R1S Range and Energy consumption

[mkennedy1996]

It will be interesting to see the Drag Coefficient and Energy consumption for the R1S when the official figures are released. In the meantime, it is interesting to speculate using the available data and comparable vehicles.

This photo shows the Drag Coefficients for various vehicles, including the Range Rover which is similar in design, as well as the other large (ish) BEVs. The R1S is taller and wider than all the BEVs. It is similar to the Range Rover (shorter but wider), which has a Drag Coefficient of 0.39. This is much higher than the Model X, which is 0.24.

Frontal area is another important factor in determining the impact upon range, but I was not able to locate these figures for most of the vehicles. The picture will guide you in comparing among the vehicles on the differences in frontal area.

The efficiency of the powertrain is another element. Tesla made significant improvements in the Model X efficiency over the years, primarily with the move to permanent magnet motors. Does Rivian use permanent magnet motors?

Rivian can improve upon the Range Rover drag coefficient with the a smooth underbody and other design choices, but an improvement beyond the 0.3 to 0.35 range will be difficult due to the overall size and shape of the vehicle.

When you factor in the following:

- Relatively high drag coefficient compared to other BEVs (projected)
- Large frontal area compared to other BEVs
- Large tire sizes of 21” for road tires, 22” for performance tires and 20” for all terrain
- High performance motors delivering quick acceleration (range is reduced in high performance motors over regular motors in a Tesla for example)

You might conclude that rated average energy consumption will be above 400 wH/mi, probably around 425 wH/mi using the 21” rims. (wH/mi is the amount of energy required to move the vehicle 1 mile. The attached photo shows the energy needed to move some other BEVs). Using 132 kW as a battery pack size (they have said it is no longer 135, but somewhat smaller), you come to a range of 310 miles for the R1S Large Pack with 21” Rims.

Tesla vehicles see a ~10% range reduction by going from 20” to 22” wheels. The change on an R1S from 21” to 22” is less severe and may equate to about a 5% range reduction. This would give the R1S Large Pack with 22” Rims a range of 295 miles at 446 wH/mi (a 15 mile range penalty for the larger rim size).

What do others think about the wH/mi ratings for the R1S with 21” and 22” rims.

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[ajdelange]

I'm missing something. If the consumption for the Tesla is 368 Wh/mi then the consumption for 100 miles is 36800 = 36.8 kWh yet the table says 43 kWh. ??

Plus the consumption for the X isn't anything like 368 Wh/mi. It's rated consumption is 272 Wh/mi. I realize about 280 in normal driving and a little over 300 at high speed on the freeway.

That aside my gut says the R1T will use something like 420 Wh/mi with the factory's most efficient wheel/tire. But that is no more than gut as I have no idea what actual Cd nor effective frontal area may be.

 

[mkennedy1996]

I'm missing something. If the consumption for the Tesla is 368 Wh/mi then the consumption for 100 miles is 36800 = 36.8 kWh yet the table says 43 kWh. ??

Plus the consumption for the X isn't anything like 368 Wh/mi. It's rated consumption is 272 Wh/mi. I realize about 280 in normal driving and a little over 300 at high speed on the freeway.

That aside my gut says the R1T will use something like 420 Wh/mi with the factory's most efficient wheel/tire. But that is no more than gut as I have no idea what actual Cd nor effective frontal area may be.

For consistency, the source of information for energy consumption is the EPA. 2020 Tesla Model X Performance (22in Wheels) (fueleconomy.gov)

They provide 2 different energy consumption numbers that I am still researching. The first is shown as 43 kW/100 mi. The second is calculated dividing the size of the battery by the range as shown on the label. The EPA data is not transparent, but I believe it to be comparable being vehicles and that was the intent.

I have been a Model X owner for just under 5 years. We received the 3rd Signature X in Dec 2015. I currently own 2 Model Xs, so I am very familiar with the energy consumption. One of the Xs is a P100DL and the other is 100D. The energy consumption used is very different between the two over their lifetimes. The Model X used in the graphic is a P100D with 22" wheels as this appears closest to the performance level and wheel size of the R1S.

 

[mkennedy1996]

I'm missing something. If the consumption for the Tesla is 368 Wh/mi then the consumption for 100 miles is 36800 = 36.8 kWh yet the table says 43 kWh. ??

Plus the consumption for the X isn't anything like 368 Wh/mi. It's rated consumption is 272 Wh/mi. I realize about 280 in normal driving and a little over 300 at high speed on the freeway.

That aside my gut says the R1T will use something like 420 Wh/mi with the factory's most efficient wheel/tire. But that is no more than gut as I have no idea what actual Cd nor effective frontal area may be.

This article helps somewhat in explaining the EPA testing for EVs.

Edmunds: Why electric vehicle ranges vary from EPA estimate (apnews.com)

 

[DucRider]

They provide 2 different energy consumption numbers that I am still researching. The first is shown as 43 kW/100 mi. The second is calculated dividing the size of the battery by the range as shown on the label.

43 kW/100 mile is measured "from the plug", includes charging losses, and thus will corelate directly with MPGe.
The battery size/range metric is difficult as most often only the rated or potential battery size is available (and sometimes not even that). Some companies like BMW also let you know the "usable" portion. Tesla publishes nothing about battery size for any of their vehicles, but the latest Model X testing docs show needing ~118 kWh from the plug to recharge from empty. This is up from ~114 kWh and is a good indication that Tesla is increasing the energy in their packs or making more of the pack "usable" by reducing upper/lower buffers in order to help get the improved EPA range ratings.

https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=51236&flag=1

When in use in EVs, batteries (as a rule) will not be "fully charged by the BMS (at cell level, 42.V would be fully charged and the usual upper limit is ~ 4.1V). Nor does the car allow the batteries to be fully depleted (to the rated cutoff voltage - often 2.5V but ranges up to 3.0V)

 

[ajdelange]

What I am saying is the the EPA rated consumption of a modern X is 272 Wh/mi and it is based on this that I estimate that a modern R1T will have a rated consumption of about 420 Wh/mi. And experience tells me that I will get from 280 - 310 in the X under actual driving conditions. In plannng a trip why would I want to use a number that does not represent the actual performance of the car? Based on this I'm expecting to see 430 - 460 from the R1T on the road.

As these are the numbers one uses to determine how far one can be expected to be able to drive on a charge of a given size I think those are the numbers readers will be interested in.

The performance Teslas use a larger motor than the normal ones in order to get additional performance and in doing so sacrifices efficiency and range. Why would you choose that Tesla to compare to a Rivian which does not do this?

So I'm thinking a more apples to apples comparison with the X will put the Rivian at 420 i.e. 2/3 as efficient as the X. But note that ABRP estimates the R1T's consumption at 516 Wh/mi. I just can't buy that because it says that the 300 mi version would have a battery with available discharge energy of 153.6 kWh and the 400 mile version 204.8 kWh. Those numbers are quite a bit higher than Rivian was throwing out before they removed references to battery size. By comparison 420 Wh/mi puts the battery discharge energies at, respectively, 126 kWh and 168 kWh. This is more consistent with the sizes of 135 and 180 kWh they used to speak of (we have no idea as to whether 135 referred to gross or net though 135 gross fits nicely with 126 net) but may be a bit optimistic.

 

[DucRider]

Why would you choose that Tesla to compare to a Rivian which does not do this?

I don't know if this was for me or @mkennedy1996 , but I was just using the Tesla X numbers to illustrate the from the plug charging and why dividing range by battery size will yield a different result than the EPA consumption number.

I agree with your assessment of the Rivian Wh/mi numbers (but keep in mind that virtually all other manufacturers express this metric as miles/kWh)

 

[mkennedy1996]

What I am saying is the the EPA rated consumption of a modern X is 272 Wh/mi and it is based on this that I estimate that a modern R1T will have a rated consumption of about 420 Wh/mi. And experience tells me that I will get from 280 - 310 in the X under actual driving conditions. In plannng a trip why would I want to use a number that does not represent the actual performance of the car? Based on this I'm expecting to see 430 - 460 from the R1T on the road.

I used numbers that were available for all of the vehicles to have comparable numbers. As you just stated, the actual numbers are not the same as any of the published numbers, so one has to look for a common starting point and extrapolate from there.

As these are the numbers one uses to determine how far one can be expected to be able to drive on a charge of a given size I think those are the numbers readers will be interested in.

I agree, but actual energy usage data is not available for all of these vehicles and depends upon the type of usage, so there is significant variation. For example, I have a Performance X and Non-Performance. My lifetime average on the Performance is 452 Wh/mi over 30.479 miles and "only" 371 Wh/mi over 20,258 miles with the Non-Performance.

The performance Teslas use a larger motor than the normal ones in order to get additional performance and in doing so sacrifices efficiency and range. Why would you choose that Tesla to compare to a Rivian which does not do this?

I think you are confused. I did use the Performance X with 22" wheels in the comparison, since I estimate this to be closest X to the R1S with 21" or 22" wheels. You, on the other hand, use your car as a comparison, yet your car appears to be a Non-Performance with 20" wheels, which would NOT be a good comparison to the R1S.

So I'm thinking a more apples to apples comparison with the X will put the Rivian at 420 i.e. 2/3 as efficient as the X. But note that ABRP estimates the R1T's consumption at 516 Wh/mi. I just can't buy that because it says that the 300 mi version would have a battery with available discharge energy of 153.6 kWh and the 400 mile version 204.8 kWh. Those numbers are quite a bit higher than Rivian was throwing out before they removed references to battery size. By comparison 420 Wh/mi puts the battery discharge energies at, respectively, 126 kWh and 168 kWh. This is more consistent with the sizes of 135 and 180 kWh they used to speak of (we have no idea as to whether 135 referred to gross or net though 135 gross fits nicely with 126 net) but may be a bit optimistic.

In the end we are close in our projections, I put the R1S with 21" wheels at 425 Wh/mi and 446 Wh/mi with 22" wheels. These would be the rated energy usage under ideal conditions with my mother driving. Real world energy consumption will be more for most everyone.

 

[mkennedy1996]

43 kW/100 mile is measured "from the plug", includes charging losses, and thus will corelate directly with MPGe.
The battery size/range metric is difficult as most often only the rated or potential battery size is available (and sometimes not even that). Some companies like BMW also let you know the "usable" portion. Tesla publishes nothing about battery size for any of their vehicles, but the latest Model X testing docs show needing ~118 kWh from the plug to recharge from empty. This is up from ~114 kWh and is a good indication that Tesla is increasing the energy in their packs or making more of the pack "usable" by reducing upper/lower buffers in order to help get the improved EPA range ratings.

https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=51236&flag=1

When in use in EVs, batteries (as a rule) will not be "fully charged by the BMS (at cell level, 42.V would be fully charged and the usual upper limit is ~ 4.1V). Nor does the car allow the batteries to be fully depleted (to the rated cutoff voltage - often 2.5V but ranges up to 3.0V)

Thank you for this data and link. Interesting and helpful.

I read the document and looked up the UDDS test procedure. Am I reading it correctly, that the 118 kWh shown in the data is not the size of the battery, but rather how much energy was used to recharge the battery, including charger energy loss and energy used by the car during charging to maintain pack temperature etc?

Could the variation you mention from 114kWh to 118kWh be a change in charger efficiency or increased energy for pack temperature maintenance?

 

[DucRider]

I read the document and looked up the UDDS test procedure. Am I reading it correctly, that the 118 kWh shown in the data is not the size of the battery, but rather how much energy was used to recharge the battery, including charger energy loss and energy used by the car during charging to maintain pack temperature etc?

Could the variation you mention from 114kWh to 118kWh be a change in charger efficiency or increased energy for pack temperature maintenance?

It is indeed the amount of energy used to recharge a battery that is run to zero on the dyno (numbers are provided for after both the UDDS and hwy tests - on some vehicles there is a slight difference).

This is done under lab conditions with temperatures and other conditions being equal (or as close as a lab can achieve)

There is some unknown +/- error percentage, but as range has increased for the X, charging kWh has increased over the 2019 and 2020 applications:
https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=46587&flag=1
https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=48715&flag=1
A couple of extra kWh is not enough to account for the amount of range increase, and may be due to other factors, but the same pattern exists on other Tesla models with range increases.

The 2021 Model S also shows 118 kWh
https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=51337&flag=1
While the 2020s show 113 to 114 kWh
https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=48713&flag=1
and the 2019s 111 to 113 kWh
https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=46586&flag=1

Something about getting more range out of the vehicles results in a touch more energy being used to recharge.

 

[neockder]

One thing I dont understand... Your wheel size comparison. The overall circumference of the tire among wheel sizes should be comparable, so why should that effect range? You should be looking at tire sizes if you're comparing to other makes to determine the influence of the overall rotational factor. Understandably there are weight differences between rubber and aluminum so an unsprung weight difference factor is in effect but minimal.

I do like the coefficient of friction discussion, but at what cost? If you're going for a wedge shaped vehicle to begin with, what's the fun in that..

I would like to see a 'hot swap' cargo battery option if they're only going to roll with the 300+ launch model. Whatever it may be, but something that can be added later, IE a daisy chain port to build onto the existing pack; a horizontally oriented unit in the cargo area would not be a deal breaker; offer an air mattress that fills the space aft if youre trying to achieve a flat surface throughout for 'stargazer mode'..

It will be interesting to see the Drag Coefficient and Energy consumption for the R1S when the official figures are released. In the meantime, it is interesting to speculate using the available data and comparable vehicles.

This photo shows the Drag Coefficients for various vehicles, including the Range Rover which is similar in design, as well as the other large (ish) BEVs. The R1S is taller and wider than all the BEVs. It is similar to the Range Rover (shorter but wider), which has a Drag Coefficient of 0.39. This is much higher than the Model X, which is 0.24.

Frontal area is another important factor in determining the impact upon range, but I was not able to locate these figures for most of the vehicles. The picture will guide you in comparing among the vehicles on the differences in frontal area.

The efficiency of the powertrain is another element. Tesla made significant improvements in the Model X efficiency over the years, primarily with the move to permanent magnet motors. Does Rivian use permanent magnet motors?

Rivian can improve upon the Range Rover drag coefficient with the a smooth underbody and other design choices, but an improvement beyond the 0.3 to 0.35 range will be difficult due to the overall size and shape of the vehicle.

When you factor in the following:

- Relatively high drag coefficient compared to other BEVs (projected)
- Large frontal area compared to other BEVs
- Large tire sizes of 21” for road tires, 22” for performance tires and 20” for all terrain
- High performance motors delivering quick acceleration (range is reduced in high performance motors over regular motors in a Tesla for example)

You might conclude that rated average energy consumption will be above 400 wH/mi, probably around 425 wH/mi using the 21” rims. (wH/mi is the amount of energy required to move the vehicle 1 mile. The attached photo shows the energy needed to move some other BEVs). Using 132 kW as a battery pack size (they have said it is no longer 135, but somewhat smaller), you come to a range of 310 miles for the R1S Large Pack with 21” Rims.

Tesla vehicles see a ~10% range reduction by going from 20” to 22” wheels. The change on an R1S from 21” to 22” is less severe and may equate to about a 5% range reduction. This would give the R1S Large Pack with 22” Rims a range of 295 miles at 446 wH/mi (a 15 mile range penalty for the larger rim size).

What do others think about the wH/mi ratings for the R1S with 21” and 22” rims.

 

[ajdelange]

Wheels contribute an inertial load and a drag load. The inertial load is a rotational one but it is still largely recoverable via regen. This load depends on the moment of inertia of the wheel and that depends on the way the weight of it is radially distributed thus a larger diameter wheel is going to have higher moment than a smaller one because there is weight at greater distance from the center. Note that the inertia of the wheel assembly includes the weight of the tire so that it is difficult to say how the inertial loads of the wheels will differ. Wheels also contribute slip loss, part of the rolling resistance loss and drag loss. The magnitudes of these depend on the properties of the materials used to construct the tires and are greater than any non recovered inertial loss.

What I am getting at is that it is tough enough to guesstimate what the Wh/mi are going to be for the baseline Rivians let alone ones with different wheels. The estimates I gave earlier are really based more on gut feel about the size and weight of the vehicle, the numbers Rivian used to publish for battery energy content (though, as mentioned, we don't know if those were gross or net) and comparison with vehicles I do know something about. They also include the assumption that when Rivian promises 300+ mile range they are doing that with the tire that comes with the standard issue car. They give the buyer credit for understanding, I assume, that if they want a special wheel they are going to have to give up something for it (range and $) as it has been noted Tesla owners do.

Unanswered question from OP as to whether the Rivians use PM motors: Yes, I believe they do.

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