Flaw in Gen 2 components

[Scoiatael]

2 weeks ago my 1 month old Gen 2 R1S's 12V battery died. It ended up getting towed to a service center. 2 techs spent 2 and a half days trying to diagnose the issue. Originally they thought there was an issue with the HV battery. But they could not find the problem and said isolation tests showed the HV battery was working properly.

Service center called me today to say they still don't know what the problem is, Rivian Engineers are attempting to diagnose the issue. They said there are other Gen 2s in their service center with the same problem. They wouldn't specify which module is the issue, and have no eta on a fix.

I don't know how wide spread this is, if it affects R1T as well, or any other configurations. I have a Large+ pack, not sure if its something related to that, even though its only a software locked Max pack.

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[norivian]

Sorry to hear that. My S max pk will turn 1 month soon. I don’t have the same issues as you.

 

[CharonPDX]

Considering all the problems the Gen 1 have with the 12V battery, I don't think this is a "flaw in general 2 components," I think it's likely a software thing killing 12V.

 

[sherold]

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[Scoiatael]

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This isn't an issue with the 12v. There is a module related to the HV system that is defective, and it caused the 12v to drain and the HV to go into safety mode. The fix for that module is what they are trying to figure out.

 

[bfilippo]

Sorry to hear this! I didn’t think any vehicles with Large+ were functionally Gen2? My understanding was all actual 2025 gen2 were standard, large or max packs? Maybe it’s to do with R1T gen2 shipping much later than R1S gen2?

Overall, just seeing way more issues on here with gen2 R1S than T, wondering if it’s purely anecdotal or if there are material differences making these issues manifest more often in the S.

 

[mpshizzle]

Sorry to hear this! I didn’t think any vehicles with Large+ were functionally Gen2? My understanding was all actual 2025 gen2 were standard, large or max packs? Maybe it’s to do with R1T gen2 shipping much later than R1S gen2?

Overall, just seeing way more issues on here with gen2 R1S than T, wondering if it’s purely anecdotal or if there are material differences making these issues manifest more often in the S.

Gen 2 Large + is just a software locked Max. No physical difference there. They were having delays with manufacturing the actual Large. So they briefly band-aided the situation by shipping Max packs with software lock to have the same capacity Large WOULD have had, and called it large +.

The reason you're seeing more about R1S than R1T is R1S has been shipping since June/July, R1T just BARELY started shipping so not many out there yet. It's a numbers game

 

[Scoiatael]

Its now been 4 weeks and they still haven't discovered a solution. My Connect+ plan expired today as well. The service center has been great at sending me updates, but each update is pretty much that they are waiting for Rivian Engineers to figure out the issue. I've told them I want to initiate a buyback if it isn't fixed soon.

 

[MountainBikeDude]

Its now been 4 weeks and they still haven't discovered a solution. My Connect+ plan expired today as well. The service center has been great at sending me updates, but each update is pretty much that they are waiting for Rivian Engineers to figure out the issue. I've told them I want to initiate a buyback if it isn't fixed soon.

Sorry about your current situation, but thanks for continuing to update the thread on how this is progressing, it helps others diagnose issues they may encounter, and helps bring visibility to issues and make Rivian a better company in the process.

 

[Scoiatael]

Got my R1S back from the service center yesterday. They ended up having an Engineer from Rivian fly out to figure out the issue. Turns out one of the modules that communicates with the BMS was defective. It was replaced and they ran tests to make sure everything is ok. My R1S was charged to 100% and I'm going to let it drain and not plug it in until I need to, just to make sure the 12V doesn't get drained again.

 

[Paul Hackett]

Got my R1S back from the service center yesterday. They ended up having an Engineer from Rivian fly out to figure out the issue. Turns out one of the modules that communicates with the BMS was defective. It was replaced and they ran tests to make sure everything is ok. My R1S was charged to 100% and I'm going to let it drain and not plug it in until I need to, just to make sure the 12V doesn't get drained again.

What's a BMS?

 

[Scoiatael]

What's a BMS?

Battery Management System, basically a small computer that handles everything related to the High Voltage battery and 12V battery.

 

[Paul Hackett]

Battery Management System, basically a small computer that handles everything related to the High Voltage battery and 12V battery.

I'm assuming that the 12v battery in the Gen 2 R1S is a Lithium Ion since it's in the cabin under the passenger seat. Would a battery tender protect against the 12v death drain? And even if a battery tender does protect against the death drain, I'm assuming that if you're unable to connect the tender due to travel or other circumstance then "you're" likely to get "humped" with this surprise potentially on the road. Any thoughts?

 

[Scoiatael]

I'm assuming that the 12v battery in the Gen 2 R1S is a Lithium Ion since it's in the cabin under the passenger seat. Would a battery tender protect against the 12v death drain? And even if a battery tender does protect against the death drain, I'm assuming that if you're unable to connect the tender due to travel or other circumstance then "you're" likely to get "humped" with this surprise potentially on the road. Any thoughts?

As far as I know the Gen 2 R1S uses the same AGM batteries that Gen 1 has. They just decided to move it to a more inconvenient place. There is a battery terminal in the frunk that you could hook up a battery tender to, but the BMS should be keeping it charged.

 

[NY_Rob]

I'm assuming that the 12v battery in the Gen 2 R1S is a Lithium Ion since it's in the cabin under the passenger seat.

It's a sealed 12V lead-acid battery, no need for venting due to it's AGM design. They haven't switched to Li-Ion yet.

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