SPECIAL EDITION QUAD-MOTOR Cybertruck rumor

[CappyJax]

The new trailer had almost the same weight but much better aerodynamic.

What part supported your prediction?

"Tesla Model X LR+, 100 kwh, 5,421 lb (2,459 kg), 350 miles range
2021 Apex Nano 194bhs 22', 4,800lbs, 55mph, 800 wh/mi 108 mi between charge"

An increase from 335Wh/mi to 800Wh/mi from a 4,800 pound trailer with a frontal area of 74 sq/ft would mean that a fifth wheel that weighs nearly 3 times as much with a frontal area of 110 sq/ft is going to us a heck of a lot more energy.

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[firsttruck]

"Tesla Model X LR+, 100 kwh 5,421 lbs (2,459 kg), 350 miles range
2021 Apex Nano 194bhs 22-ft 4,800lbs, 55mph, 800 wh/mi 108 mi between charge"

An increase from 335Wh/mi to 800Wh/mi from a 4,800 pound trailer with a frontal area of 74 sq/ft

Are you saying your spreadsheet predicted that at 55mph the results would be:
335Wh/mi for Tesla Model X 5,421 lb (2,459 kg)
and
800Wh/mi for Tesla Model X LR+ 5,421 lb (2,459 kg) + Apex Nano 194bhs 22-ft 4,800lbs

 

[Crissa]

As for range-impact, slip-and-grip...

...Isn't why I mentioned range.

Different torque curves for parallel motors means different energy inputs for different top speeds. That means increased range at speed.

Being able to also use less motor at the low end is just more variables for traction control accuracy.

-Crissa

 

[CappyJax]

Are you saying your spreadsheet predicted that at 55mph the results would be:
335Wh/mi for Tesla Model X 5,421 lb (2,459 kg)
and
800Wh/mi for Tesla Model X LR+ 5,421 lb (2,459 kg) + Apex Nano 194bhs 22-ft 4,800lbs

 

[firsttruck]

Tesla Model X LR+, 100 kwh, 5,421 lb (2,459 kg), 350 miles range
2018 Airsteam Bambi 22', 4,500lbs, 55mph, 489 wh/mi, 177 mi between charge
Able to go about 50 more miles before having to charge using Airstream Bambi.
50% range increase.

489 Wh/mi for Tesla Model X LR+ 5,421 lb (2,459 kg) + Airsteam Bambi 22', 4,500lbs

So how does spreadsheet explain a huge 300 Wh/mi drop in energy use for a trailer that is only 300 lbs lighter in weight?

 

[ajdelange]

Not very adequately. The trailer's mass related loads are complicated in that they can range from very small (appearing only through rolling resistance) to the largest loads depending on terrain and whether you use the brakes (trailer and tow vehicle) or not. Whether you use the brakes or not depends on the speed profile you must follow (I say "must" because if you come round a corner to find yourself behind a vehicle going 20 mph slower than you are you must apply the brakes).

This means that isolated, single calculations, such as come from spreadsheets are usually grossly inadequate for analyzing what to expect when towing. You need a model that follows the dynamics of a drive. If, towing a 4500 lb trailer at 60 for example, you accelerate on the freeway to 60 mph, maintain 60 mph (26.8 m/s) for an hour on level terrain and then coast to a stop your inertial utilization is 0 Wh/mi irrespective of mass. The rolling resistance would consume about 180 Wh/mi. If you must slow from 60 to 40 for traffic or whatever 113.5 watt hours fly off as heat and must be replaced by the battery. If you do that once per mile the driving dynamics add 113.5 Wh/mi for the trip. Changing the weight by 300 pounds would not change the inertial load in the first case but it would increase the rolling load by 12 Wh/mi. In the dynamic case ± 300 pounds would change the load by ±7.6 Wh per cycle and add ± 7.7 Wh/mi if you must cycle once per mile.

Of course this leaves the question as to how we predict trailering performance. About the best I can come up with is to run multiple Monte Carlos using randomly generated speed profiles which, we hope, at least grossly approximate the speed profiles we will actually encounter and look at the statistics from those runs. Those familiar with modeling will know that one adjusts the parameters of the model until he gets the answer he wants so I won't go into any numbers here.

All of this ultimately comes down to the simple fact that you will get what you will get when towing a trailer with the broad observation that you ought not to count on more than half the non towing range. It is also clear that you will get more range by driving at slow, uniform speed.

 

[firsttruck]

Not very adequately. The trailer's mass related loads are complicated in that they can range from very small (appearing only through rolling resistance) to the largest loads depending on terrain and whether you use the brakes (trailer and tow vehicle) or not. Whether you use the brakes or not depends on the speed profile you must follow (I say "must" because if you come round a corner to find yourself behind a vehicle going 20 mph slower than you are you must apply the brakes).

This means that isolated, single calculations, such as come from spreadsheets are usually grossly inadequate for analyzing what to expect when towing. You need a model that follows the dynamics of a drive. If, towing a 4500 lb trailer at 60 for example, you accelerate on the freeway to 60 mph, maintain 60 mph (26.8 m/s) for an hour on level terrain and then coast to a stop your inertial utilization is 0 Wh/mi irrespective of mass. The rolling resistance would consume about 180 Wh/mi. If you must slow from 60 to 40 for traffic or whatever 113.5 watt hours fly off as heat and must be replaced by the battery. If you do that once per mile the driving dynamics add 113.5 Wh/mi for the trip. Changing the weight by 300 pounds would not change the inertial load in the first case but it would increase the rolling load by 12 Wh/mi. In the dynamic case ± 300 pounds would change the load by ±7.6 Wh per cycle and add ± 7.7 Wh/mi if you must cycle once per mile.

Of course this leaves the question as to how we predict trailering performance. About the best I can come up with is to run multiple Monte Carlos using randomly generated speed profiles which, we hope, at least grossly approximate the speed profiles we will actually encounter and look at the statistics from those runs. Those familiar with modeling will know that one adjusts the parameters of the model until he gets the answer he wants so I won't go into any numbers here.

All of this ultimately comes down to the simple fact that you will get what you will get when towing a trailer with the broad observation that you ought not to count on more than half the non towing range. It is also clear that you will get more range by driving at slow, uniform speed.

Most of what you posit does not apply.
The real world tests were done at a steady 55 mph speed on level highway, not extended stop & go in town. There are no large hills or mountains.
They are already slowest speed on the highway because they are only going 55mph. If they go slower because the vehicle in front was even slower their energy usage would drop because there is even less drag and get some regen during the initial slowing process.

Also the factors you mention should increase the energy use (wh/mi) so the spreadsheet prediction of 840 wh/mi should be the low value not the high value.

If the spreadsheet worked properly you could not get such different energy use (wh/mi) differences for minor 300lbs weight reduction on a 10,200 combined weight at steady 55 mph speed.

His spreadsheet does not seem to be accurate.

Seeing what the spreadsheet predicts with this real world example:

Tesla Model X LR+, 100 kwh, 5,421 lb (2,459 kg), 350 miles range
2018 Airsteam Bambi 22', 4,500lbs, 55mph, 489 wh/mi, 177 mi between charge

might help determine where the spreadsheet errors are.

 

[ajdelange]

Most of what you posit does not apply.

All of what I posited applies. You asked where the errors in his spreadsheet lie. I answered that the problem cannot be solved with a spreadsheet and why.

The real world tests were done at a steady 55 mph speed on level highway, not extended stop & go in town. There are no large hills or mountains.
They are already slowest speed on the highway because they are only going 55mph. If they go slower because the vehicle in front was even slower their energy usage would drop because there is even less drag and get some regen during the initial slowing process.

One of the most significant things about towing is that you DON'T get regen. The returned kinetic and potential energies are absorbed by the trailer brakes - not the tow vehicle battery. But if you never decelerate faster than drag and rolling resistance decelerate you that doesn't matter because that energy does "userful" work i.e. overcome drag and rolling resistance. The basic principle is that at constant speed, if the trailer brakes do not come on, mass only matters a little bit through rolling resistance whether that speed be 55 or 60 so evidently you are not following what I posted. You can either go back and re read my post in the hope that you will understand it or realize that it is more complicated than you think, accept that and forget about it.

If the spreadsheet worked properly you could not get such different energy use (wh/mi) differences for minor 300lbs weight reduction on a 10,200 combined weight at steady 55 mph speed.

If the spreadsheet worked properly the difference for 300 lbs would be m*g*f = (300/2.2)*9.8*0.009 = 12 Wh/mi irrespective of speed assuming the coefficient is 0.009 which is representative. This is the rolling resistance difference. There is no difference in inertial load at constant speed if you (or rather if the trailer) doesn't use the brake. If you do the inertial load depends on how you use the brake. That's the physics. Don't model those physics and you don't get the right answer. As you can't model the dynamics of brake use (unless you want to get into Visual Basic programming) in a spread sheet the problem with a spread sheet is that it is not adequate for this problem. I said all this before so my best advice to you at this point is to go back to my previous post and read it for understanding.

His spreadsheet does not seem to be accurate.

It can't be. You cannot predict the stock market by looking at pigeon entrails and you can't predict trailering performance with a spreadsheet beyond making some rough calculations that must be applied quite broadly.

I actually simplified the problem quite a bit. There are losses that depend on the power consumption so you must solve an equation (though it is a linear one) to determine what the actual power consumption is. Thus this problem is to a layman not a trivial problem. If you have training/experience in math, physics, engineering, statistics etc. I can explain it pretty simply but if you don't I can't. And keep in mind GIGO (Garbage In, Garbage Out). It's pretty easy to come up with a fairly robust model of how the various loads sink power but unless you have a good parametric description of each load and of the speed profile you want to study you cannot get an accurate prediction. As it is impossible to have any of that at this point we really can't say more than "Drive slow at uniform speed, don't brake, put as much load in the truck as you can and you'll get about 50%.

 

[ajdelange]

We wonder how Rivian (quad motor), for example, will handle a single motor failure.

[Edit]I sent them an e-mail in which I asked that question but won't hear back until next week.

We got an answer from Rivian but we are still wondering. The respondent said she would have to research that question with the engineering team.

 

[CappyJax]

Most of what you posit does not apply.
The real world tests were done at a steady 55 mph speed on level highway, not extended stop & go in town. There are no large hills or mountains.
They are already slowest speed on the highway because they are only going 55mph. If they go slower because the vehicle in front was even slower their energy usage would drop because there is even less drag and get some regen during the initial slowing process.

Also the factors you mention should increase the energy use (wh/mi) so the spreadsheet prediction of 840 wh/mi should be the low value not the high value.

If the spreadsheet worked properly you could not get such different energy use (wh/mi) differences for minor 300lbs weight reduction on a 10,200 combined weight at steady 55 mph speed.

His spreadsheet does not seem to be accurate.

Seeing what the spreadsheet predicts with this real world example:

Tesla Model X LR+, 100 kwh, 5,421 lb (2,459 kg), 350 miles range
2018 Airsteam Bambi 22', 4,500lbs, 55mph, 489 wh/mi, 177 mi between charge

might help determine where the spreadsheet errors are.

Here are the exact same calculations at 5,000 foot altitude. There is a 233Wh/mile difference from sea level. So you see, unless your references start listing altitude, temperature, headwind/tailwind component, the average grade of the drive, the type of tires, the material of the roadway, and whether or not they had the windows down or the heat pump/AC on, your numbers are completely and entirely worthless for determining the energy consumption when towing with an EV.

The spreadsheet gives a baseline, nothing more, nothing less.

 

[CappyJax]

All of what I posited applies. You asked where the errors in his spreadsheet lie. I answered that the problem cannot be solved with a spreadsheet and why.

One of the most significant things about towing is that you DON'T get regen. The returned kinetic and potential energies are absorbed by the trailer brakes - not the tow vehicle battery. But if you never decelerate faster than drag and rolling resistance decelerate you that doesn't matter because that energy does "userful" work i.e. overcome drag and rolling resistance. The basic principle is that at constant speed, if the trailer brakes do not come on, mass only matters a little bit through rolling resistance whether that speed be 55 or 60 so evidently you are not following what I posted. You can either go back and re read my post in the hope that you will understand it or realize that it is more complicated than you think, accept that and forget about it.



If the spreadsheet worked properly the difference for 300 lbs would be m*g*f = (300/2.2)*9.8*0.009 = 12 Wh/mi irrespective of speed assuming the coefficient is 0.009 which is representative. This is the rolling resistance difference. There is no difference in inertial load at constant speed if you (or rather if the trailer) doesn't use the brake. If you do the inertial load depends on how you use the brake. That's the physics. Don't model those physics and you don't get the right answer. As you can't model the dynamics of brake use (unless you want to get into Visual Basic programming) in a spread sheet the problem with a spread sheet is that it is not adequate for this problem. I said all this before so my best advice to you at this point is to go back to my previous post and read it for understanding.



It can't be. You cannot predict the stock market by looking at pigeon entrails and you can't predict trailering performance with a spreadsheet beyond making some rough calculations that must be applied quite broadly.

I actually simplified the problem quite a bit. There are losses that depend on the power consumption so you must solve an equation (though it is a linear one) to determine what the actual power consumption is. Thus this problem is to a layman not a trivial problem. If you have training/experience in math, physics, engineering, statistics etc. I can explain it pretty simply but if you don't I can't. And keep in mind GIGO (Garbage In, Garbage Out). It's pretty easy to come up with a fairly robust model of how the various loads sink power but unless you have a good parametric description of each load and of the speed profile you want to study you cannot get an accurate prediction. As it is impossible to have any of that at this point we really can't say more than "Drive slow at uniform speed, don't brake, put as much load in the truck as you can and you'll get about 50%.

Physics and the stock market are not comparable. One is quantifiable, the other is speculative. The parameters that are contained in the spreadsheet give a baseline, nothing more, nothing less.

 

[firsttruck]

Here are the exact same calculations at 5,000 foot altitude. There is a 233Wh/mile difference from sea level. So you see, unless your references start listing altitude, temperature, headwind/tailwind component, the average grade of the drive, the type of tires, the material of the roadway, and whether or not they had the windows down or the heat pump/AC on, your numbers are completely and entirely worthless for determining the energy consumption when towing with an EV.

The spreadsheet gives a baseline, nothing more, nothing less.

In previous comments nobody mentioned altitude. What was repeatedly mentioned was steady speed 55 mph, no hills/no mountains. Why do you bring up altitude now. Assumption is sea level. Did you put in altitude 5,000 ft before?
We already mentioned grade (no hills / no mountains) so why now claim it is unknown.
When you did previous spreadsheet you said nothing about temp & wind. I assumed you would using a normal temp (70F) and no wind. So were you using different values?
In previous you made assumptions about tires & roadway. I said 55mph on highway. I assumed you where using reasonable assumptions about U.S. highways not a dirt road in middle of the Baja.

You made repeated assertions about Cybertruck tri-motor 500 mi towing 14,000 pounds would have much much less than 250 mi towing range. You told us your spreadsheet prediction of Cybertruck towing of 2,000 wh/mi was informative but now claim there are too many variables for you to match simple real world existing vehicles in pretty standard environments that thousands of people drive in every weekend during summer vacation season.

 

[firsttruck]

"Tesla Model X LR+, 100 kwh, 5,421 lb (2,459 kg), 350 miles range
2021 Apex Nano 194bhs 22', 4,800lbs, 55mph, 800 wh/mi 108 mi between charge"

An increase from 335Wh/mi to 800Wh/mi from a 4,800 pound trailer with a frontal area of 74 sq/ft would mean that a fifth wheel that weighs nearly 3 times as much with a frontal area of 110 sq/ft is going to us a heck of a lot more energy.

I never said frontal area is 75sq/ft ball hitch travel trailer vs 110sq/ft for 5th wheel.
Where do you get those numbers?

My assertion is that both trailers have similar frontal area but 5th wheel is closer to Cybertruck so the cD will effectively be less than that of ball hitch travel trailer.
Studies from trucking industry confirm that the size of gap between tractor and trailer is significant.

Here is a simple example for rv trailer
difference in cD ( coefficient of drag ) based on tow vehicle to trailer gap
https://teslamotorsclub.com/tmc/threads/ohmmans-airstream-adventures.83350/#post-1893394

 

[CappyJax]

In previous comments nobody mentioned altitude. What was repeatedly mentioned was steady speed 55 mph, no hills/no mountains. Why do you bring up altitude now. Assumption is sea level. Did you put in altitude 5,000 ft before?
We already mentioned grade (no hills / no mountains) so why now claim it is unknown.
When you did previous spreadsheet you said nothing about temp & wind. I assumed you would using a normal temp (70F) and no wind. So were you using different values?
In previous you made assumptions about tires & roadway. I said 55mph on highway. I assumed you where using reasonable assumptions about U.S. highways not a dirt road in middle of the Baja.

You made repeated assertions about Cybertruck tri-motor 500 mi towing 14,000 pounds would have much much less than 250 mi towing range. You told us your spreadsheet prediction of Cybertruck towing of 2,000 wh/mi was informative but now claim there are too many variables for you to match simple real world existing vehicles in pretty standard environments that thousands of people drive in every weekend during summer vacation season.

You can be at 5,000 feet and still be pretty flat. But there are ALWAYS changes in grade. They may be imperceivable at times, but they are there. You can drive from Chicago to Denver and gain over 4,500 feet, and it is flat as hell.

You single data points don't provide any such information, and I was just showing you how there could easily be a large difference in energy usage with a small variable.

I made no "assertion". I provided actual fucking math as to the energy required to move a 14,000 fifth wheel trailer of common size with a tow vehicle at sea level doing 55MPH with tires typical of those on pickup trucks.

Well you use less energy on some trips? Of course! Will you use more energy on some trips? Of course! Try educating yourself instead of arguing with science dude. Are you one of those people who doesn't wear a mask?

 

[CappyJax]

I never said frontal area is 75sq/ft ball hitch travel trailer vs 110sq/ft for 5th wheel.
Where do you get those numbers?

My assertion is that both trailers have similar frontal area but 5th wheel is closer to Cybertruck so the cD will effectively be less than that of ball hitch travel trailer.
Studies from trucking industry confirm that the size of gap between tractor and trailer is significant.

Here is a simple example for rv trailer
difference in cD ( coefficient of drag ) based on tow vehicle to trailer gap
https://teslamotorsclub.com/tmc/threads/ohmmans-airstream-adventures.83350/#post-1893394

https://coachmenrv.com/travel-trailers/apex-nano