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

[macb00kemdanno]

I’ve been researching used R1Ts as a potential alternative to buying a new R2, and something that keeps popping up is 12V lead-acid battery failures. It seems as though there are three setups on R1:

• Two 12v (early Gen 1)
• One 12v + capacitor (later Gen 1)
• One 12v under the passenger seat (Gen 2)

All seem to have issues with deep discharges and premature failure from what I can tell, with some people opting for third-party solutions.

We currently have two Teslas (2023 and 2024), each with lithium low-voltage batteries, and have never experienced issues.

So does anyone know if R2 is using lithium for its low-voltage battery to avoid the R1 drama?

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[dradam]

While I have not had a failure of the 12V in almost 2.5 years of ownership I do watch this closely. I have seen no postings about Rivian going to Lithium. Some ownwer have swapped to Ohhmu Lithium but it seems that this has led to issues with warning codes because the charging curve is different.

There are postings that rivian will allow DIY battery replacement and a way to clear error codes after replacement, but nothing has shown up as of yet.

I keep a modified , charged 12V in my frunk and tools to get in the vehicle if my 12V dies unexpectedly, but await better options from Rivian.

 

[SadHill]

I have a July 2022 build LE and have never had a problem with the battery. Still on the original and when I bring it in for service I ask them to check it and they always say it is good.
I wouldn’t worry about the people who complain. The ones that don’t complain are the ones that don’t post.

 

[TTedP]

I’ve been researching used R1Ts as a potential alternative to buying a new R2, and something that keeps popping up is 12V lead-acid battery failures. It seems as though there are three setups on R1:

• Two 12v (early Gen 1)
• One 12v + capacitor (later Gen 1)
• One 12v under the passenger seat (Gen 2)

All seem to have issues with deep discharges and premature failure from what I can tell, with some people opting for third-party solutions.

We currently have two Teslas (2023 and 2024), each with lithium low-voltage batteries, and have never experienced issues.

So does anyone know if R2 is using lithium for its low-voltage battery to avoid the R1 drama?

For the 3rd bullet the issue was more of a bad bracket, cracked cases than electrical.

 

[JasonK]

I’ve been researching used R1Ts as a potential alternative to buying a new R2, and something that keeps popping up is 12V lead-acid battery failures. It seems as though there are three setups on R1:

• Two 12v (early Gen 1)
• One 12v + capacitor (later Gen 1)
• One 12v under the passenger seat (Gen 2)

All seem to have issues with deep discharges and premature failure from what I can tell, with some people opting for third-party solutions.

We currently have two Teslas (2023 and 2024), each with lithium low-voltage batteries, and have never experienced issues.

So does anyone know if R2 is using lithium for its low-voltage battery to avoid the R1 drama?

I agree. I personally don't see why they need a 12 volt battery when they can just use a inverter to change the voltage of the main battery to 12 volts. But I am not an electrician so assuming they need a 12 volt battery I do not see why they do not make one with the reliable Lithium cells they use to make the main battery pack. I have read way too many articles about Rivians with 12 volt battery issues.

 

[VandalSibs]

I agree. I personally don't see why they need a 12 volt battery when they can just use a inverter to change the voltage of the main battery to 12 volts. But I am not an electrician so assuming they need a 12 volt battery I do not see why they do not make one with the reliable Lithium cells they use to make the main battery pack. I have read way too many articles about Rivians with 12 volt battery issues.

Here's a nice write-up on why EVs still have a 12v battery. Essentially, it's to power all the components that are still 12v in the vehicle, and to isolate/disconnect the high voltage system when not in use (for safety and to keep as much energy in the HV battery as possible between drives).

 

[ElGuano]

Just my $0.02:

1. Inverters are energy-intensive to power constantly. That's why Rivian keeps it off by default for the 120v outlets. Leaving it on to constantly power a 12v battery would MASSIVELY increase phantom drain.

2. VandalSibs' point above about retaining power to LV systems when the high voltage line must be cut is a good redundancy factor to consider.

3. A huge manufacturing (and existential) point to the R2 is cost reduction. Would a fancy lithium 12v battery be cheaper than an equivalent SLA? I suspect the opposite.

4. Having a different chemistry doesn't strike me as immediately resolving the 12v failure issues. In fact, I would imagine lithium makes it harder. SLAs have a fairly linear voltage discharge curve, which is pretty easy to track. Lithium chemistries are flat, which is great for more consistent voltage delivery, but they have a "cliff effect" where everything looks fine until the last 5-7% when the voltage drops of dramatically, making it harder to track capacity level and health. You can have a sophisticated BMS with a current counter and tracker to manage this, but that adds to the cost and impacts #3 above.

So who knows, maybe R2 will come with an Li 12v, but I'm not sure what benefit it confers and what problem it solves, so I wouldn't be surprised if stayed SLA.

 

[VandalSibs]

I know that when Tesla went with Li-Ion low voltage batteries on the Model Y (right before I had gotten mine), they were actually 16v, which messed up the towing package, as the line that would top off the trailer batters (and power other accessories) didn't work. So that was annoying...

 

[Gen(R3)Xer]

I’ve been researching used R1Ts as a potential alternative to buying a new R2, and something that keeps popping up is 12V lead-acid battery failures. It seems as though there are three setups on R1:

• Two 12v (early Gen 1)
• One 12v + capacitor (later Gen 1)
• One 12v under the passenger seat (Gen 2)

All seem to have issues with deep discharges and premature failure from what I can tell, with some people opting for third-party solutions.

We currently have two Teslas (2023 and 2024), each with lithium low-voltage batteries, and have never experienced issues.

So does anyone know if R2 is using lithium for its low-voltage battery to avoid the R1 drama?

It better. I’m hoping the simplified zonal electrical architecture won’t cause as much vampire drain and recharging of whatever backup battery they end up choosing. There really is no need for lead-acid batteries in EVs. They just add weight and issues with discharging.

 

[Gen(R3)Xer]

So who knows, maybe R2 will come with an Li 12v, but I'm not sure what benefit it confers and what problem it solves, so I wouldn't be surprised if stayed SLA.

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.

 

[ElGuano]

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.”

I think the Rivian uses a 12v 18Ah battery. For SLA, that looks like it's less than 12lb:
https://www.1000bulbs.com/product/219352/BAT-10005.html
https://www.homedepot.com/p/MIGHTY-...-Battery-for-AGM-SLA1116-MAX3943617/326718238

To each his own, but to me, that's probably not going to be a leading factor.

 

[Alan in Tempe]

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.

 

[Gen(R3)Xer]

I think the Rivian uses a 12v 18Ah battery. For SLA, that looks like it's less than 12lb:
https://www.1000bulbs.com/product/219352/BAT-10005.html
https://www.homedepot.com/p/MIGHTY-...-Battery-for-AGM-SLA1116-MAX3943617/326718238

To each his own, but to me, that's probably not going to be a leading factor.

That is a tiny one. Maybe that’s part of the problem with the R1 batteries? Once Tesla switched to a lithium-ion backup and after they fixed some compatibility issues it seems like it’s all good. I haven’t had a problem. I think Hyundai has had similar problems with the 12V SLA batteries too.

 

[sparked]

So does anyone know if R2 is using lithium for its low-voltage battery to avoid the R1 drama?

I'm guessing lead acid 12v for R2 just because it's an easier supply chain. Even though I would prefer lithium ion.

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