An update on the Rivian R2 battery pack, now we have more information and more hard data.
Trouble is the 2024 Investor Day R2 data left out a lot of the detail and the CEO updates in 2025 (Rivian R2 Pack – 2025 Update) were a little bit confusing.
Time to again see if we can build a more complete picture with the latest references.
Metrics
- Energy Density
- Gravimetric = 167 Wh/kg
- Volumetric = 239 Wh/litre
- Power Density
- Gravimetric = 1005 W10s/kg
- Volumetric = 1380 W10s/litre
Specifications
- Usable Energy = 87.9 kWh
- Total = 94 kWh
- Usable SoC Window = 93.5%
Officially EPA certified the usable energy at 86.8 kWh. Energy Buffer: Certified EPA depletion testing recorded a total depleted energy of 88.7 kWh, indicating a 6 to 8-mile physical energy buffer built into the pack design after the driver’s state-of-charge indicator reaches zero percent to prevent immediate immobilization and protect cell health
- Nominal Voltage = 353.3 V
- Nominal Capacity = 266Ah
- Discharge
- Peak Power = 543 kW10s
- Charge
- Peak Power = 230 kWfast
- Peak Current = 630 Amax
- 10 to 80% SoC = 29 minutes
- Pack Mass = 541 kg
- Pack Volume = 394 litres
The Rivian Engineering Team describe the battery pack design in the Munro Live [2] youtube video.
Moduleless Architecture: The R2 platform utilizes a moduleless Cell-to-Pack (CTP) structural integration method with an inverted tub enclosure. Rather than isolating cells inside protective modular boxes, the battery pack casing is engineered as a primary load-bearing component of the vehicle’s chassis.
Pack Constants: The completed Long Range battery pack has a total mass of 541 kg (roughly 1,192 lbs) and a pack-level gravimetric energy density of 167 Wh/kg. Structurally, it is configured in a series-parallel layout of 97s 8p operating at a nominal voltage of 353 V to 357 V.
Cabin Floor Integration: The top sheet of the battery pack serves a dual purpose, functioning as the main physical cabin floor of the passenger compartment. This eliminates intermediate structural panels, saving 7 mm of vertical packaging space, reducing structural mass, and lowering the center of gravity to optimize ride dynamics.
Utilization of the 7 mm Space: The saved 7 mm of vertical space is utilized to provide more ground strike protection deflection space (allowing cost and weight to be taken out of the underbody package) and to add venting space in the pack (simplifying the venting strategy and minimizing pressure release valves).
The battery pack enclosure is an inverted tub design.
Potting Foam Encapsulation: The entire active cell volume is encapsulated in high-rigidity structural potting foam and adhesive. This securing medium protects cells against mechanical vibrations, reinforces the structural unity of the pack, and minimizes the propagation of thermal runaway between adjacent cells.
Non-Serviceability: This potted configuration renders individual cells completely non-serviceable. In the event of a localized cell failure, the entire core structural pack must be replaced as a single unit.
Collision Load Management: Frontal impact forces are managed through twin internal longitudinal structures engineered to deflect up to 120 kN of force. Side impacts are mitigated through a heavy-gauge inverted tub enclosure combined with designed air gaps along the outer frame rails to prevent physical deformation from reaching the cells.
This earlier 2025 image we have of the inside design of the battery pack clearly shows the longitudinal beams.
The castings align with this internal structure.
This earlier picture also shows that there are 3 “modules” or groups of cells, now this is described as “moduleless” but they also describe the longitudinal beams. Hence this earlier image must be close to the production structural design.
These may not be modules, but this grouping of cells would make assembly easier.
The two front diecast mounts are each made from two separate castings.
In the Munro Live video [2] they suggest this two part approach is required to allow them absorb the tolerances between the battery pack and body structure.
Note the features in the castings that would allow the detachment in a front end crash. They say this allows the structure to deform further and absorb more energy.
This post has been built based on the support of and sponsorship from: illumion, Custom Power, Quarto Technical Services, Eatron Technologies and About:Energy
As yet we don’t have independent cell specifications and the values given below are reverse engineered from the battery pack data declared to the EPA.
Cell Specifications
- Manufacturer = LG
- Chemistry = NCMA
- Format = Cylindrical 4695
- Nominal
- Capacity = 33.3 Ah
- Voltage = 3.64 V
- Energy = 121 Wh
Finally benchmarking this pack against the competition we see that it is around middle of the road for cylindrical cell based packs.
References
- EPA Applications
- Rivian’s R2 Structural Battery Pack Explained by the Engineering Team, Munro Live, YouTube
See also: Benchmarking Battery Packs