12v Lead Acid Battery Replacement

[foxerson]

So, what is the actual strange replacement size for the battery? We can't be the only vehicle that uses this size. It has to have a designated name.

The Ohmmu website lists a group size of BT19BL-BS. This led me to a guess that an appropriate lead-acid replacement might be https://fullriverbattery.com/batteries/part-ft230d/.

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[True Brit]

So something like this...

 

[True Brit]

Or this...

https://www.walmart.com/ip/Yuasa-YU...-Maintenance-Free-Battery-YT19BL-BS/112826979

 

[DeafPug]

That Walmart link to the Yuasa YT19BL-BS looks to have a different style of terminal.

 

[Yota2R1T]

I was hoping that, when plugged in, the vehicle could determine when to suck some juice, depending on certain system needs. However, just plugging it in may not do anything, if it’s not part of a specific charging schedule. Dunno.

I have a home energy monitor and can see this is the case in colder periods. Energy use corrolating to the vehicle show up as 8-15min spikes periodically through sub-zero nights.
Now I'm on charging schedule, starting at 5:00am, which was not the case last year. Cold nights have just started, but I have not seen energy use, yet.
Hope that helps with some data/anecdotal.
R

 

[NY_Rob]

That Walmart link to the Yuasa YT19BL-BS looks to have a different style of terminal.

Yeah, the Rivian OEM batteries use a top post with the bolt hole running on the vertical axis. That Yuasa battery has the mounting holes running on the horizontal axis. You would need to make some sort of 90deg elbow to adapt the Rivian cable tabs to the Yuasa battery tabs. It's pretty tight in there with stiff heavy cables. Not easy to make mods in that particular location unless you're very motivated.

 

[PatientIsopod]

Another small update: On Friday, Rivian told me that they'd check the nearest service center for earlier openings. I still haven't heard back, unfortunately, which is a huge bummer because I've been constantly stressing about getting stuck and also have a road trip to Canada planned at the end of November..

The battery that @foxerson found is getting more and more enticing.

 

[PatientIsopod]

Good news, everyone! I'm happy to report that last week, Rivian found me an appointment at the nearest (but still kind of far) service center and today they replaced the 12v batteries under warranty.

Interestingly, while I was driving to today's service appointment (and still about 40 minutes away), a "system fault" was displayed. Obviously, this really spooked me in the moment but the truck let me continue driving as normal except with reduced acceleration and breaking. While I was getting off the freeway and dipped below 20mph, (luckily only .7 miles away from the service center), the truck would no longer accelerate above 20mph, and it also was no longer able to "hold" when stopped. I was able to make it that .7 okay, and told them about the new errors when I got there.

They checked it out and determined it was most likely the reduced voltage from the 12v that caused this fault. Rivian is going to give me a call in the coming weeks to ensure no other issues or errors have come up.

I'm very fortunate that my pestering Rivian worked to get me an earlier appointment, because it obviously wouldn't have made it until the mobile service appointment on the 9th.

Overall, I'm just happy to finally feel like I don't have to rush errands to get the truck plugged in again. Since these batteries are expected to last 2-3 years, next time this happens I'll probably give those non-OEM batteries a shot and order them as soon as I see any issues.

 

[mudito]

Amazing!

 

[Tucker74]

The major issue is they went with lead-acid deep cycles for cost savings. It seems they are discharging them too deeply and significantly reducing their usable life (if you discharge to 50% you get 450 cycles, where if you go to 70% you get 1250 cycles). I wish there was a LiFePO4 option like for RVs, they can be discharged 100% with little impact to lifespan. There are a couple options, but what I read here scared me away from the option (you really need a different charging profile). I reached out to Optima after they supplied these for the Pikes Peak trucks, but they wouldn’t sell them to me ?

 

[HotPocket]

And... After the DIY replacement, there's a service menu option to run the health check, reset, and diagnostics:
https://www.rivianforums.com/forum/threads/12v-lead-acid-battery-replacement.34985/post-643881

Do you know where I could buy this battery for a DIY replacement? Online, local, or wherever.

 

[mudito]

Do you know where I could buy this battery for a DIY replacement? Online, local, or wherever.

Not really. There are some who listed a few that might be almost a 1 to 1 replacement or there's also one provider selling lithium replacement (ohmmu) but those have mixed reviews.

 

[Rivianero]

If it helps others, I found this site that describes the battery group simply as "12v 18Ah". It has a list of several batteries from different manufacturers all with the same voltage and dimensions as the Rivian battery. SLA, AGM, and LFP (Lithium Iron Phosphate) versions are listed.

https://www.batteryequivalents.com/...12v-20ah-lithium-and-lead-acid-batteries.html

Exploring those from the list allowed me to identify still more similar batteries. Many of the LFP batteries have minimal BMS that would not make them ideal as a drop-in replacement for the AGM originally provided.

My 12v is shot from sitting too long without charging. The previous owner backed into a couple palm trees and smashed the rear bumper while perfectly denting both side panels and the tailgate. $52k in estimated repairs means insurance totaled it. It also means that I get a really nice fully-functional truck for a song. Unfortunately, Rivian informed me yesterday that my R1T (with 2300 miles on it) is deemed "out of warranty" since it was declared salvage. The truck was allowed to discharge completely from May until I received it in November. The high voltage system seems just fine but the 12v is irredeemable.

Rivian is requiring a $780 "salvage inspection fee" to make sure the HV system is safe enough for their mechanics to work on, before they could possibly replace the 12v battery (for which others say they are charging upwards of $800). Think I'm going to opt out of that madness and do a little more DIY by dropping in an LFP battery.

Others have pointed out the many potential drawbacks of swapping out the Rivian original battery for anything other than an their OEM deep cycle lead acid battery:

• The charging profile is most likely targeted for SLA or AGM, so it will not charge an LFP to full capacity or at an optimal rate/curve.
• Overcharge protection in a BMS may cause the Rivian to think the 12v has died.
• LFP has poor charging characteristics in below-freezing weather; BMS protection may cause the LFP not to charge and the Rivian to think it has died. Freezing weather occurs very rarely in my area of Texas.
• Since LFPs maintain relatively high voltage until depleted, the Rivian may not try to charge it until the LFP is near 0%. SLA and AGM batteries have more of a curve where voltage drops well before they are out of juice.
• The BMS in most good LFPs also provides over-discharge protection. Theoretically, the BMS in the LFP could decide that the battery is too depleted or some other fault condition and cause the battery to cut out suddenly. That could equate to a "dead stick landing" without instruments.

Nonetheless, the increased capacity and longer life of LFP over SLA or AGM is making me want to give it a go. I found one for ~$60 that claims to have a good BMS, 30Ah capacity, and several strong reviews. I recognize that this doesn't have all of the features purported to be in the Ohmmu LFP battery for Rivian, but the LFP I chose is a fraction of the cost and is readily available.

My late 2023 R1T has the 12v battery + capacitor arrangement instead of 2 batteries. I'm curious how that will play with a lithium battery. I imagine one reason the R1 platform design has dual batteries (or battery + capacitor) is for redundancy in the case of a single battery failure. Even in the event of a sudden battery fault (i.e., 0v output) I imagine the capacitor would provide enough juice to run instruments, bootstrap charging, or flip into a degraded but functional driving mode (e.g., turtle).

I'm just guessing, but I imagine that the really very smart R1 platform designers have included lithium batteries as an option and have not done anything in hardware that locks the R1 into lead-acid battery chemistry. The decision to go with deep cycle lead acid batteries (which I'm sure they probably now regret) was probably to reduce build cost or perceived higher reliability. It's a software-centric vehicle; there is probably code to support lithium profiles that has been commented out.

Will swap it out today and see how it goes.

 

[Rivianero]

OK, so I ended up dropping in this Lithium battery today as a replacement for the original failed OEM deep cycle lead-acid battery...

https://www.amazon.com/gp/product/B0D66QCB3L

So far, the battery warning has not resolved, however the vehicle drives normally and otherwise seems to function.

The geometry of the battery is slightly different than the OEM version:

• It is perhaps 5mm taller, making it difficult to secure with the original battery retainer.
• The M5 studs are located in slightly different locations on the top of the battery. This required a little creative rearrangement of the ground bracket and sensor, along with the positive side bus bar (red box). Not ideal, but it provisionally works.

I drove ~100 miles today and now have the system charging. Hoping that things may resolve overnight.

With some irony, I was informed by Ohmmu that their Rivian battery is now back in stock. Pricier than my little experiment, but far less expensive than what Rivian would charge for yet another lead-acid battery that might last 2-3 years.

 

[godfodder0901]

OK, so I ended up dropping in this Lithium battery today as a replacement for the original failed OEM deep cycle lead-acid battery...

https://www.amazon.com/gp/product/B0D66QCB3L

So far, the battery warning has not resolved, however the vehicle drives normally and otherwise seems to function.

The geometry of the battery is slightly different than the OEM version:

• It is perhaps 5mm taller, making it difficult to secure with the original battery retainer.
• The M5 studs are located in slightly different locations on the top of the battery. This required a little creative rearrangement of the ground bracket and sensor, along with the positive side bus bar (red box). Not ideal, but it provisionally works.

I drove ~100 miles today and now have the system charging. Hoping that things may resolve overnight.

With some irony, I was informed by Ohmmu that their Rivian battery is now back in stock. Pricier than my little experiment, but far less expensive than what Rivian would charge for yet another lead-acid battery that might last 2-3 years.

Did you try the 12v reset in the RIDE menu?

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