Do I really need the Max Pack?

R1THHI

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I prefer to use mi/kWh because it is easier to translate that into distance, and range is my most important reason for paying for the Max pack. In any case, 516 Wh/mi is 1.94 mi/kWh, and I agree that might be possible at 65 mph. Maybe. If the weather is great and there is no excessive load like a resistance heater. It will be harder to achieve that efficiency at 75 mph, of course.

So if the usable capacity of the 180 pack is 162 kWh, that is a highway range of 314 miles, assuming you drive to empty. Most people will aim to recharge no lower than 10%, and a DCFC will probably hit the cliff at 80%, so really on a road trip you are using 70% of 162 kWh, which means a range of 220 miles between chargers.

EVs have a long way to go before they can replace ICE for road trips. Not that I won't do it, but most people will find that sort of range frustrating. The Max pack definitely helps, and if you can afford it, I would definitely get the max pack.

I have not ordered yet, because I want to see real world testing first and I am holding out for the removable roof. But if I do order, it will be the biggest battery they offer.
Appreciate we are getting to data and facts. Would like to see more analysis with real transparent numbers so we all can evaluate the math.

If the prior data analysis is true, seems you will get say 50% of the rating, to be safe and stop for a charge. So the 400 mile pack, will yield you useful 200+-miles avg. and the 300 mile pack 150+-miles avg.

Is that what the analysis and data is pointing to from our forum SMEs?





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Well shoot, I didn’t mean to hurt poor old Commodore’s feelings. Looks like facts on bankrupt GM & their debt problems caused him to blocked me.
 

ajdelange

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I prefer to use mi/kWh because it is easier to translate that into distance, and range is my most important reason for paying for the Max pack.
When you get to driving a BEV you will probably come to prefer Wh/mi as most of us do as it makes assessing your situation on a trip easier on the road. I have 74 miles to go. I multiply that by 516 (actually you'd multiply by 0.5) and come up with 37 kWh required. You have a 180 kWh battery which is 1.8 kWh per percent so the 37 kWh is about 20%, If you have more than 20% in the battery you know you are OK. For this reason most of the displays (in Teslas at least) and most of the programs that track performance and are used for trip planning use Wh/mi. You will probably want to switch but if not keep with what you are comfortable with,

In any case, 516 Wh/mi is 1.94 mi/kWh, and I agree that might be possible at 65 mph. Maybe. If the weather is great and there is no excessive load like a resistance heater. It will be harder to achieve that efficiency at 75 mph, of course.
The only way you will get that at 75 mph is with a 10 mph tailwind or when the destination elevation is appreciably lower than the origin.

So if the usable capacity of the 180 pack is 162 kWh, that is a highway range of 314 miles, assuming you drive to empty.
180 is the usable range and leads to the estimated rated consumption of 450 Wh/mi. Many of us think of the "working range" of the vehicle as 80% of the rated range or 320 mi in the case of the Max R1T. This implies limiting charging to 10% to 90% but in fact most like to stay below 80% if possible. In the Tesla network it generally is but this may not hold in the CCS network at first.


Most people will aim to recharge no lower than 10%, and a DCFC will probably hit the cliff at 80%, so really on a road trip you are using 70% of 162 kWh, which means a range of 220 miles between chargers.
Within the Tesla network most are able to determine range from biological rather than battery needs. They will drive 2 - 3 hrs. Were you to drive at 70 that means 210 mile legs. At 80, 240. Assuming that you only wish to use 80% of the battery that means rated working range of 320 miles. Assuming that your efficiency will be reduced by 20% from highway speed that still leaves 256 mile range. In any case you arrive at the charger and "add" however many miles you need. The software, if you have the trip laid into the computer, will probably tell you how much that is but you can generally figure charging time based on the percent you need to add to the battery. The Telsas seem to charge, on average, at 1C so if you need to add 75% count on about 45 minutes. The Rivian may not charge at 1C (I think the Hyundi charges at about 2C) but we will quickly learn how fast the Rivians are and come up with the appropriate ROT for them.


EVs have a long way to go before they can replace ICE for road trips.
I would disagree with that based on my experience with the Tesla MXLR+ with rated range of 351. Of course we have to recognize that I drive the east coast where SC are plentiful. In general we can just get in the car and go figuring out where we'll charge on the road. Up in Quebec where they are not and all that is available is 50 kW CHAdeMO I have to be more circumspect. There is probably going to be some of the latter with the Rivians. It isn't that CCS stations are that rare. It is largely that many of them are low power.


Not that I won't do it, but most people will find that sort of range frustrating.
I'm a retired guy who takes leisurely road trips from time to time. I find the 3 - 4 hour legs perfectly acceptable. I understand that this might not be the case for the road warrior or for anyone in places where chargers are farther apart than that.

I am fairly certain that you will find your range concerns to be groundless. I often suggest that people in you position go rent a Tesla for a weekend and take a road trip. This should help allay your fears.

The Max pack definitely helps, and if you can afford it, I would definitely get the max pack.
I look at it as insurance. If it starts to rain your consumption will go up by as much as 25% or more. If you encounter headwinds or if the grade is overall uphill your 500 Wh/mi will be 600 or more. The extra on board can cover a large part of this. As you have seen in this thread there are lots of ways to convince yourself that you don't need the bigger battery but in reality you can never have too much. Get the biggest battery you are comfortable paying for.


I have not ordered yet, because I want to see real world testing first and I am holding out for the removable roof.
Anyone who orders a vehicle in the first year of its production is nuts, That, of course, includes most of the people in this forum (including me were there any doubt). For us the novelty overpowers common sense.
 

mkhuffman

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180 is the usable range and leads to the estimated rated consumption of 450 Wh/mi. Many of us think of the "working range" of the vehicle as 80% of the rated range or 320 mi in the case of the Max R1T. This implies limiting charging to 10% to 90% but in fact most like to stay below 80% if possible. In the Tesla network it generally is but this may not hold in the CCS network at first.
Thank you for sharing your experience, since I have not owned a BEV yet. My mind set is already prepared to change, and I know I will have to plan trip stops instead of just heading out. It is much easier to treat a Tesla like a ICE car, when Tesla has done a great job placing SC stations around the US. For non-Telslas, the charging network still has big gaps and problems, like chargers not working. This is what Rivian owners will have to deal with, at least until the charging network gets better. It is getting better every day, so hopefully the gap with Tesla will close soon.

I don't think Rivian will allow us to use the full capacity of the 180 kWh battery pack. Tesla typically does allow most (maybe all) of the capacity to be used, but Ford and other manufacturers do not. The reason is clear: they are trying to protect the battery from damage. The Mustang Mach-E has a 98 kWh battery, but only 88 kWh is available for moving the car down the road. So all calculations need to be done with the usable capacity, not the battery pack size.

Unless I missed it, I don't think Rivian has announced if they plan to make the entire capacity available or not. My assumption is they will not, and 90% of the total battery capacity is a reasonable estimate.
 

mkhuffman

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Appreciate we are getting to data and facts. Would like to see more analysis with real transparent numbers so we all can evaluate the math.

If the prior data analysis is true, seems you will get say 50% of the rating, to be safe and stop for a charge. So the 400 mile pack, will yield you useful 200+-miles avg. and the 300 mile pack 150+-miles avg.

Is that what the analysis and data is pointing to from our forum SMEs?
There are many, many variables that impact driving range in a BEV. Generally range calculations are done assuming good weather and no major battery drain other than moving the car down the road. Heating the cabin is a massive battery drain, especially if resistance heat is used. Cold weather also effects battery performance, reducing range. Rain also decreases driving efficiency, reducing range. To include every variable would be hard, so range is calculated assuming no rain, 70 degrees, and no cabin heat. You just know your range will go down if the weather is bad.

Here is the math:

180 kWh battery pack x 0.9 = 162 kWh usable battery capacity. (Rivian might allow us to use more capacity than 90% of the full pack, but we have to assume they will not and will follow what Ford and others are doing to protect the battery from damage.)

162 kWh x 2.5 mi/kWh = 405 miles of range. (This is EPA, not highway. For comparison the Audi E-tron has a EPA rating of 2.27 mi/kWh, so we are assuming the Rivian will be more efficient than the E-tron. Is that reasonable? Maybe. Rivian has not confirmed anything, so we are only guessing.)

High speed DC charging slows down significantly when your battery reaches 80% charge. Some vehicles slow down more than others. I have heard Audi and Porche don't slow down as much as Ford. We don't know what the Rivian will do, but we know it will slow down. When you are on the road, you will likely rarely charge past 80% because it will take too long. If you use a route planning tool like A Better Route Planner (ABRP), it will send you to a charger when you reach 10% battery life. Generally for range anxiety you will recharge at 10% or higher. So that makes the math for long road trips:

162 kWh x 0.7 = 113.4 kWh of battery available for use between DC fast chargers (70% = 80% - 10%). Then:

113.4 kWh x 2.5 mi/kWh = 283 miles (EPA range, not highway range).

Beyond the above calculations, which are speculative because Rivian has not confirmed anything, the speculation gets even more difficult. However, based on every single EV that has been built and tested, we KNOW highway range will be lower than EPA range unless the manufacturer has purposely lowered their EPA rating using more conservative testing. Porche did that with the Tycan, because real world testing has people beating EPA range estimates easily. I doubt Rivian has done that though. They probably are providing realistic estimates, like Ford did with the Mustang Mach-E.

We also know that aerodynamic resistance has a huge impact on range when you drive faster than 30 mph or so. The faster you drive, the worse the impact. Tesla and others have designed their cars to be very aerodynamic, and although I know Rivian has considered aerodynamics, you can look at the R1T and know it is essentially a big brick that will require a lot of energy to push it through the air at 75 mph. So how much will range be impacted? I don't know, but I would expect a pretty big hit. If you get 1.8 mi/kWh at 75 mph I think that will be great. Probably best case that is what you will see. So the math:

162 kWh x 1.8 mi/kWh = 291.6 miles of highway range (assuming you start at 100% and drive to 0%).
113.4 kWh x 1.8 mi/kWh = 204.12 miles of highway range between DC fast chargers (assuming you start at 80% and charge at 10%).

If Rivian is able to get 1.8 mi/kWh at 75 mph, that would put them near the top of the BEV heap for best highway range in a BEV. They do it with a massive battery, while Tesla and others do it with great aerodynamics.
 

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For this reason most of the displays (in Teslas at least) and most of the programs that track performance and are used for trip planning use Wh/mi.
GM vehicles, as well as many other use mile/KWH, it really doesn't matter. I think GM does a good job of providing clear feedback of range as you are traveling. You get nominal miles remaining, as well as Max and Min miles remaining right on the driver display. It also has a trend vector that can decrease toward minimum or increase toward maximum as you are driving and conditions are changing, such as headwind or grade. If you change climate settings the feedback is instantaneous. I always use the minimum reading and trend vector to determine margin to the next charger and adjust speed as necessary. Trip planners do not always know the weather conditions you will be driving in.
 

ajdelange

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I don't think Rivian will allow us to use the full capacity of the 180 kWh battery pack. Tesla typically does allow most (maybe all) of the capacity to be used, but Ford and other manufacturers do not.
There is lots and lots of confusion over this point. There is a fairly large group of people who are determined to prove that Tesla is somehow cheating by basing their range on the full capacity of the battery whereas all the other OEMs are honest and don't do this. The fact is that "full" and "empty" are arbitrary and are chosen by the OEM. Beyond this wherever the OEM sets them more energy is required to charge the battery between empty and full than what can be taken out in discharging between full and empty (because of internal resistance) and it is often not clear which capacity (charging or discharging) is being discussed. Because the lay public can easily be led astray, intentionally or unintentionally, unless precise definitions of what empty and full mean are given both Rivian and Tesla have stopped disclosing battery capacity.

My XLR + has a rated range of 351 miles and a rated consumption of 282 Wh/mi. Therefore the difference between full and empty is 282*351 = 98982 Watt hour. This is fairly certain with the Tesla. The numbers are derived from the vehicle in my garage.

With the RIT Max the rated range is going to be close to 400 mi and they used to say the battery size was 180 kWh. Putting those two together we get the 450 Wh/mi estimate of the rated consumption and as this is a reasonable estimate we assume that the difference between full and empty on discharge is going to be pretty close to 180 kWh. All that will be available to you just as the full 98 kWh is available to you in a Tesla MX. In neither case do we know where the engineers have put the full and empty marks on the open circuit voltage curve nor how close the empty mark is to 0V nor how close the full mark is to explosion. It might be best to think in terms of the rated range. You will have the full rated range available to you (if your driving matches the EPA protocol).

The reason is clear: they are trying to protect the battery from damage.
That's the reason for setting the full mark low. It isn't a brick wall thing. the higher you charge a battery the more you get into the risk of dendrite formation and the irrecoverable loss of lithium to the SEI. The wise driver only brings his BEV to high SoC for road trips. In daily charging, for example, i only go to 65%. If you charge a Tesla to 90% or more on 3 (I think it is) successive days you will get a warning from the car that you ought to avoid this. If you super charge excessively you also get warnings and in some cases the car will protect itself. You can imagine how well that is received by some. Surprised owners are outraged and the FUD crew are delighted as they think that this is plain evidence of Tesla's malfeasance.

The Mustang Mach-E has a 98 kWh battery, but only 88 kWh is available for moving the car down the road. So all calculations need to be done with the usable capacity, not the battery pack size.
Did they tell you the voltages? If not those numbers are meaningless. So until you figure out what they really mean, which you can do by determining the rated consumption and multiplying by the rated range do your calculations based on miles. You will get, under EPA driving conditions, 100% of the rated EPA range. If you wish to be prudent and operate between 10 and 90% you will get 80% of the EPA range driving under EPA consitions; between 10 and 80%, 70% range etc.

Unless I missed it, I don't think Rivian has announced if they plan to make the entire capacity available or not. My assumption is they will not, and 90% of the total battery capacity is a reasonable estimate.
No they haven't and won't unless they want to play marketing games. The arbitrariness of the full and empty settings allows lots of opportunity for an OEM to do this. You can either push the range wide in the hopes of getting the biggest number and warn drivers to avoid this region (as Tesla does - it's the most sensible approach really) or sandbag or be unclear about whether charge "capacity" or discharge capacity is being specified. Be assured that if you use 70% of the Rivian SoC that you will get 70% EPA range (if you drive as in the EPA profile).

To see if I am telling the truth try some trips with ABRP.
 
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ajdelange

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Here is the math:

180 kWh battery pack x 0.9 = 162 kWh usable battery capacity. (Rivian might allow us to use more capacity than 90% of the full pack, but we have to assume they will not and will follow what Ford and others are doing to protect the battery from damage.)
They will give you 100% of the 180 kW if the rated consumption is the 450 we are estimating. If the rated consumption turns out to be 460 they will give you 100% of 184 kW. The battery will still be protected as you will not be allowed to charge above or below safe cell voltage. They may, as Tesla does, advise against frequent excursion into the upper ranges of SoC (above 90%) but they will not allow you into the unsafe region, however they define that which is also somewhat arbitrary.

162 kWh x 2.5 mi/kWh = 405 miles of range. (This is EPA, not highway.
2.5 mi/kWh is 400 Wh/mi which is a bit optimistic I feel (and I do mean feel) but if you want to use it OK. This says that the discharge capacity of the battery is 400*400 = 160 kWh. You will still get 400 miles EPA range. If you want to pretend that it's really a 180 kWh battery of which they are only allowing you 160 that's OK too. The fact is that you will never know what the battery capacity is but rather only what the distance between 0% and 100% SoC is. And the point is that x% SoC change will give you x% of 400 miles range.

For comparison the Audi E-tron has a EPA rating of 2.27 mi/kWh, so we are assuming the Rivian will be more efficient than the E-tron. Is that reasonable?
That's 440 Wh/mi which is pretty bad for a sedan. The MX consumes 282 Wh/mi. I highly suspect that numbe (440). In the EPA rating speed range the Taycan consuption is not going to be that great. The Rivian is going to have greater Cd and greater frontal area and will probably have a rated consumption of about that magnitude. Porsche would have to screw up motors and inverters pretty badly to have rated consumption 57% higher than the MX. Or they could be sandbagging. Doesn't seem like a good competitive strategy to me.

High speed DC charging slows down significantly when your battery reaches 80% charge.
Each manufacturer has a strategy for tapering charge rate with increasing SoC. What many don't seem to realize is that the car is in control and takes several factors into account so that there is no fixed Tesla taper profile and no profile that Rivian will use on every charge.

When you are on the road, you will likely rarely charge past 80% because it will take too long.
You will rarely do it because if you are smart you know it isn't good for your battery, it is slower and it is unnecessary. If 60% can get to your next charging stop why load 80? Again I think we need to comment here that while this is the case with the Tesla network it may not be so much the case in the CCS network as the big chargers are still pretty thin (father apart).

If you use a route planning tool like A Better Route Planner (ABRP), it will send you to a charger when you reach 10% battery life.
ABRP lets you specify the minimum SoC that is acceptable to you at destination and charging waypoints.


162 kWh x 0.7 = 113.4 kWh of battery available for use between DC fast chargers (70% = 80% - 10%). Then:

113.4 kWh x 2.5 mi/kWh = 283 miles (EPA range, not highway range).
If you are willing to expend 70% of your battery on a leg that leg can be .7*400 = 280 miles under EPA like conditions or 233 miles if you drive at such speed that consumption goes up by 20% re rated consumption.

Beyond the above calculations, which are speculative because Rivian has not confirmed anything, the speculation gets even more difficult. However, based on every single EV that has been built and tested, we KNOW highway range will be lower than EPA range unless the manufacturer has purposely lowered their EPA rating using more conservative testing. Porche did that with the Tycan, because real world testing has people beating EPA range estimates easily. I doubt Rivian has done that though. They probably are providing realistic estimates, like Ford did with the Mustang Mach-E.
Interestingly enough "more conservative testing involves 3 additional tests beyond the bare minimum and running those tests tend to increase he final EPA score.

I don't know what to say about Porsche. Either they are shamelessly sandbagging or a wire was loose to the dyno. In either case someone in the EPA should have caught this.

If you are interested in this stuff you will quickly learn how actual consumption deviates from rated consumption when it's cold, when it's really cold,when it rains and when the headwind is substantial etc. You will be able to predict battery condition, range etc. pretty accurately with no meter other than the car's SoC meter which is, if you think about it, identical to the gas gauge on your ICE car except the E is marked 0% an F is marked 100%.
 
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ajdelange

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GM vehicles, as well as many other use mile/KWH, it really doesn't matter.
As distance travelled is the independent variable Wh/mi (or Wh/km) is clearly the natural unit. As such it makes calculations involving travel a wee bit easier as we can, for example if interested in average performance over several legs we can use arithmetic rather than harmonic averages. That's doubtless why the programs (ABRP) and the cars themselves use it. But as eventually you get the same answer you can do the more laborious harmonic calculation if you want to. I came up in the infancy of computing where divisions took many more ops than multiplication and especially in real time applications, like the ones driving the screens in the cars, every op was precious. I'll still change code to evaluate a polynomial as ((x*d + c)*x + b)*x + a rather than as (a + b*x + c*x^2 + d*x^3) to save a few ops. Also if you do calculations involving the individual loads it such as how the drag load evolves with speed relative to rolling resistance, it's confusing to use the reciprocals. For example if the rolling load is 80 Wh/mi and the drag load 150 but the latter increases to 165 if we speed up 10 mph it's pretty clear what is happening but to express the rolling load as 12.5 mi/kWh and the drag load as 6.6666 mi/kWh so that the total economy is 4.35 mi/kWh is, to my way of thinking much less clear. But if you want to do it that way go ahead. Whatever floats your boat.

Use whatever floats your boat.

Trip planners do not always know the weather conditions you will be driving in.
They never do except roughly in terms of what you put in for forecasts. On the trip the car has historical information and it knows what the terrain ahead is like. Now we get into the question of which estimator is the best to predict how the rest of the journey will go. Tesla apparently uses its knowlege of terrain and what it has in its data base for speed limits for the route to adjust he rated consumption in order to estimate consumption at each point along the as yet to be driven part of the planned route. Of course it cannot know whether a cloud burst is going to arise or whether the wind will shift from quartering to head. Naturally this is all displayed to the driver in terms of kWh and Wh/mi.
 

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I read an article, probably from an author that has an affinity for ICE than EV….he was saying the battery life is 10 years. How do you guys feel about that Stat?
 

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I'm not uncomfortable with the idea that the current crop of batteries may have lost up to 20% of capacity in 10 years but that is going to depend in large measure on how they are charged.
 

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Use whatever floats your boat
I use the MyChevrolet App, I do not use a calculator. I have done some comparisons between ABRP and the MyChevrolet App, and they give me the same answer as far as battery remaining at the next charger. Both take into account the speed limit and the terrain. The app provides real time updates while driving, so that I can adjust if necessary.
 

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I'm not uncomfortable with the idea that the current crop of batteries may have lost up to 20% of capacity in 10 years but that is going to depend in large measure on how they are charged.
can you elaborate on "how they are charged" a bit more...meaning what is the best way to have longevity in these batteries? I may ask Rivian that question....when I talked with RJ back in 2019 he said the batteries would outlast the vehicle...I tend to keep vehicles longer than 10 years (wink)!

BTW thank you for your response!
 

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As distance travelled is the independent variable Wh/mi (or Wh/km) is clearly the natural unit. As such it makes calculations involving travel a wee bit easier as we can, for example if interested in average performance over several legs we can use arithmetic rather than harmonic averages. That's doubtless why the programs (ABRP) and the cars themselves use it. But as eventually you get the same answer you can do the more laborious harmonic calculation if you want to. I came up in the infancy of computing where divisions took many more ops than multiplication and especially in real time applications, like the ones driving the screens in the cars, every op was precious. I'll still change code to evaluate a polynomial as ((x*d + c)*x + b)*x + a rather than as (a + b*x + c*x^2 + d*x^3) to save a few ops. Also if you do calculations involving the individual loads it such as how the drag load evolves with speed relative to rolling resistance, it's confusing to use the reciprocals. For example if the rolling load is 80 Wh/mi and the drag load 150 but the latter increases to 165 if we speed up 10 mph it's pretty clear what is happening but to express the rolling load as 12.5 mi/kWh and the drag load as 6.6666 mi/kWh so that the total economy is 4.35 mi/kWh is, to my way of thinking much less clear. But if you want to do it that way go ahead. Whatever floats your boat.

Use whatever floats your boat.

They never do except roughly in terms of what you put in for forecasts. On the trip the car has historical information and it knows what the terrain ahead is like. Now we get into the question of which estimator is the best to predict how the rest of the journey will go. Tesla apparently uses its knowlege of terrain and what it has in its data base for speed limits for the route to adjust he rated consumption in order to estimate consumption at each point along the as yet to be driven part of the planned route. Of course it cannot know whether a cloud burst is going to arise or whether the wind will shift from quartering to head. Naturally this is all displayed to the driver in terms of kWh and Wh/mi.
Wow. You know computers and boats. How about bass fishing? Lol.
 

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