It’s early days in terms of working out the details around the Rivian R2 battery, but thought it might be worth just seeing what we know or could infer. The Rivian Investor Day 2024 [1,2] gave a lot of details around the updates to the R1 and this new smaller vehicle, but left a lot out.
If we count the bars and assume these relate to cells then we get 795. The obvious number is 792 cells as that would be 198s4p. Others [4] see this as 34 x 8 cells per module for a total of 272 x 3 = 816 cells, giving 204s4p.
An obvious solution is to run the three modules such that the positive and negative connection points are at the rear of the vehicle (right hand side of the image). This reduces the busbars inside the pack and with a 4p arrangement would result in 198s.
The 4p configuration fits very well with what appears to be an 8 cell wide module. The turnaround at the front of each module fits well with what appears to be an extended busbar. Plus we can see what appears to be a groove running down the centre of the module, starting just after the first row of cells at the front (left hand side of image).
The wheelbase is 2,935mm and hence we can scale the overall pack dimensions from this.
Cell
From the LG Energy [3] press release we know they have a 5 year deal to supply cells for the Rivian R2 and that these will be 4695 cells. At the moment we don’t know the specifications for this cell, but expect the capacity to be in the range 30Ah to 35Ah based on data from other cell manufacturers.
Pack Configurations
Using the Battery Calculations Workbook and the following parameters:
- Cell
- Nominal Voltage = 3.65 V
- Nominal Capacity = 32.5Ah
- Mass = 0.41 kg
- Pack
- Cells in series = 192s
- Cells in parallel = 4p
This post has been built based on the support and sponsorship from: Thermo Fisher Scientific, Eatron Technologies, About:Energy, Quarto Technical Services and Alvatek.
The total mass of cells would be 315kg and using the best fit trends for BEV’s this would give a pack that weighs 496kg.
- Pack total energy ~ 91kWh
Pack to Vehicle
At this moment the images show a very normal pack design. The investor day presentation [2] describes this as “R2 and R3 Floor-to-Pack Design Identical assembly fixtures, fore-aft alignment and common datum features”
The fore-aft structure in the pack would suggest that the cross-car beams are still there in the body structure.
Electrical
Some of the electrical sub-systems have now been pulled into the battery pack, similar to the Tesla Model 3 approach.
The power conversion on the rear of the pack also means that for the AWD version the power cables need to run from the rear of the pack to the front inverter and motor.
References
- 2024 Investor Day, Rivian
- Investors Events & Documents, Rivian
- LG Energy Solution to Supply Next-Generation 4695 Cylindrical Batteries to Rivian, LG Energy press release
- Rivian’s New Battery Cell Could Be Even Better Than Tesla’s, Motor1.com
See also: Benchmarking Battery Packs, Pack to System Mechanics