The largest Rivian battery pack, dubbed the Max pack, is now entering production, but with less capacity than original discussed.

When it announced the Max pack about two years ago, Rivian mentioned a gross capacity of 180 kwh. But this past week, Rivian confirmed to Car and Driver that it’s largest pack has a gross capacity of just 149 kwh.

Since then, Rivian has also confirmed that number to Green Car Reports as well as something perhaps even more meaningful: why it’s not 180 kwh.

In short: The Max pack utilizes a new battery cell, in the same form factor used by Rivian’s 135-kwh Large pack and without gaining mass—so with its greater efficiencies it may truly be worth the $10,000 premium.

“This efficiency was reached by our engineers who developed a proprietary battery management system that optimizes and increases the usable battery energy from a new version of our 2170 battery cell with advanced chemistry that allows for both higher energy density and higher absolute energy,” explained Rivian, in a response provided to Green Car Reports. “This is instead of adding more cells or modules to an existing battery pack, which would add more mass to the vehicle itself.

Rivian on Friday again confirmed that the total (gross) capacity of its Large pack is 135 kwh. Usable capacity, Rivian has emphasized in the past, may vary over time as it improves the electric trucks’ performance and efficiency via over-the-air updates.

“Our vehicles’ range is driven by many factors across energy storage, drive unit efficiency, aerodynamics, and more,” said a Rivian spokesperson to Green Car Reports Friday, in response to a query about current usable capacity. “As you know, we improve vehicle software through over-the-air updates, meaning we continue to optimize vehicle efficiency and range regardless of when a customer takes delivery of their Rivian.”

More miles per kwh for Max pack?

Without knowing usable capacity—and assuming it’s about the same ratio of the pack capacity as for the Large pack—that suggests the Max pack models are actually getting better efficiency and more miles per kwh.

The Max pack is available in both the R1T electric pickup truck and R1S SUV, but only with the recently-launched Dual-Motor powertrain. As revealed recently, the Max pack R1T and R1S have been EPA-rated at 410 miles and 400 miles respectively. Dual-Motor trucks with the Large pack were recently rated at up to 352 miles.

Allowing that three-row, 400-mile R1S Max pack

Deliveries of R1T Max pack models are already underway; R1S Max pack deliveries are scheduled to start later this fall—with its third row and cargo areas now likely not impacted by the Max pack.

That wasn’t originally the case. Earlier on in these trucks’ gestation, Rivian had suggested that packaging on Max pack R1S versions would be a bit different and forgo the three-row layout. 

Rivian has from the start used a different thermal strategy than other EV makers—allowing it to package more energy into less space. And it’s offered a battery warranty that beats Tesla and other EVs.

Now it’s clear they’re not done with these ideas and the longest-range trucks may represent improved thermal engineering. There’s surely more backstory to yet to come.

—
with additional reporting by Bengt Halvorson