Budman
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I've been a R1T owner for about 2.5 years now. First a Gen 1 Quad Motor Large Battery which I recently traded in for a Gen 2 Dual Motor Max Pack. Combined, I have about 60,000 miles on the two vehicles. I'm a bit of a data geek (35 years experience as a Mechancal Design and Test Engineer), I've collect detailed data on my road trip efficiency, range, and charging performance.
What follows is a detailed summary of the data I collected which I offer to you as another reference source to compliment the observations given by some popular YouTube Influencers. I often find those YouTube videos to be superficial despite their length, lacking statistical rigor and proper context, and sometimes just plain wrong.
KEY POINTS TO BE MADE BELOW:
Gen 2 and Gen 1 have similar efficiencies.
Heat pump not yet seen to provide a benefit
Overall range figures meet EPA estimates when driven on a mix of city/rural/highway route.
Gen 2 and Gen 1 have similar fast charging performance.
The most optimal road trip charging strategy is to stop for around 20 to 25 minutes and add around 60 kWh of energy.
It is not necessary to start a charging session at very low states of charge (like 10%) to have a fast road trip. Starting around 20% will yield roughly the same overall time with much less risk.
DETAILED ANALYSIS
Efficiency and Range:
I drive the same 165 mile route frequently. It's a mix of 70mph Freeway and 55mph rural roads with frequent slower sections through intersections and small towns. I think it is close-ish to the EPA combined city/highway test cycle. As such, I have observed my R1Ts have closely matched the EPA stated values for range.
I've posted versions of this next chart many times on this forum. However, this time I have enough data on the Gen 2 Dual Motor Max pack to start making statistically meaningful comparisons. The shaded areas are the 95% confidence intervals on the calculated mean line fit.
Points to Make:
The Gen 2 Dual Motor Max Pack (22" wheels) has very similar efficiency vs temperature performance as the Gen 1 Quad Motor Large Battery (21" wheels) when in Conserve Mode.
I've not yet observed any meaningful efficiency benefit from the heat pump in the Gen 2 vehicle. Sample size is still a bit small, perhaps a benefit will emerge over time.
For the Gen 1 Quad, in warmer temperatures, at the speeds I travel on this route, there is a significant improvement in efficiency in conserve vs all. purpose.
*** This is not a 75 mph highway speed efficiency test. I am not claiming I see this efficiency at higher speeds for extended periods. ****
The calculated full pack range I would see based on these efficiency numbers is shown below;
Points to Make:
Assuming a 131 kWh battery pack for the Gen 1 Quad vehicle. A 141 kWh battery pack for the Gen 2 max pack.
As noted above. My observed range is inline with the EPA test (420 miles for Gen 2 Max Pack).
At around 70 deg F, the range increase in the Gen 2 to Gen 1 is inline with expectations given the 10 kWh larger battery (10 kWh * 3 m/kWh = 30 miles more range)
*** This is not a 75 mph highway speed range test. I am not claiming I see this range at higher speeds for extended periods. ****
Charging Analysis:
I've used Electrify America charges a lot on several long road trips with my Gen 1 Large Pack vehicle. The EA app history provides info on total charging time and energy delivered. I've only done a few charging sessions with the Gen 2 Max pack but I wanted to present these results as it is this topic where I the biggest difference of opinion compared to some of the recent YouTube video on the Gen 2 Max Pack charging behavior.
First chart: The chart below shows the total energy delivered during a charging session on the horizontal axis and the time spend charging on the vertical axis.
Points to Make:
To a first order estimate, the Gen 1 Large pack and Gen 2 Max pack appear to have very similar charging performance when comparing multiple charging sessions of each and taking into account the inevitable variability the occurs when charging an electric vehicle.
As most of us are aware, charging performance follows an exponential function. Adding more and more energy takes longer and longer as the battery gets more fully charged. I used an exponential line fit algorithm to create the solid lines seen on the chart.
One of the data points shown I took from the "10% challenge" video recently posted that was the subject of particular ire from the YouTube influencer.
I don't want to linger too long on this chart because there are some other variables at play that are very important that must be taken into account. These following charts do this.
Charging performance is very dependent on the starting state of charge (denoted SOC on the charts). A low initial SOC will charge faster than a high initial SOC. Fortunately, the EA app history shows the starting and ending SOC for each session. The Tesla app does not do this so I can't do a similar exercise for the supercharger data.
In the next chart I created separate data sets to fit the exponential line to based on the initial states of charge. The data bins are; 10% to 20% initial SOC, 21% to 30% initial SOC, 31% to 40% initial SOC, etc.
Points to Make:
This chart only shows Gen1 Large Pack data (Gen 2 added into the following chart).
You can clearly see the impact of starting a session with a battery that is relatively full (red data, >40% charged. Black data >50% SOC at start of session).
But, charging performance is not overly sensitive to initial SOC if below <30% and the energy added is <70 kWh or so. The green and blue lines are pretty close together and differ by only a couple minutes of charging time. It does not really matter much too much if the battery is say 15% full or 25% full when you start, you get about the same charging performance.
Gen1 Large Pack vs Gen 2 Max Pack Charger Performance
I've done a few charging sessions with the Gen 2 Max Pack. The sessions were at starting states of charge of <20% or between 30% and 40%. For clarity I removed the other data bins. And I added in the data from the "10% challenge" YouTube video.
Points to Make:
Gen 2 Max Pack shown in the large square markers.
When factoring in the initial states of charge of the batteries, the Gen 2 Max Pack has charged very similarly to the Gen 1 Large Pack
Over more charging sessions perhaps a difference will emerge but the difference would likely be on the order of a couple minutes or less.
*** Disclaimer: My Gen 2 Max pack sessions have been in cool to cold weather. I have not evaluated the performance in temperatures >50 Deg F ****
Efficient Road Trip Charging Strategy for Rivian Vehicles
With the exponential curve fits vs SOC in hand I can do some interesting road trip simulations to evaluate different charging strategies. For the example that follows I said a traveler needs to add 300 kWh of energy on the road (about 600 to 700 miles of traveling). I looked at charging times if stopping 4, 5, 6, 7, 8 or 9 times. The required energy to be added at each stop is 300 divided by n (number of stops) which works out to 75, 60, 50, 42.5, 37.5 or 33.3 kWh per stop. For the first chart I assumed 8 minutes of overhead time per stop (getting off the highway, traversing to the charger, fiddling with apps, get back on the freeway).
Chart explanation:
Actual charging time calculated for the exponential curve fits are in the text blocks next to each data point.
The horizontal axis is number of stops and energy to be added.
Vertical axis is total charing + overhead time summed up over the n number of stops
Green line assuming a starting state of charge of <20% and the blue is starting SOC between 21% and 30%
Points to Make:
The optimal solution for Rivian vehicles is a 5 stop strategy onboarding 60 kWh with charging times between 20 and 23 minutes depending on initial battery level.
Faster overall charging time is quicker with very low battery levels but I view this as a high risk, low reward strategy. Adding 15 minutes to my is insignificant compared to the consequences pushing the envelope and running out of battery.
A wide range of solutions are within 15 minutes of the "best" solution. To me, that does not matter. Don't obsess over charging stops/battery levels etc. Charge when the battery is down around 20% or so, charge for 20 to 25 minutes an add around 60 kWh.
Eight minutes of overhead might be on the high side the the 2nd chart shows a 4 minute over head simulation.
4 Minutes of overhead:
Points to Make:
With less overhead a 6 stop strategy might be ever so slightly better than the 5 stop strategy.
Again, many solutions are within 10 minutes of the "best" solution. Don't obsess over it.
Speaking of obsessing... A well known YouTube Influencer seems to be very obsessed with charging speeds and strategies. The 10% challenge test with 15 minutes of charging time is held as an example of a smart road trip strategy. Strictly speaking, 15 minutes of charging time is demonstratively NOT the best solution for the Rivian vehicles. It is not significantly worse that the best and it might be the best for other vehicles but not for Rivian vehicles.
For completeness the chart below included how much time it would take if you initiated every charging session with a pretty full battery. It could add over an hour to your trip time.
Bonus chart:
Supercharger vs Electrify America; I can’t break it out by initial SOC but lumping everything together shows the Superchargers and EA to be, on average, the same for charging times.
What follows is a detailed summary of the data I collected which I offer to you as another reference source to compliment the observations given by some popular YouTube Influencers. I often find those YouTube videos to be superficial despite their length, lacking statistical rigor and proper context, and sometimes just plain wrong.
KEY POINTS TO BE MADE BELOW:
Gen 2 and Gen 1 have similar efficiencies.
Heat pump not yet seen to provide a benefit
Overall range figures meet EPA estimates when driven on a mix of city/rural/highway route.
Gen 2 and Gen 1 have similar fast charging performance.
The most optimal road trip charging strategy is to stop for around 20 to 25 minutes and add around 60 kWh of energy.
It is not necessary to start a charging session at very low states of charge (like 10%) to have a fast road trip. Starting around 20% will yield roughly the same overall time with much less risk.
DETAILED ANALYSIS
Efficiency and Range:
I drive the same 165 mile route frequently. It's a mix of 70mph Freeway and 55mph rural roads with frequent slower sections through intersections and small towns. I think it is close-ish to the EPA combined city/highway test cycle. As such, I have observed my R1Ts have closely matched the EPA stated values for range.
I've posted versions of this next chart many times on this forum. However, this time I have enough data on the Gen 2 Dual Motor Max pack to start making statistically meaningful comparisons. The shaded areas are the 95% confidence intervals on the calculated mean line fit.
Points to Make:
The Gen 2 Dual Motor Max Pack (22" wheels) has very similar efficiency vs temperature performance as the Gen 1 Quad Motor Large Battery (21" wheels) when in Conserve Mode.
I've not yet observed any meaningful efficiency benefit from the heat pump in the Gen 2 vehicle. Sample size is still a bit small, perhaps a benefit will emerge over time.
For the Gen 1 Quad, in warmer temperatures, at the speeds I travel on this route, there is a significant improvement in efficiency in conserve vs all. purpose.
*** This is not a 75 mph highway speed efficiency test. I am not claiming I see this efficiency at higher speeds for extended periods. ****
The calculated full pack range I would see based on these efficiency numbers is shown below;
Points to Make:
Assuming a 131 kWh battery pack for the Gen 1 Quad vehicle. A 141 kWh battery pack for the Gen 2 max pack.
As noted above. My observed range is inline with the EPA test (420 miles for Gen 2 Max Pack).
At around 70 deg F, the range increase in the Gen 2 to Gen 1 is inline with expectations given the 10 kWh larger battery (10 kWh * 3 m/kWh = 30 miles more range)
*** This is not a 75 mph highway speed range test. I am not claiming I see this range at higher speeds for extended periods. ****
Charging Analysis:
I've used Electrify America charges a lot on several long road trips with my Gen 1 Large Pack vehicle. The EA app history provides info on total charging time and energy delivered. I've only done a few charging sessions with the Gen 2 Max pack but I wanted to present these results as it is this topic where I the biggest difference of opinion compared to some of the recent YouTube video on the Gen 2 Max Pack charging behavior.
First chart: The chart below shows the total energy delivered during a charging session on the horizontal axis and the time spend charging on the vertical axis.
Points to Make:
To a first order estimate, the Gen 1 Large pack and Gen 2 Max pack appear to have very similar charging performance when comparing multiple charging sessions of each and taking into account the inevitable variability the occurs when charging an electric vehicle.
As most of us are aware, charging performance follows an exponential function. Adding more and more energy takes longer and longer as the battery gets more fully charged. I used an exponential line fit algorithm to create the solid lines seen on the chart.
One of the data points shown I took from the "10% challenge" video recently posted that was the subject of particular ire from the YouTube influencer.
I don't want to linger too long on this chart because there are some other variables at play that are very important that must be taken into account. These following charts do this.
Charging performance is very dependent on the starting state of charge (denoted SOC on the charts). A low initial SOC will charge faster than a high initial SOC. Fortunately, the EA app history shows the starting and ending SOC for each session. The Tesla app does not do this so I can't do a similar exercise for the supercharger data.
In the next chart I created separate data sets to fit the exponential line to based on the initial states of charge. The data bins are; 10% to 20% initial SOC, 21% to 30% initial SOC, 31% to 40% initial SOC, etc.
Points to Make:
This chart only shows Gen1 Large Pack data (Gen 2 added into the following chart).
You can clearly see the impact of starting a session with a battery that is relatively full (red data, >40% charged. Black data >50% SOC at start of session).
But, charging performance is not overly sensitive to initial SOC if below <30% and the energy added is <70 kWh or so. The green and blue lines are pretty close together and differ by only a couple minutes of charging time. It does not really matter much too much if the battery is say 15% full or 25% full when you start, you get about the same charging performance.
Gen1 Large Pack vs Gen 2 Max Pack Charger Performance
I've done a few charging sessions with the Gen 2 Max Pack. The sessions were at starting states of charge of <20% or between 30% and 40%. For clarity I removed the other data bins. And I added in the data from the "10% challenge" YouTube video.
Points to Make:
Gen 2 Max Pack shown in the large square markers.
When factoring in the initial states of charge of the batteries, the Gen 2 Max Pack has charged very similarly to the Gen 1 Large Pack
Over more charging sessions perhaps a difference will emerge but the difference would likely be on the order of a couple minutes or less.
*** Disclaimer: My Gen 2 Max pack sessions have been in cool to cold weather. I have not evaluated the performance in temperatures >50 Deg F ****
Efficient Road Trip Charging Strategy for Rivian Vehicles
With the exponential curve fits vs SOC in hand I can do some interesting road trip simulations to evaluate different charging strategies. For the example that follows I said a traveler needs to add 300 kWh of energy on the road (about 600 to 700 miles of traveling). I looked at charging times if stopping 4, 5, 6, 7, 8 or 9 times. The required energy to be added at each stop is 300 divided by n (number of stops) which works out to 75, 60, 50, 42.5, 37.5 or 33.3 kWh per stop. For the first chart I assumed 8 minutes of overhead time per stop (getting off the highway, traversing to the charger, fiddling with apps, get back on the freeway).
Chart explanation:
Actual charging time calculated for the exponential curve fits are in the text blocks next to each data point.
The horizontal axis is number of stops and energy to be added.
Vertical axis is total charing + overhead time summed up over the n number of stops
Green line assuming a starting state of charge of <20% and the blue is starting SOC between 21% and 30%
Points to Make:
The optimal solution for Rivian vehicles is a 5 stop strategy onboarding 60 kWh with charging times between 20 and 23 minutes depending on initial battery level.
Faster overall charging time is quicker with very low battery levels but I view this as a high risk, low reward strategy. Adding 15 minutes to my is insignificant compared to the consequences pushing the envelope and running out of battery.
A wide range of solutions are within 15 minutes of the "best" solution. To me, that does not matter. Don't obsess over charging stops/battery levels etc. Charge when the battery is down around 20% or so, charge for 20 to 25 minutes an add around 60 kWh.
Eight minutes of overhead might be on the high side the the 2nd chart shows a 4 minute over head simulation.
4 Minutes of overhead:
Points to Make:
With less overhead a 6 stop strategy might be ever so slightly better than the 5 stop strategy.
Again, many solutions are within 10 minutes of the "best" solution. Don't obsess over it.
Speaking of obsessing... A well known YouTube Influencer seems to be very obsessed with charging speeds and strategies. The 10% challenge test with 15 minutes of charging time is held as an example of a smart road trip strategy. Strictly speaking, 15 minutes of charging time is demonstratively NOT the best solution for the Rivian vehicles. It is not significantly worse that the best and it might be the best for other vehicles but not for Rivian vehicles.
For completeness the chart below included how much time it would take if you initiated every charging session with a pretty full battery. It could add over an hour to your trip time.
Bonus chart:
Supercharger vs Electrify America; I can’t break it out by initial SOC but lumping everything together shows the Superchargers and EA to be, on average, the same for charging times.
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