Rivian Has Hundreds of R1Ts Lined Up for Caltrans And Each One Gets a Hidden Battery Upgrade in the Spare Tire Compartment

There’s something exciting about watching Rivian quietly grow its presence in the real world, not through flashy announcements or press events, but through situations where someone sees something surprising and posts about it online. That’s how many of Rivian’s biggest developments surface, and I think that’s part of what makes the brand so interesting. You’ll be scrolling through a Facebook group, expecting the usual photos and range updates, and suddenly you’re looking at a story that reveals a much bigger shift happening behind the scenes.

Rene’s Post Uncovers a 600-Truck Caltrans Project 

That’s exactly what happened with a post from Rene in the “RIVIAN Electric Vehicles Discussion” group. Rene explained that Rivian is lining up another major fleet win in Sacramento, where the company is preparing roughly 600 R1Ts for Caltrans. Even more interesting, each of those trucks is being equipped with a hidden auxiliary battery pack installed inside the spare-tire compartment. “Great to see Rivian continuing to get huge contracts. Rivian in Sacramento, CA, is prepping like 600 trucks for Caltrans. Each truck has additional battery blocks installed in the entire spare tire compartment,” Rene wrote. It’s a single paragraph, yet it tells a huge story about how Rivian is stepping into state and commercial roles once dominated entirely by diesel heavy-duty trucks.

Why Fleets Need a Hidden Battery Pack 

This hidden battery addition immediately caught my attention because it shows that Rivian is tailoring its vehicles specifically for the needs of public service fleets. Caltrans trucks often run lighting equipment, radios, communication systems, work tools, emergency strobes, and digital signage for long hours. Running all of that off a standard 12V system or the main high-voltage pack isn’t always ideal. I think the auxiliary battery is Rivian’s way of making sure these trucks can power everything they need while still maintaining range and efficiency. It’s smart engineering and an even smarter way to prove EVs belong in major state fleets.

Real-World Experiences Show Why Rivian Fits State-Level Work 

When you look at Rivian’s track record, this kind of customization makes total sense. Over the past couple of years, Rivian has consistently proven that the R1T is one of the most capable EV platforms available today. We’ve seen owners push the truck through extreme heat and punishing terrain, like one driver who completed a 93-mile drive across Death Valley’s most remote road in 115-degree heat. Experiences like that demonstrate how robust Rivian’s thermal management system and powertrain really are. When a truck can handle scorching desert roads where even gas vehicles struggle, that’s a sign the engineering runs deep.

Rivian owners also tend to use their trucks as real tools, sometimes pushing them to limits most people would never imagine. One memorable example involved loading 8,000 pounds of river rock onto a trailer with negative tongue weight, and another owner took his truck on an incredible journey through nearly every U.S. state, completing a 49-state Rivian R1T road trip within a single year. These stories highlight why Rivian trucks are earning trust from agencies like Caltrans. They’re not just smooth city cruisers. They’re proven in real, demanding conditions.

Community Comments Reveal Practical Insights 

Even when Rivian’s service network hits bumps, owners still tend to praise the company’s engineering. In one case, a driver explained that a long Rivian service appointment revealed deeper concerns about quality control, but even then, the truck’s durability still impressed. And that’s important because public fleet operators care about reliability more than anything. If trucks can withstand everything private owners throw at them, then they can certainly withstand state-level use cases.

The reaction to Rene’s post also brought in some great perspectives. Robert jumped in and shared a memory that shows how quickly the EV truck world has changed. “Reminds me of the first 2 Silverado EV trucks I saw at Harris Ranch on my first West Coast EV trip I took down to Los Angeles for my nephew's wedding. They were relatively new EV trucks at the time,” he wrote.

Then Pa Teich added another perspective: “Ten years ago, I asked an Environmental Police Officer why he kept his truck idling at an event and was told that the flashing lights and radio would drain the 12-volt battery. My guess is that the extra battery block in these trucks will power the lights and radio.”

Finally, Santiago asked: “Additional battery blocks as in to extend the range? If so, I wonder why they need so much range? Awesome to see though!”

A Bigger Picture of Rivian’s Growing Influence 

The broader takeaway is that Rivian is positioning itself as a major player in government and commercial electrification. Stories like a 2026 Trimotor R1T order comparison that sparked new questions about ownership expectations show how Rivian evolves based on feedback, while huge state-level orders like this Caltrans project show that Rivian is no longer just a consumer brand. It’s entering the world of mission-critical fleet operations.

Moral Takeaway 

This Caltrans project highlights something important about EV development: the future of electric trucks isn’t just about range or performance. It’s about utility. When Rivian adds features like a hidden auxiliary battery pack for fleet operations, it proves that EVs can step into demanding professional roles and handle the work without compromise. And when a truck earns the trust of state agencies, it sends a powerful message to everyday buyers: if fleet operators can rely on it for long hours and mission-critical tasks, you can rely on it for your daily life as well.

Questions for Readers 

1. If Rivian offered an auxiliary battery upgrade like this for consumer trucks, would you consider it for work, camping, off-grid tasks, or daily driving?
2. Do you think state fleets adopting EV trucks will accelerate private adoption, or do you think buyers still need more real-world examples before making the switch?

Narek Hareyan is a young automotive journalist with experience in a golf cart dealership and an interest in the automotive industry. Follow Narek on X for daily news coverage about cars.

Image source: Rivian R1T Press Room, Renes Facebook Post on RIVIAN Electric Vehicles Discussion.