Proactive Replacement of Rivian 12V Battery

Vincent · 2025-01-10T19:33:15+00:00

A friend needed to support his son who would be running a 'very cold' marathon on Sunday while rucking a 30 pound pack. The outside temps will be around 15F-20F the whole time. The location of the race is nowhere close to any L2 chargers, but he's not worried about driving distance to or from the race - it is 50 miles away from his house. He says he will be sitting in his ruck with his laptop and watching his live track+Garmin inReach data for the duration of the race (about 4 hours). He thought about taking his Honda EB2800i gasoline powered generator, if he can use the level 1 EVSE attached to the generator and keep the truck running with full heat + power - without really consuming much of the truck's main battery? He feels it's super dorky to have a gas generator running while attached to a Rivian in the woods, just so he can stay warm, but don't know if it would work ok this way and 'preserve' the main battery so he doesn't need to worry about driving range when we wants to head home. He talked to me about it and I told him the simple answer is NO. I tested this theory the other night when I was plugged into a 5.9kW charger. To maintain the interior amenities (interior and exterior lights, radio, heater, seat heaters), it took almost all of the charge. I charged for 15 minutes, it delivered 1.6kW, and the truck consumed 1.4kW, delivering only 0.2kW to the truck battery. Told him he would be using a laptop at another 200ish watts. The little trickle charger charges at 1.4kW on a good day, 1.2kW is normal for me. You can slow the bleed, but you cant stop it. My advise to him was for him to charge it up to 100% at home, and roll the dice is what I would do.

Rivian Mom

Active Wheeler

Jan 4, 2025

After reading the various reports of Rivian owners being stranded when their 12v battery died, I have been considering replacing mine proactively. I decided to ask Rivian to confirm if my R1S has one or two lead acid batteries. While support could not answer that question (after initially stating that all Rivians have 2 12v batteries), they suggest I let Rivian perform this service.

Was trying to book a service appointment when I found out that Rivian will only replace the 12v battery with a similar lead acid battery for about $300. I suspect this would be a foolish replacement. Instead, I'm considering replacing the 12v myself (well, with my handy brother's assistance) with a lithium battery. Don't know if I'll be making the right choice by replacing with a lithium battery in hopes of avoiding a dreaded 12v battery issue? Or perhaps the 12v battery issues are related to the build date? Maybe Rivian received a bad batch of lead acid batteries?

Talked to some owners and someone told me that the 12v batteries are a weak spot on these trucks. Advised that I souldn't spend all the money to proactively replace it. I sould instead purchase a good battery bank. If/when it fails, I can jump the R1S back to life and then replace them. The aftermarket lithium LifePo4 batteries are pretty good. One vendor claims to have heating. For me, as long as they have a bms and provisions to warm them up when it's really cold (LFP can be damaged by charging below freezing though they can still be discharged).

I believe this is a valid concern. Just better to be prepared if there is a failure because even if you spend the money to replace, there's no guarantee that you won't have a failure.

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