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How close do you think real world range will be to EPA range?

The Real World Range will be...


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mkhuffman

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Note: In your numbers, you need to drop the k from kWh/mi to just Wh/mi. 399 kW per mile would be pretty high consumption.
Thanks! I missed that. And realized I fat fingered the formula in the last sentence also. Fixed.
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mkennedy1996

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If we assume the EPA range will be 400 miles (which includes city driving and very slow highway driving), then we get 400/(180*.9) = 2.46 kWh/mi (or 405 Wh/mi).
My prediction is that Rivian is going to follow Tesla's lead and make nearly all of the battery usable with the guidance to only charge above 90% when needed. So, if I am correct, the formula would be 179.3 kw of usable battery / 419 miles of range = 428 Wh/mi.

Just a WAG.
 

mkennedy1996

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Here is an article with the etron and the ipace at 70mph. I agree with the ~500Wh/mi, but the Rivians look boxier, so who knows...

E-tron: 508 Wh/mi
I-Pace: 478Wh/mi
They also had the Polestar 2 and M3p.
P2: 380 Wh/mi
M3P: 350 Wh/mi

https://arstechnica.com/cars/2020/08/teslas-model-3-beats-competitors-in-70mph-range-test/
Thanks for the article. Interesting. I can't seem to find the Wh/mi data in the article. Am I missing something?

So they traveled 75% of their EPA range (Tesla) up to 92% of their EPA range (E-Tron) at 70 mph. [No surprise that again Tesla's range is grossly overstated]. [This especially strange because the Tesla is so much more aerodynamic that you would expect it to do better on the 70 mph test. Tesla is the master of the EPA test fallacy].

Using those ratios (EPA to actual at 70mph) with the projected wh/mile of 428 for the Rivian, we come to a 70 mph Wh/mi of between 465 and 571 Wh/mi. Let's hope that Rivian ratio is closer to the E-Tron than the Tesla at 70 mph.
 

Babbuino

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Thanks for the article. Interesting. I can't seem to find the Wh/mi data in the article. Am I missing something?

So they traveled 75% of their EPA range (Tesla) up to 92% of their EPA range (E-Tron) at 70 mph. [No surprise that again Tesla's range is grossly overstated]. [This especially strange because the Tesla is so much more aerodynamic that you would expect it to do better on the 70 mph test. Tesla is the master of the EPA test fallacy].

Using those ratios (EPA to actual at 70mph) with the projected wh/mile of 428 for the Rivian, we come to a 70 mph Wh/mi of between 465 and 571 Wh/mi. Let's hope that Rivian ratio is closer to the E-Tron than the Tesla at 70 mph.
I just did the math with the advertised battery size. 95 for the etron and 90 for the ipace
 

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mkennedy1996

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Is the 419 miles of range a wag, or did that come from another source?
Sort of an educated WAG.

If their data indicating 428 Wh/mi holds true and my assumption that they will make nearly all of the battery available, then the math works out to a 419 mile range.

Unless their data on charging speeds published on their webpage is very wrong, then they pretty much have to be making the entire battery usable at the sizes they indicated (slightly less than 135kW or 180kW).

The wiggle room begins when we try to determine which R1 the 428Wh/mi corresponds to. The R1S has about 3% more range than the R1T. And which tires were used to arrive at these numbers.

And of course, will they simply publish new charging speed specs at the last minute that change all of these calculations.
 

DucRider

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And of course, will they simply publish new charging speed specs at the last minute that change all of these calculations.
Since those times were based on their estimations of the EPA range, and rounding errors could be significant I think you are reading too much into them. 20 minutes for 140 miles could be rounded from 18 minutes for 142 miles (I've never seen any manufacturer claim down to the mile or the minute)
I would expect them to change at least a little. And they might also be an average for all wheel sizes, or for the worst wheel range.

If you take the 25 miles an hour (also an estimation from their expected EPA rating) from a 48A EVSE and assume a typical 10% charging loss (and no taper), you get 2.42 mi/kWh or 414 Wh/mi.
 

mkennedy1996

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Since those times were based on their estimations of the EPA range, and rounding errors could be significant I think you are reading too much into them. 20 minutes for 140 miles could be rounded from 18 minutes for 142 miles (I've never seen any manufacturer claim down to the mile or the minute)
I would expect them to change at least a little. And they might also be an average for all wheel sizes, or for the worst wheel range.

If you take the 25 miles an hour (also an estimation from their expected EPA rating) from a 48A EVSE and assume a typical 10% charging loss (and no taper), you get 2.42 mi/kWh or 414 Wh/mi.
Here we go again. I have posted this a couple of times before, but I will repost for your benefit. First, all we have is the tea leaves to read into at this point. I did not use the DCFC data as it was not specific to a power level, therefore a calculation could not be made. Rounding was accounted for as you will see below. I would happy to see other data points that you may have to refute the calculations. Please enlighten me.

They publish charging speeds for two different chargers. They do not specify which vehicle these are for, nor do they give specifics on the wheel configuration, which can have an impact on range.

The mobile charger provides 7.68kW of power and adds 16 miles per hour of range.
You have to deduct a percentage of that power that is lost during the charging process in order to come to the power available to add range. In this case I use a charging loss of 8% and 10%.

At a 10% charging inefficiency loss, you have 6,912 watts available to add range. Their spec indicates this would add 16 miles of range (with rounding this could be 15.5 to 16.49):
432Wh/mile - with rounding this could be between (419 to 446Wh/mile)

At an 8% charging inefficiency loss, you have 7,066 watts available to add range. Their spec indicates this would add 16 miles of range (with rounding this could be 15.5 to 16.49):
442Wh/mile - with rounding this could be between (428 to 456Wh/mile)

The hard wired charger provides 11.5kW of power and adds 25 miles per hour of range.

At a 10% charging inefficiency loss, you have 10,350 watts available to add range. Their spec indicates this would add 25 miles of range (with rounding this could be 24.5 to 25.49):
414Wh/mile - with rounding this could be between (406 to 422Wh/mile)

At an 8% charging inefficiency loss, you have 10,580 watts available to add range. Their spec indicates this would add 25 miles of range (with rounding this could be 24.5 to 25.49):
423Wh/mile - with rounding this could be between (415 to 432Wh/mile)

This at those scenarios:
432Wh/mile - with rounding this could be between (419 to 446Wh/mile)
442Wh/mile - with rounding this could be between (428 to 456Wh/mile)
414Wh/mile - with rounding this could be between (406 to 422Wh/mile)
423Wh/mile - with rounding this could be between (415 to 432Wh/mile)
The average of these comes to 428Wh/mile or between (417 to 439Wh/mile)

The overlap in the rounding ranges puts the number closer to 426 Wh/mi.

Based upon available data, that is my best guess
 

azbill

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All of the numbers in terms of Wh/mile or mile/KWh are not that meaningful since it will vary with so many parameters. The title of this thread should be changed to state:

How close do you think your typical trips will be to the EPA driving cycles?
 

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mkhuffman

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All of the numbers in terms of Wh/mile or mile/KWh are not that meaningful since it will vary with so many parameters. The title of this thread should be changed to state:

How close do you think your typical trips will be to the EPA driving cycles?
I respectfully disagree. Wh/mile or mile/kWh are efficiency measures that allow you to compare vehicles and determine how far your vehicle can travel on a charge. I agree there are many variables that impact efficiency, but it is the one measurement that matters when it comes to estimating range. It is really the MPG equivalent in an ICE car.

In answer to your last question: it depends on how Rivian chooses to report their EPA numbers. If they follow the more aggressive reporting method Tesla uses, real world range will be much different than the EPA numbers.

Not to rehash a topic that has been discussed many, many times, but the EPA estimation method includes a lot of driving simulation that most people don't do. For example, they don't do a real world highway test. Most people drive much faster than the EPA tests. So even if Rivian reports conservatively like Ford does (for example), a lot of people will have a hard time meeting the estimate. (That said, new Mach-E owners are getting numbers not that out of line with EPA estimates so it seems Ford taking the right approach with their EPA numbers.)
 
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azbill

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allow you to compare vehicles
My point is the thread is not about comparing vehicles, it is about how much real range will you get in your Rivian. Efficiency measures are only meaningful when combining it with the amount of battery you have, and even that will go down over time (degradation).

I know that the EPA number for my Bolt is 238 miles of range. But I also know, based on real world experience, when I drive at 75mph (Arizona highway speed limit) I get about 190 miles of range, on flat roads with little wind. There is no published EPA or wh/mile specification for that. I also plan my trips to try to charge every 100-130 miles.
 

mkennedy1996

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My point is the thread is not about comparing vehicles, it is about how much real range will you get in your Rivian. Efficiency measures are only meaningful when combining it with the amount of battery you have, and even that will go down over time (degradation).

I know that the EPA number for my Bolt is 238 miles of range. But I also know, based on real world experience, when I drive at 75mph (Arizona highway speed limit) I get about 190 miles of range, on flat roads with little wind. There is no published EPA or wh/mile specification for that. I also plan my trips to try to charge every 100-130 miles.
Since we don't have final figures from Rivian, the comparison to other vehicles is used to guide us to what the Rivian figures will be.

From the base efficiency & range numbers, there are variables that impact range. Understanding what those variables are and how they impact your range is important. The impact each variable has on your range is fairly repeatable. Some people just want to plug in every 100 miles and don't care about the details. That is fine for them, but then why participate in a discussion on the nuances of range, efficiency and real world results? Some people don't own a BEV and benefit from these discussions before getting their Rivian.

In 2018, the Tesla supercharger network was not as expansive as it is today. I planned to tow my 5,000 lb boat from Florida to North Georgia using my Model X. Using the data I had available (I tend to have lots of data), I did the math on Model X efficiency while towing and distance between Superchargers and determined that I could not make the trip with one car. So my wife and I each took our Model Xs and had to swap the Model X towing the boat half way between a number of the Superchargers in order to make the trip. It worked well. Had we not understood the precise impact of the variables and the math involved, we probably would have been stranded along the road or never attempted the trip in a BEV (or 2).
 

mkhuffman

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My point is the thread is not about comparing vehicles, it is about how much real range will you get in your Rivian. Efficiency measures are only meaningful when combining it with the amount of battery you have, and even that will go down over time (degradation).
But the same argument can be made for ICE MPG. The range of an ICE vehicle is dependent on the size of gas tank (and how much fuel is in the tank), but that does not mean the MPG you can achieve in the vehicle is not meaningful. It is important to know your vehicle's MPG in order to know how far you can drive before you need to stop to get gas.
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