ajdelange

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@DucRider Curious if you saw a drag coefficient value for the R1T or R1S in this data you found? I did not see any and was curious how they would determine these number or if they are simple calculations of frontal area.
The manufacturer rolls the vehicle down an incline and from its speed and position vs time profile is able to determine coefficients a, b and c that determine the force F = a + b*v + c*v*v that retards vehicle forward motion as a function of its speed v. Those three coefficients are given to the laboratory that performs the test and are programmed into the dynamometer. Cd and A obviously influence a, b and c but so does rolling resistance.
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damn that cold weather number is scary. I know its an industry wide problem but wow.
 

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Major takeaways (from Rivian EPA application docs):
  1. Confirmed 108s pack architecture using 5A (nominal) 21700 cells. Modules are 8p yielding 40A ea. Nominal voltage of 400, max charging voltage of ~450V.
  2. DCFC Max of 210 kW
  3. Testing done in conserve and sport mode (then averaged)
  4. Conserve mode absolutely disconnects rear motors
  5. Tesla method of brake pedal only engages friction brakes. Blended braking mapped to the accelerator pedal if brake hold enabled. Since the accelerator should be lifted when braking, using max regen mode will recovery the most energy when using the brake pedal.
  6. Cold weather looks to be a ~40% range hit
  7. Useable battery kWh appears to be ~129
From the docs:
  • Every vehicle which is covered by this application conforms to US EPA Federal Tier 3 Bin 0 regulations applicable to new Medium Duty Passenger Vehicles and state of California ZEV regulations applicable to new Medium-Duty Vehicles for the 2022 Model Year.
  • Maintenance schedule:
    1632852921609.png
  • 4 motors, full torque vectoring capability with 1 motor/gearset per wheel. Drive units are packaged inboard, with priority on maximizing half shaft length to each wheel to enable maximum durability and suspension articulation.
  • Front and rear drive units have high level of commonality. The motor, gearbox, and inverter are sub assembled into a drive unit to optimize mass, cost, and package spacing. The motors are the largest part of the drive unit, and the drive unit orientation in vehicle is adjusted to have the motors as low and towards the center of the vehicle as possible, reducing the center of gravity and the vehicle's polar moment of inertia.
  • Interior permanent magnet motors and water jacket cooled stator. Motor air space is a sealed "air cavity" that is shared with the Dual Power Inverter Module, DPIM.
  • Fully automatic, 2 stage, single speed reduction gearset for each wheel. Left and right gearsets share oil and a common cavity for a given drive unit. The gearsets share many parts and utilize a 12.6:1 ratio on the front and rear drive units.
  • Inverters: Front drive units are silicon carbide, while rear drive units are silicone based IGBT's. All drive units share a single capacitor for 2 motors which reduces cost, mass, and package space.
  • Drivetrain: Ball spline half-shafts are utilized to maximize half-shaft durability, efficiency, and torque capacity during high articulation suspension events. On the rear drive unit, a modular disconnect is utilized to decouple the half-shaft from the output gears such that the vehicle can operate in FWD. This allows a significant range improvement during low power output and steady state cruise driving events.
  • Battery
    • The Battery pack consists of 7,776 lithium-ion battery cells which are arranged in 9 cell modules. The 9 cell modules are assembled into a fully sealed enclosure built from an aluminum frame structure. The lid includes a removable service access panel, and the bottom plate provides protection from ground strikes consistent with the vehicle’s on and off-road capability. Liquid coolant is distributed in parallel to each cell module via the coolant manifold. A Battery Management System (BMS) communicates battery operation with other vehicle systems, controls the contactors, and monitors current, voltage, and isolation measurements. The BMS also monitors sensors for detection of gases, water, and bottom plate puncture.
    • Battery pack nominal capacity is 360 Ah based on a constant current C/5 discharge rate.
    • The thermal management system for the high voltage battery is a liquid coolant system. A pump circulates coolant thru the battery and a refrigerant-cooled chiller to extract heat and lower the temperature of the battery. In cold weather, an in-line heating element is used to heat the coolant to raise the temperature of the battery.
    • Battery management control system is programmed to prevent a state of under-voltage or over-voltage per the voltage limits defined by Rivian. Contactor opens and DTCs are set when voltage of the 9 module 135 kWh battery is below 216 V or above 459 V.
  • Regenerative Braking System
    • The regenerative braking system can use up to all 4 electric propulsion motors to convert the vehicles kinetic energy to electrical energy which is stored in the vehicles high voltage battery.
    • The regenerative control logic uses two main inputs, acceleration pedal position and vehicle speed to determine a desired regenerative braking torque. The requested braking torque is then distributed between the front and rear axles based on the vehicle state, axle disconnect status, and calculated normal force on each axle. The regenerative torque is limited when the vehicle experiences low wheel traction events (e.g. ice or snow).
    • The percentage of braking performed on road by each axle is constantly changing and redistributing. It is based on the driver demanded torque and has been optimized for vehicle dynamics and range attributes.
  • Overlap of friction brakes and regenerative braking
    One pedal driving is the default, in this mode, fully releasing the pedal yields the maximum regen level. And about halfway through the pedal travel is the neutral point, where regen is limited. As the driver manually increases primary service brake pressure and friction braking torque, the vehicle regen level will proportionally ramp down to 0 Nm based on the driver braking pressure. The ramp profile is affected by many factors. When autohold is active and the vehicle approaches standstill, the braking torque will blend from motors to friction brakes.
  • Charging:
    • AC Level 1 Charging at 120 V / 12 A
    • AC Level 2 Charging at 240 V / 48 A
    • DC Fast Charging at up to 210 kW
  • Range:
    • Tested in both Conserve and Sport modes, then averaged
    • Difference of ~12% (Slightly less impact on the hwy vs city) between the modes - Conserve Mode should get you +6% range, Sport -6%
    • Cold Weather (20 degrees F) phase (performed on the City cycle only):
      Conserve mode = -27%
      Sport Mode = -57%
      Average cold weather (city) impact -41%
A few questions answered - more questions raised

EDIT: For those looking for the documents
https://iaspub.epa.gov/otaqpub/publist1.jsp
Select "Applications" for document type and "Rivian" for manufacturer (the others are not required), then search.
The older docs have a few more details about the trucks, the newest has all the test results.

The range/test figures above are only for the R1T. I haven't looked closely at the R1S results yet but would expect them to be similar
Of all the Rivian content I've seen today, this is the best part. THanks for posting technical details!

Do we know if they have a heat pump or resistive cabin heater? That also makes a big difference in cold weather.
 

SeaGeo

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@DucRider did you happen to see max regen? I saw one of the reviews mentioned 150 kW, which seems pretty low for the power of the truck and size of the battery.

Also, any thoughts on the 210kw max? Any insight into if that limit would still apply with the 800v switch?
 

DB-EV

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27% is the COLD WEATHER penalty when in Conserve mode.

The overall rating looks to be about 6% better in conserve

Conserve Range: 334 miles
Sport Range: 293
Good job DucRider - my mystery solved: If Conserve gets you to 334, and you get a 10% hit, this explains the 302, 308 numbers we have seen on the 20 ATs in videos.

I am really interested in the cold weather penalty. I skimmed the report but clearly did not decipher it as well as you.
 

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In one of the videos today, it was mentioned 0.3... not sure of this is official though
Yeah I caught that too, said Rivian engineer said 0.3 and that they had done extensive wind tunnel testing. Can't remember which review, I watched too many lol. Still word of mouth though...
 
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Do we know if they have a heat pump or resistive cabin heater? That also makes a big difference in cold weather.
No heat pump

@DucRider did you happen to see max regen? I saw one of the reviews mentioned 150 kW, which seems pretty low for the power of the truck and size of the battery.

Also, any thoughts on the 210kw max? Any insight into if that limit would still apply with the 800v switch?
No mention of actual regen kW

IF they have the wiring/switching in place in the roll out units, then it is a software change and the spec changes and the limit should go up to the ~300kW and be at a lower amperage.
The switch could be implemented on each of the 9 modules, but it might be more efficient to have a single switch. Both would have the effect of "rewiring" the pack from 108s 72p (nominal 400V & 360Ah) to 216s 36p (nominal 800V & 180Ah) while charging
 

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Guessing the hard likely reality of cold weather range. I don't think this is new for EVs but seeing the numbers makes it more real. I would be using my R1S for long distance snowboarding trips; this is a reminder that especially in cold and if snow, range remains king. Will the larger pack R1S add that much more when accounting for a possible 40 percent range hit? Lots to think about...
 

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Guessing the hard likely reality of cold weather range. I don't think this is new for EVs but seeing the numbers makes it more real. I would be using my R1S for long distance snowboarding trips; this is a reminder that especially in cold and if snow, range remains king. Will the larger pack R1S add that much more when accounting for a possible 40 percent range hit? Lots to think about...
That's my guess too. Just curious. I also think this is one area where we the EPA testing is conservative.

Boarding is definitely one of my main plans too. Once you get going and the pack is warm, I doubt it will be nearly that bad. It's funny, people have noticed that the ID.4 takes a decent efficiency hit for short trips because it *always* tries to keep the battery at a target temp. So for short trips it consumes a noticeable amount of juice warming it up, even in moderate weather.
 

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Yeah I caught that too, said Rivian engineer said 0.3 and that they had done extensive wind tunnel testing. Can't remember which review, I watched too many lol. Still word of mouth though...
It was the Electrek.co video "walk-around" I think. Sorry don't have the link handy on my phone. I stopped watching part way through as I was frustrated that they kept blocking the camera when talking about interior features. Was one of the worst videos I watched in todays review dump.
 

ajdelange

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@DucRider did you happen to see max regen? I saw one of the reviews mentioned 150 kW, which seems pretty low for the power of the truck and size of the battery.[/QUOTE}Actually it matches the battery size pretty nicely corresponding to 1.11C and that's enough to provide about 0.13 g at 70 mph.

Also, any thoughts on the 210kw max? Any insight into if that limit would still apply with the 800v switch?
OP lists battery pack maximum charging voltage at 450V. For 210 kW the current is 467 A which is close to the 500A limit of a CharIN HPC350 compliant charger. Limiting current to 500A and voltage to 450V implies a maximum rate of 225 kW. But note that even increasing the current from 467 to 500 A (7.1%) increases the heat dissipated in the battery by 14.6% and that even 210 kW is 1.56C. This is higher than usual and I'd guess that Rivian wants to proceed cautiously before going to higher rates.

To intelligently discuss the implications of going to the series pack configuration I'd need to know the cell impedance and I don't.
 
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Just the range hit on the cold weather. I live at under 20F for a good three to four months of the year. I expected a hit, but not 40%. Guess I should have done more research
 
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