12v replacement required on new gen2 R1T

[wash_chris]

I picked up my 2026 gen2 R1T tri max on 10/18 and I’ve put 420 miles on it since then. I have a short daily commute and use it for local errands so the truck will never see a lot of miles. I’ve charged about once a week up to 85%. I do not stay plugged in to the charger at all times, but don’t ever get below 50%. Last Saturday I had to leave for a week long business trip, and charged up to 90% before leaving. Sunday morning I got the ‘Replace 12V Battery’ error in the app, with the main battery sitting at 88%. The mobile service is coming out to replace the battery, so this is annoying but it is handled.

My question is - this is probably a fluke, but is there anything I should be doing differently to avoid this or other battery issues?

I’ve since disabled gear guard and proximity unlock at home, which were both on. Should I just stay plugged in whenever at home? Will that matter?

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[BigE]

I picked up my 2026 gen2 R1T tri max on 10/18 and I’ve put 420 miles on it since then. I have a short daily commute and use it for local errands so the truck will never see a lot of miles. I’ve charged about once a week up to 85%. I do not stay plugged in to the charger at all times, but don’t ever get below 50%. Last Saturday I had to leave for a week long business trip, and charged up to 90% before leaving. Sunday morning I got the ‘Replace 12V Battery’ error in the app, with the main battery sitting at 88%. The mobile service is coming out to replace the battery, so this is annoying but it is handled.

My question is - this is probably a fluke, but is there anything I should be doing differently to avoid this or other battery issues?

I’ve since disabled gear guard and proximity unlock at home, which were both on. Should I just stay plugged in whenever at home? Will that matter?

I think the best rule of thumb is ABC. Always be charging, or what I mean is, if the truck is home, plug it. We keep ours daily at 60% SOC in the summer and 70% in the winter. We're on our 2nd R1T and have 34k on this one. Rivian did a proactive 12v replacement this past summer on ours. Someone else will chime in, but the 12v in these EV's is pinged a lot, a lot more that a ICE vehicle. And, if I'm thinking right and I can't recall why, it's better to have it plugged in to help maintain the 12v. Also, there is a lot of data for battery life, if you can keep an EV between 40-50 or 40-60% daily, will extended the life compared to say charging to 85% and running it down to 20% before charging again. Dr. Jeff Dahn has done a ton of research on this topic.

 

[electruck]

likely just a bad 12V, or possibly even just a bad electrical connection. nothing you should be doing differently at this point.

I had a proactive 12V replacement after maybe 2 years of ownership. They replaced both 12V (early Gen1 have 2 batteries). About 3 days later, I got another alert that the 12V needed to be replaced. One of the 2 brand new batteries was faulty. They replaced the bad battery and double checked all the connections and everything has been fine since.

 

[defcon888]

I picked up my 2026 gen2 R1T tri max on 10/18 and I’ve put 420 miles on it since then. I have a short daily commute and use it for local errands so the truck will never see a lot of miles. I’ve charged about once a week up to 85%. I do not stay plugged in to the charger at all times, but don’t ever get below 50%. Last Saturday I had to leave for a week long business trip, and charged up to 90% before leaving. Sunday morning I got the ‘Replace 12V Battery’ error in the app, with the main battery sitting at 88%. The mobile service is coming out to replace the battery, so this is annoying but it is handled.

My question is - this is probably a fluke, but is there anything I should be doing differently to avoid this or other battery issues?

I’ve since disabled gear guard and proximity unlock at home, which were both on. Should I just stay plugged in whenever at home? Will that matter?

We have the Gen1 R1T. At about 10 months I was driving to work and got the 12v battery issue. I called service at 4am and they answered. We tried the hard reset and a soft reset and didn't fix the issue.

Since I commute 145 miles to work and stay locally for a few days, he told me to close down the app all together after I have it parked, charge normal (we have chargers at work) and when you go to get in your car, to let him know if it resolved. I did all those things and itstill wasn't recolved.

When I went to the hotel to stay, I parked the truck and when I got in it the next morning.....voila.....it resolved itself. They still sent out a mobile tech to the house and he said "yeah, the battery is just OK, but I will replace it anyways". SInce March of 2024, haven't had any issues.

The 12v battery issue is a known thing on our trucks....didn't think it was still a thing on Gen2's.

 

[Rade]

I got a call back in July that they wanted to replace my 12v battery as a "precaution", and it was covered under warranty. The tech came to the house to perform the service and was done in less than an hour. I've had no issues prior to or since.

 

[iowa_don]

I picked up my 2026 gen2 R1T tri max on 10/18 and I’ve put 420 miles on it since then. I have a short daily commute and use it for local errands so the truck will never see a lot of miles. I’ve charged about once a week up to 85%. I do not stay plugged in to the charger at all times, but don’t ever get below 50%. Last Saturday I had to leave for a week long business trip, and charged up to 90% before leaving. Sunday morning I got the ‘Replace 12V Battery’ error in the app, with the main battery sitting at 88%. The mobile service is coming out to replace the battery, so this is annoying but it is handled.

My question is - this is probably a fluke, but is there anything I should be doing differently to avoid this or other battery issues?

I’ve since disabled gear guard and proximity unlock at home, which were both on. Should I just stay plugged in whenever at home? Will that matter?

I have a 2025 R1S Dual Motor Max Pack. I left for a five week trip to Norway and London at the beginning of October. I left my Rivian connected to the charger at 41% SOC and a charge limit of 50%. It charged to 50% and then every couple of days it would drop to 49% and charge back to 50%. Came home to a happy truck and no problems.

 

[UnsungZero_OldTimeAdMan]

I picked up my 2026 gen2 R1T tri max on 10/18 and I’ve put 420 miles on it since then. I have a short daily commute and use it for local errands so the truck will never see a lot of miles. I’ve charged about once a week up to 85%. I do not stay plugged in to the charger at all times, but don’t ever get below 50%. Last Saturday I had to leave for a week long business trip, and charged up to 90% before leaving. Sunday morning I got the ‘Replace 12V Battery’ error in the app, with the main battery sitting at 88%. The mobile service is coming out to replace the battery, so this is annoying but it is handled.

My question is - this is probably a fluke, but is there anything I should be doing differently to avoid this or other battery issues?

I’ve since disabled gear guard and proximity unlock at home, which were both on. Should I just stay plugged in whenever at home? Will that matter?

There were many posts about this some months back. Rivian discovered the tie down bracket were either out of spec or were torqued down improperly, thus putting too much pressure on the 12V enclosure and compromising its ability to hold charge. The launched a service campaign to replace all brackets and batteries. Yours probably slipped through that effort. Forum search and web search the topic, you will likely find additional info including communications owners received from Rivian.

Once 12V fails to hold and deliver charge there isn’t much more you can do, since it is essential for booting up all computers that run everything. Before that happened, Rivian’s recommendation is to keep vehicle plugged in to a home/mobile charger to ensure steady power supply… so that even at diminished total capacity, the 12V has better chance of having enough power to boot all systems and operate all door locks.

If the 12V gets so weak that vehicle becomes unresponsive, it’s possible to jump it with a jump pack. This information is in your Owner Guide and the Tow Operator Guide. https://rivian.com/support/vehicle-docs

 

[babock]

My 2025 Gen 2 R1T is at the service center as we speak to get the 12V battery and clamp replaced.

 

[jjrivian]

I have an earlier Gen 2 R1S . When going in for warranty repairs 4 months ago that wasn't related to a battery issue. They proactively replaced my 12v battery and clamps. I didn't have any indication of battery failure and they didn't mention why the replacement, but I assume they had a bad batch that needs attention. Maybe yours is one of them.

 

[UnsungZero_OldTimeAdMan]

Just one of many such threads from summer: https://www.rivianforums.com/forum/...-service-regarding-12v-2025-r1t-trimax.48805/

 

[llninja]

We have the Gen1 R1T. At about 10 months I was driving to work and got the 12v battery issue. I called service at 4am and they answered. We tried the hard reset and a soft reset and didn't fix the issue.

Since I commute 145 miles to work and stay locally for a few days, he told me to close down the app all together after I have it parked, charge normal (we have chargers at work) and when you go to get in your car, to let him know if it resolved. I did all those things and itstill wasn't recolved.

When I went to the hotel to stay, I parked the truck and when I got in it the next morning.....voila.....it resolved itself. They still sent out a mobile tech to the house and he said "yeah, the battery is just OK, but I will replace it anyways". SInce March of 2024, haven't had any issues.

The 12v battery issue is a known thing on our trucks....didn't think it was still a thing on Gen2's.

Last time I had mobile service the Rivian technician filled me in on the 12v issue, and they are different between Gen 1 and Gen 2. With Gen 1 the battery was too small so they had to modify the bracket and install a bigger one. For Gen 2 the high voltage to low voltage converter is much better so the battery is actually a smaller motorcycle battery, but the bracket they used to hold it in was cutting into the plastic battery case from vibrations so they replace the battery and a replace with a redesigned bracket to better hold it in place.

 

[UnsungZero_OldTimeAdMan]

Last time I had mobile service the Rivian technician filled me in on the 12v issue, and they are different between Gen 1 and Gen 2. With Gen 1 the battery was too small so they had to modify the bracket and install a bigger one. For Gen 2 the high voltage to low voltage converter is much better so the battery is actually a smaller motorcycle battery, but the bracket they used to hold it in was cutting into the plastic battery case from vibrations so they replace the battery and a replace with a redesigned bracket to better hold it in place.

Gen 1 issue was BMS software, both single and dual 12V examples, allowing 12V to discharge too far and not flipping contactors soon enough to replenish it with HV pack. The deeper discharges and the repetitive cycles is what ruined them. BMS was addressed through OTA. 12V replacement was then handled through a customer satisfaction campaign (aka TSB).

 

[sherold]

My question is - this is probably a fluke, but is there anything I should be doing differently to avoid this or other battery issues?

I’ve since disabled gear guard and proximity unlock at home, which were both on. Should I just stay plugged in whenever at home? Will that matter?

No, not a thing you should be doing differently. Probably not a fluke as it is a known design /process issue The truck completely manages the charging of the 12V battery, not you.

Disabling gear guard and prox unlock can help preserve battery levels but, won't cause or prevent your 12V batteries from failing.
Staying plugged in at home is up to each individual. It would not have changed anything in your situation though. I NEVER plug in at home unless I need to top off before a long trip or, do a lot of extra traveling over the weekend. My charging strategy is based on the fact that I charge every day at work though.

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