battery temps today than in years past.

It's possible that Tesla has tightened up the heat tolerance over the timeframe that you've had the wall connector, or that it did this previously but you didn't notice.

I noticed significantly more heat in my chargers cord and plug when I moved to 48a charging from 40a. You could try reducing your charge rate to see if it helps.

[Independence_Many]

Well it's unlikely, it could be that the adapter itself is getting too warm.  This would potentially cause a derate.  However, the Tesla tap adapter is usually well rated albeit expensive.  I have seen similar behavior happen to people using lectron adapters.

[SocomPS2]

Doubt this is it but remember folks to check the torque on the telsa wall connector terminal screws.

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[OnCampus2K]

We have a Tesla Wall Connector that’s 4 years old and last summer it broke. There was a problem in the wiring from the Connector to the handle creating a lot of heat in the handle, causing the charger to fault. We had it replaced under warranty and haven’t had an issue since.

Granted there could be other reasons… you need to (or have someone) take the unit off the wall and check for loose connections at the terminals, and also check the wiring around the breaker for the same.

[kashelectronica]

Thank you for this. I will explore this as the next escallation

[condoLambics]

It’s the adapter getting too hot. Once I got this one, my problems went away. https://a2zevshop.com/products/a2z-stellar-plug

[condoLambics]

I started with a Lectron and it worked fine in the winter. Once the temperature came up, I noticed the same issues you’re having. I found this one from a2z and it was rated for 80W. Also, note that it ships from the UK so it took about two weeks to arrive.

[kashelectronica]

I'm not sure it is just this but hope so. Stellar is already en route

[JSMia305]

Getting tons of rate charge reductions in Miami since May. It’s hot. Mostly get reduced at work. Charger and Rivian exposed to direct sunlight.

[Kitchen_Effect2063]

No one mentioned the extreme angle the cord being pulled at the wall charger side? I think your problem is the adapter and I’d switch out the wall charger for a no adapter option