Rivian technical nuggets gleaned from EPA application docs

[OldGoat]

Question for all you engineers. Earlier in this thread I saw the table showing the efficiency at various temperatures. Even wIthout it being graphed, it was easy to see that it is neither linear nor parabolic. It almost seems random. I would have assumed a much more predictable pattern. Is this due to testing inconsistency where, for example, the 70-75 temp range was performed at 71 degrees, the 65-70 was 68 and the 60-65 was done at 62 degrees?

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[Condor]

I enjoy reading this technical data but I would also appreciate some bottom line info….

If I’m going on the highway to take a road trip (assuming mild temperatures outside), what is the range I can get with each tire option? Does “conserve mode” limit other functions too much to make it not desirable?

I’m trying to decide, I really want the 20” AT wheels but if I’m really going to get 250 miles of range at highway speeds I’ll reluctantly go with the 21’s

 

[ajdelange]

Question for all you engineers. Earlier in this thread I saw the table showing the efficiency at various temperatures. Even wIthout it being graphed, it was easy to see that it is neither linear nor parabolic. It almost seems random. I would have assumed a much more predictable pattern. Is this due to testing inconsistency where, for example, the 70-75 temp range was performed at 71 degrees, the 65-70 was 68 and the 60-65 was done at 62 degrees?

That data was the poster's record from a program called TeslaFi which uses the Tesla API to query the car for data a logs it. Irrelevant to the question being asked but I certainly hope someone will develop a similar program for the Rivians. That aside the data represents what this particular individual logged in his particular driving experience and can only be considered an example of how this model behaves with temperature. The simple explanation is that there simply isn't enough data to expect a smooth histogram to emerge. Not enough to average out the effects of coarse temperature quantization you alluded to earlier. Also driving at 24.7 °F on a dry road bed is very different from driving at that same temperature with snow on the road. He aslo posted a record of a single drive in which he averaged over 800 Wh/mi because he was driving in snow. Anything on the surface pushes the rolling resistance up fast.

 

[OldGoat]

Thanks...I obviously did not understand the context. I wonder what the graph would look like if temperature were the only variable.

 

[skyote]

WTF I want to know is how is a truck more efficient than a shorter and theoretically less weight SUV. Did we ever get that answer?

Combination of two things, and R1S real world will be even better.

1) The 30% adjustment for R1S vs 28% for R1T.
2) The 55/45 split between City & Hwy.

R1S city range is lower because of the larger adjustment factor AND that has a higher weighting in the test. I would expect both vehicles to be similar in City, and R1S to be better on highway; depending on your driving mix, R1S could start to do much better as amount of highway driving increases.

 

[R1S Maineiac]

Combination of two things, and R1S real world will be even better.

1) The 30% adjustment for R1S vs 28% for R1T.
2) The 55/45 split between City & Hwy.

R1S city range is lower because of the larger adjustment factor AND that has a higher weighting in the test. I would expect both vehicles to be similar in City, and R1S to be better on highway; depending on your driving mix, R1S could start to do much better as amount of highway driving increases.

The good part for me is that our southbound adventures are all downhill for the 1st 70 miles after leaving the house, so I'll be able to feather the pedal and save some of that juice for the back end of Leg 1.

 

[Speedrye]

There's something off in the 20-degree cold weather testing numbers.
In Conserve mode, the vehicle made it 357 miles using 125kWh while in Sport mode, the vehicle made it 186 miles using 74kWh.

Why only 74kWh? All of the other tests discharged 125 to 130kWh or so.
It appears that the Sport test was on the R1S while the Conserve test was on the R1T. If that 74kWh is extrapolated out to the same 125kWh-130kWh discharge energy of the other tests and compared with the R1S city sport tests, it also loses the same 27% of range as the R1T in Conserve mode.

Am I missing something?

 

[Autolycus]

There's something off in the 20-degree cold weather testing numbers.
In Conserve mode, the vehicle made it 357 miles using 125kWh while in Sport mode, the vehicle made it 186 miles using 74kWh.

Why only 74kWh? All of the other tests discharged 125 to 130kWh or so.
It appears that the Sport test was on the R1S while the Conserve test was on the R1T. If that 74kWh is extrapolated out to the same 125kWh-130kWh discharge energy of the other tests and compared with the R1S city sport tests, it also loses the same 27% of range as the R1T in Conserve mode.

Am I missing something?

I think there's a typo or error in the notes to that test. I assume this is where you got the 74kWh number?

Drive Mode: Sport Driver Trace Ratings are for the full CD averaged. 73.55 kWh DC discharge energy. Recharge Event Energy is from MCT 146.9 kWh

Here's the note for the other cold test, which showed a Recharge Event Energy of 151.1 kWh:

Drive Mode: Conserve Driver Trace Ratings are for the full CD averaged. 124.93 kWh DC discharge energy. Recharge Event Energy data from MCT.

All of the other tests have data that looks more like that 2nd one I quoted, rather than the 1st. The difference in discharge energy and "recharge event energy" should account for efficiency losses during charging, right? If so, I think the discharge number is just listed wrong on the one cold test.

 

[Speedrye]

I think there's a typo or error in the notes to that test. I assume this is where you got the 74kWh number?



Here's the note for the other cold test, which showed a Recharge Event Energy of 151.1 kWh:



All of the other tests have data that looks more like that 2nd one I quoted, rather than the 1st. The difference in discharge energy and "recharge event energy" should account for efficiency losses during charging, right? If so, I think the discharge number is just listed wrong on the one cold test.

That's the way I'm reading it. The original post in this thread is coming up with 57% loss in cold weather and averaging it out at 41% loss based on that number, but I don't think that's right. Not sure what's going on.

 

[DucRider]

That's the way I'm reading it. The original post in this thread is coming up with 57% loss in cold weather and averaging it out at 41% loss based on that number, but I don't think that's right. Not sure what's going on.

I don't know how the test is going to relate to actual real world, but last night I pulled some data from other 5 cycle test vehicles. VW/Audi don't include the cold weather data in their applications, but Tesla and Lucid do.
I looked at 5 Tesla applications and all were 36% to 37% range loss on the cold weather test vs the UDDS.
Lucid was 49%.

 

[Autolycus]

For the two 20F tests, I'm seeing the raw, unadjusted data as:

Conserve	357.28 miles	151.1 kWh recharge	calc: 422.9 Wh/mile
Sport	186.17 miles	146.9 kWh recharge	calc: 785.3 Wh/mile

Those both appear to have been on the Multi-cycle Test (MCT), which should include both city and highway cycles.

For comparison, here are the standard UDDS/MCT results:

Conserve	490.98 miles	153.28 kWh recharge	calc: 312 Wh/mile
Sport	429.42 miles	146.87 kWh recharge	calc: 342 Wh/mile

So yes, that's 27.2% and 56.6% drops in miles on a pretty equivalent recharge energy in each mode.

 

[Speedrye]

For the two 20F tests, I'm seeing the raw, unadjusted data as:

Conserve	357.28 miles	151.1 kWh recharge	calc: 422.9 Wh/mile
Sport	186.17 miles	146.9 kWh recharge	calc: 785.3 Wh/mile

Those both appear to have been on the Multi-cycle Test (MCT), which should include both city and highway cycles.

For comparison, here are the standard UDDS/MCT results:

Conserve	490.98 miles	153.28 kWh recharge	calc: 312 Wh/mile
Sport	429.42 miles	146.87 kWh recharge	calc: 342 Wh/mile

So yes, that's 27.2% and 56.6% drops in miles on a pretty equivalent recharge energy in each mode.

Where's the discharge discrepancy coming from?
On Conserve, there was the 151.1kWh recharge with 124.93kWh discharge, but in Sport, there was 146.9kWh recharge with only 73.55kWh of discharge. At the same temperature, I'd expect the discharge rate to be similar, as it was in every other test.

 

[Trandall]

Question for some of the more smarty pants or that have experience owning an EV; Is my consumption correct that their is some overlap in the realized range loss between setting the charge mode to daily (70% max charge) and the cold weather Range hit? My question stated differently would my LE R1T on AT wheel/ tires set to daily charge on a 20 F day with snow covered road driven under conditions similar to the 5 cycle look like this 314*.875(wheel derating)*.7(daily charge setting)*.6(temperature derating)*.7(snowy road derating)=80.77 miles ?
I also think it's worth mentioning that very few of us will be cold soaking our R1's when not in use, I'm assuming keeping it plugged in would allow the BMS to use "shore" power to warm the battery so it never experiences ambient conditions and the temperature derating is much less.

PS. smarty pants was intended respectfully, I really enjoy learning from many of the members here and admire your analytical brains.

 

[Autolycus]

Where's the discharge discrepancy coming from?
On Conserve, there was the 151.1kWh recharge with 124.93kWh discharge, but in Sport, there was 146.9kWh recharge with only 73.55kWh of discharge. At the same temperature, I'd expect the discharge rate to be similar, as it was in every other test.

Like I said earlier, I suspect the discharge is a typo or mistake.

 

[Speedrye]

The limited discharge aligns with the really low mileage though, so I'm wondering if the recharge isn't the typo.

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