Will the R2 have a lithium 12v battery (re: R1 12v failures)

[ElGuano]

I think there are a lot of affordable LiFe 12v 18Ah batteries available as drop-in replacements. Has anyone done this in their Rivian, and is there any way to tell if it's "better" or "worse" than the SLA? Not sure if anything has to change from a BMS/firmware perspective. I recall Rivian documentation holds that the 12v system should operate at 13.5v normally, spiking to 14.1v for LMV charging.

Sponsored

 

[zefram47]

There really is no need for lead-acid batteries in EVs. They just add weight and issues with discharging.

You will probably never see vehicle components using native HV for many reasons including safety as well as the current manufacturing parts base all using 12v components save for the Cybertruck using 48v, which still requires an additional battery(or batteries) and a DC-DC converter. Furthermore, when a vehicle's drivetrain isn't powered up, the HV contactors are opened for safety. To close those contactors, you once again need LV power, currently 12v. You're unlikely to ever see this changed and at-best we'd see a jump to a higher voltage LV system to allow running lower current, yielding smaller gauge wire, etc.

 

[mkg3]

SLA batteries suck compared to lithium.

“Lead-acid batteries are significantly heavier than lithium (LiFePO4) batteries, typically weighing 2–4 times more for the same usable capacity. A standard 12V 100Ah lead-acid battery weighs roughly 60–70 lbs, while a comparable lithium battery weighs only 20–30 lbs, offering about 55% weight savings.”

This matters to EVs especially.

“The self-discharge rate of an SLA battery is 5 times or greater than that of a lithium battery and they take longer to charge.”

Not good.

First, I'm not commenting on this particular post. Rather, this post is very typical of this forum so just using it as an example.

On one hand, people wants R2 LE to cost less than $55K, and the other hand wants this that and the other things that drive up the costs. 12V lithium battery cost significantly more than lead acid.

I have Li battery in one of my vehicle and while it's lighter and smaller than the 12v lead acid, it does drain faster.

 

[macb00kemdanno]

First, I'm not commenting on this particular post. Rather, this post is very typical of this forum so just using it as an example.

On one hand, people wants R2 LE to cost less than $55K, and the other hand wants this that and the other things that drive up the costs. 12V lithium battery cost significantly more than lead acid.

I have Li battery in one of my vehicle and while it's lighter and smaller than the 12v lead acid, it does drain faster.

Model 3/Y have been using them for about 5 years across 1 million+ vehicles globally, and they start as low as $37,000. Li low voltage batteries can’t be that much of a cost burden, especially when reliability goes up and you don’t have to waste service man hours replacing SLA batteries for customers.

Well-healed early adopter R1 owners that can afford $90,000 vehicles might shrug at a 12v failure and hop in their second or third car until they can get in for service. But mainstream buyers looking at an R2 don’t want that hassle IMHO.

 

[lefkonj]

Gen1 for 2 years then a Gen2 for the last year, never had a 12V issue. I get it there are problems but would be curious how wide spread they really are.

 

[crashmtb]

I would not want a lithium 12v battery, even in an EV, in winter. Unless it has its own lil heater.

 

[Gen(R3)Xer]

Model 3/Y have been using them for about 5 years across 1 million+ vehicles globally, and they start as low as $37,000. Li low voltage batteries can’t be that much of a cost burden, especially when reliability goes up and you don’t have to waste service man hours replacing SLA batteries for customers.

Well-healed early adopter R1 owners that can afford $90,000 vehicles might shrug at a 12v failure and hop in their second or third car until they can get in for service. But mainstream buyers looking at an R2 don’t want that hassle IMHO.

I agree. The whole constantly replacing your 12V SLA every 18 months is stupid. Here’s info on what Hyundai did to resolve their 12V battery EV issues. Seems like an even weirder problem than Rivian’s. I’m not that familiar with Hyundai EVs, but my coworker had her Ioniq 5’s 12V battery die on her twice before they finally replaced it.

“Hyundai has addressed the 12V battery drain issue in models like the Ioniq 5 by limiting Bluelink server traffic to 20 transactions per day and blocking unauthorized apps, which previously caused excessive battery draw. Additionally, they have replaced faulty Integrated Charging Control Units (ICCU) and their fuses in affected vehicles. Owners are advised to change their Bluelink passwords and ensure their vehicles are updated with the latest software to prevent recurrence.”

It’s time to move past this archaic tech in EVs. It’s like still having a cigarette lighter.

 

[SANZC02]

I have no issues with the lead acid batteries.

My Model S I have had going on 10 years, replaced the 12 volt 5 years in when the vehicle told me it required service. My guess is it might tell me to service it again on around the upcoming 10 year anniversary.

over 3 years with my R1S no battery issues so far, it has the dual batteries and I’ll replace them with the same when the time comes.

 

[Gen(R3)Xer]

I have no issues with the lead acid batteries.

My Model S I have had going on 10 years, replaced the 12 volt 5 years in when the vehicle told me it required service. My guess is it might tell me to service it again on around the upcoming 10 year anniversary.

over 3 years with my R1S no battery issues so far, it has the dual batteries and I’ll replace them with the same when the time comes.

Based on these forums you might be lucky. You don’t get any vampire drain, especially when using Gear Guard?

 

[Gen(R3)Xer]

I have no issues with the lead acid batteries.

My Model S I have had going on 10 years, replaced the 12 volt 5 years in when the vehicle told me it required service. My guess is it might tell me to service it again on around the upcoming 10 year anniversary.

over 3 years with my R1S no battery issues so far, it has the dual batteries and I’ll replace them with the same when the time comes.

You’re lucking out, or maybe it doesn’t affect as many people as it appears to.
I haven’t heard of Teslas having 12V battery issues, but there had to be some reason for them to switch Li-on.

I used to drive a Honda Fit and the original battery lasted for 7 years! Subsequent batteries never lasted as long. I think the brand must make a difference.

 

[SANZC02]

Based on these forums you might be lucky. You don’t get any vampire drain, especially when using Gear Guard?

No, I’ve never had any vampire drain issues. I was just out of town for 11 days, left at 80% and got back at 76% and I applied the last update while I was gone.

I’d say worse case (unless crazy hot in the desert) is 1% a day but usually it is less than 1/2 percent a day and seems to sleep well. This is in line with my Model S.

I have gear guard off at home but I can only set that at 1 location. When at my other place or while traveling gear guard does not seem to have much impact on drain.

 

[ElGuano]

No, I’ve never had any vampire drain issues. I was just out of town for 11 days, left at 80% and got back at 76% and I applied the last update while I was gone.

I’d say worse case (unless crazy hot in the desert) is 1% a day but usually it is less than 1/2 percent a day and seems to sleep well. This is in line with my Model S.

I have gear guard off at home but I can only set that at 1 location. When at my other place or while traveling gear guard does not seem to have much impact on drain.

~0.5% a day is what I get as well. I track the drain via HA integration when I'm on vacation, and the Rivian has always performed very well in this regard.

 

[Mathme]

I have had my battery replaced proactively by Rivian once in the past three years of ownership.

I too don't have an issue with lead-acid batteries as they are tried and tested technology. The problem is Rivian chose to put in a glorified motorcycle 18A battery into a vehicle with a high electrical load when it's sleeping. This high load requires a lot of charge/dis-charge cycles even when the truck isn't running. In this case, a larger, deep cycle battery would have been a better choice for durability but with all things, there's a tradeoff for that...

 

[MountainBikeDude]

Rivian actually filed a patent that uses a portion of the HV battery for low voltage components to eliminate the 12v battery from its vehicles in the future. If this makes it into the R2, it would be huge for both Rivian and consumers.

From
https://electrek.co/2025/09/26/rivi...ble-diffuser-screen-gadgets-new-architecture/


"Last but not least, Rivian submitted a third patent application for a BEV architecture design without any low-voltage batteries. This would alleviate the need for an EV’s 12V battery to power specific modules—dated tech that has affected the ability of several EVs across multiple brands to start up effectively. I drive an R1S and recently had my 12V battery replaced due to a recall. This design (which is far too complex and filled with jargon for me to grasp fully) would alleviate that reliance."

 

[Billyk24]

SLA batteries are great for high current discharge, as needed for non-EV starter motors, and bad at self-discharge and limited life. Lithium batteries are great for deep discharge, near-zero self-discharge, long life, and low weight. Cost difference is minimal at OEM pricing, due to high volumes, but significantly higher at retail due to much lower volumes. Lithium really is a great fit for the LVDC batteries in EVs, and Rivian should be using them if they value reliability for their customers.

As a Mach-e owner (on the R2 reservation list!), the 12V SLA is an issue for Ford, too. The common wisdom is replace the damn thing every 3 years regardless. When I requested the 12V be tested at the dealer at its 30K checkup just after 3 years (normally just tire rotation and safety inspections), I was told the 12V checked out fine. A couple of weeks later I had a dead 12V in my garage. The Mach-e forums are full of similar stories. If I have to wait more than a year for my R2, I will do another 12V replacement at the 6 year mark.

I must be one of the few who had 60 months ony 12v battery in my 2021 Mach E before putting a new one in.

Sponsored