• Rivian CEO RJ Scaringe told reporters that an 800-volt architecture is “not as critical” for small and mid-size products like the R2 and R3.
• While other companies use higher-voltage architectures to provide better charge times, Scaringe says blazing charging speeds are possible with 400-volt systems.
• Given that the R2 is supposed to be cheaper and, ideally, more profitable for Rivian, it probably won’t use an 800-volt system.

Rivian has not yet announced whether its forthcoming R2 and R3 midsize cars will use a 400-volt architecture or a more expensive 800- or 900-volt system. Fans may be hoping that the next generation of products will move to a higher-voltage architecture, which typically can allow for faster charging and more efficiency. But after sitting down with Rivian CEO RJ Scaringe, I don’t think that’s likely.

In a roundtable with reporters, Scaringe said that while there are benefits to going 800-volt, they’re more important for bigger batteries. Larger packs—like those in the R1—are more likely to be voltage-constrained. But with a smaller pack like we’re expecting to see in the R2 and R3, Scaringe says battery chemistry is a bigger limiter than voltage.  

In the R2, the move is “just not as critical,” he said. “R2 we’ve optimized more around cost, to make sure we deliver great performance but [at] these price points. I don’t think it’s as important in a smaller vehicle.

He stopped short of confirming directly that the products would be on a 400-volt architecture, but he sounded quite convinced that an 800-volt system wasn’t necessary for R2 or R3. The larger R1 will “need to transition” to an 800- or 900-volt setup, he said, but didn’t say when. Such a substantial change is unlikely until the vehicle’s next redesign.

Hyundai, Kia, Lucid and Porsche have all been bullish on 800- or 900-volt architectures. Their cars show why the technology is appealing: A relatively affordable Hyundai Ioniq 6 can zip from 10% to 80% in just 18 minutes. A Porsche Taycan can do it in 16. That’s blazing fast. But Scaringe says that the focus on voltage is misplaced. While an 800-volt pack can deliver charging speeds of 350 kW or higher, in most smaller or mid-size vehicles the voltage isn’t the limiter.  

20

“We think ultimately the charge times need to be sub-20 minutes for that 10-80 time. We’re 100% aligned on that. You can get there with [400v],” he said. A 450-volt charger running at 500 amps can deliver 225 kW. If a car with a sub-100-kWh pack could sustain those speeds, it’d be capable of doing 10-80% in 20 minutes. Look no further than Hyundai for proof. Despite its 800-volt architecture, a Hyundai Ioniq 5 or Ioniq 6 will “only” peak around 220-230 kW. Some 400-volt cars like the Tesla Model 3 and Rivian R1 can hit similar numbers. The Hyundais just hold higher speeds for longer, allowing for those ultra-fast charge times.

But that shows that the voltage isn’t really the problem. Many existing battery packs just cannot accept that much energy for long enough to deliver those sorts of times. An 800-volt system would probably help, but cell chemistry and battery cooling is more important, Scaringe says. He didn’t mention it, but the implication is that its “4695” cylindrical sells the company plans to use in the R2 and R3 should have better thermals than existing batteries.  

We’ll see if they’re good enough to hit the sub-20-minute charge time goal. Right now, Rivian has only claimed that the R2 and R3 will be able to do a 10-80% charge in “under 30 minutes.” Getting to a sub-20 time is a much tougher challenge. Given that Scaringe noted it as a long-term goal rather than a promise, there’s no word on whether the R2 or R3 will get there. If they do, though, it likely won’t be with the help of an 800-volt architecture.

Contact the author: [email protected].