Cybertruck Towing during cross-country trek

[ajdelange]

Towing just approx. 4000 lbs will more than halve the range alone, if not drop it by 2/3

Can you give us the supporting math for that please? For the third time I will ask that if a CT requires 500 Wh to move itself a mile how can it require more than twice that to tow one? How can a 4000 pound trailer absorb 500 - 1000 watts per mile when a 6000 pound CT only absorbs 500? Where does this extra energy go? Does the 4000 lb trailer have 3000 lbs of batteries on board that are being charged by generators attached to the wheels? Does it have large sails? Are you towing it with the brakes set?

Where he and I differ, is he incredibly believes going from approx. 4000 lbs to 14,000, will make a negligible difference !!

Before anyone says "Whoa, what are you trying to pull here" remember that we aren't pulling something on rails (with the very low rolling resistanve) and we aren't pulling at 4.5 mph in any realistic scenario so that our continuous load would be appreciably more than 60 Wh/mi.

So where was it I said it makes a negligible difference?

Again I offer to go over in some detail each of the load components that go into an EV's consumption and await your response.

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[ldjessee]

I still hold to the point, and politely repeat it for you again, that while towing 14,000 pounds under normal expected, terrain and traffic conditions. ( ie not 4mph on flat ground for the whole journey)
The Cybertruck's 500 mile range will drop severely to about 50 miles !
Towing just approx. 4000 lbs will more than halve the range alone, if not drop it by 2/3 !
Which is aligned with Aj's rule of thumb that EPA 500 mile range will drop to about 187 mile.

Where he and I differ, is he incredibly believes going from approx. 4000 lbs to 14,000, will make a negligible difference !!

The heaviest thing I have ever towed was a 28,000lb helicopter and it burned out the transmission in a pickup truck we used to tow it 300 ft. The electric tug with no transmission pulled the helicopter around no problem. I do not blame the pickup truck for getting wrecked towing the helicopter, its transmission (an automatic no less) was not designed for that kind of load nor the heat it induced.
The electric tug was designed to pull the weight, but not much over 10 mph.

What speed is keeping up with traffic? What amount of slowing down and speeding up do you consider normal? What terrain do you consider normal?

I have lived on both coasts and lived in flat places. My cars mileage has changed based on the terrain I was driving on and how fast I was going. The difference 10 mph made (slowing down) seems to be discounted by people, but I have used it to stretch gas tanks and now batteries.

Yes, AJ's math has almost always checked out, and the one time a mistake was found, he was quick to admit it and apologize. Where is his mistake in his math here? What part do you disagree on? Rolling resistance not being linear? Aerodynamic load not being linear? Pulling against gravity?

Engineering Explained, back in December, showed a worse case scenario, CyberTruck towing 14,000lbs up a 1% grade for 100 miles and using most of the pack for the TriMotor CyberTruck... at 75 mph. At 60mph, it takes less.
He breaks it down into the rolling resistance, the aerodynamics, and the energy fighting gravity going uphill.
(The video focuses more on the Model X, but he does the math for the CyberTruck.)

What was wrong with the math in this video? 100 miles is a lot more than 50 and this is going uphill non-stop.

 

[Geo]

What was wrong with the math in this video? 100 miles is a lot more than 50 and this is going uphill non-stop.

Thanks for referencing the video Lloyd. I had seen it previously.

The analysis is excellent, and I agree with Jason almost everywhere. He is a Legend.
( As a side note, I have disagreed on a couple of his points in previous video’s though )

He thinks the Cybertruck will weigh 6000 lbs, I think it will be a little less, (about 5600 - 5800 lbs)
He thinks the Coefficient of friction, may be 0.3, I expect it will be just a little more

He strenuously points out that his figures don’t include real world externalities, Heating,
Air Conditioning, real world traffic, real world variation in terrain, real world weather.

Note A: 1% grade equals 0.57 degrees, if drawn to scale, the slope would appear as a flat line.
NOT A SLOPE AT ALL !!
Meaning real world terrain would have a far greater impact for certain.
And would be material to his calculations !!!

Note B: Energy consumed in accelerating upto cruising speed is substantial, and will greatly impact
range. So slowing down and speeding up, let alone speeding up from a standstill to cruising
speed will impact range substantially. Jason has not factored in this reality, in his
theoretical calculations. Each traffic light stop," T" intersection, roundabout etc. !


Model X

Jason : "MODEL X CAN NOT DO 100 MILE RANGE." ( 84 Kwh theoretically consumed) at 60 miles per hr.
( I make it at least 102.4 kWh’s required, after real world efficiency factored in, when starting
with his figure. But his figure, doesn’t take into account Note A, and Note B, and would
materially increase further if done so )

Jason’s conclusion reasonably aligns with the TFL guys experience / Videos, when NOTE A
and NOTE B included.

Jason : "You drive for 75 minutes, you charge for 50 minutes !!!! "

Jason : “ It makes the case very hard that this would be able to do this “

Jason’s conclusion reasonably aligns with the TFL guys experience / video’s


Cybertruck

Jason : “ F150 can do this task twice as good as the Cybertruck !”
I make it out even more so for the reasons explained earlier under Model X.

Jason : “145.8 kWh’s consumed to do 100 miles. “

I make it 178 kwh with externalities factored in, when starting with his figure.

However as per Note A, and Note B, factored in, 200 kwh battery capacity will be exceeded.

I conclude that the energy expended in just 1 stopping and then accelerating off a traffic light is not factored into Jason’s equations, and that these REALITY situations are material to the range, that my figure of less than 50 mile range to tow a 14,000 lbs load is quite plausible.

At best it could be a little better, maybe 65 miles of range, in the distribution of possibilities, but in the majority of statistical distribution of trips, 50 miles is more probable.

But considering we're talking about the full range of battery, from 100% down to absolute zero, nobody is in reality going to aim to do that, run it all the way to empty, so once again, in practical terms, less than 50 miles of range will be available when towing 14,000 lbs.


P.S. Interesting to see that Model X towing 5000 pounds down hill consumes more energy than going “uphill” without towing anything at all !

Don’t know if the F150 is a diesel, as it would be even better, diesel fuel has roughly 30% greater specific energy per kg compared to gasoline.

And obviously the Torque inherent from a diesel is significantly greater than a Gasoline engine and comes in much earlier in the rev range.

Good thing most people in reality are not going to try to tow 14,000 lbs with the Cybertruck,
just like most people don't ever test the top speed of their car, its just the warm and fuzzy feeling some people get being able to have bragging rights. I know I will

 

[ajdelange]

The simple facts are this: It takes energy to move your truck. Call it Et. It takes energy to move your load. Call it El. When you pull the load your energy consumption is Et + El which is (El/Et + 1) times greater than Et so that your range will, for a fixed fuel tank size, be reduced by the factor 1/(El/Et + 1) to R0/(El/Et + 1) where R0 is the range of your truck without a trailer. For example, if it takes as much energy to move the trailer as it does to move the tractor your range will be half. If conditions such as a headwind or grade arise which increase Et and so decrease R0 they will doubtless increase El too and so while the ratio may remain the same or nearly the same the range still goes down.

For perspective a CT has an EPA range of 500 mi. That's a practical range of R0 = 375. Simply driving my X at 80 mph reduces its range by an estimated 30% relative to EPA range. Assuming a similar reduction for the CT we might expect practical range reduced to 262 miles and with El = Et practical range would be 131 miles. OTOH, ceteris paribus, if we drove at 60 mph it would go up to 165.

BEV are at a disadvantage relative to ICE because they have small R0. The tests and analyses discussed at length here were done on Model X at the time when EPA R0 was 294 miles. Pull a trailer that requires as much energy as the car to move at 80 mph and you get working range 77 miles. Pull a trailer that requires twice as much energy as the X and it's 51 miles. The X isn't great for towing large loads long distances. The CT is 70% better with its EPA R0 of 500 mi but not, clearly, as good, in this regard as a diesel truck with R0 = 800 miles.

Thus if you are contemplating pulling a trailer with a CT what you need to know is (El/Et + 1). There is really no way to know what this will be and you can argue all day and night as to whether weight or rolling resistance or drag is the main factor (they all are with the dominant one dependent on driving regime). If you have the trailer and a truck you can estimate it by monitoring fuel consumption as you tow it. When I towed a smallish trailer behind my Lexus fuel consumption went up by a factor of approximately 1.5 implying El = 0.5Et and range reduction to 2/3. Several people here have reported doubled fuel consumption (implying El = Et ) with larger trailers. The result obtained in such a test will not, of course, accurately predict what will happen when you actually tow the trailer with a CT but should give you at least a rough idea. Use your estimate of (El/Et + 1) with your insight as to how R0 varies with conditions to see if the CT is compatible with your plans.

 

[Crissa]

The X is also a terrible example for towing large object because it has such a small aerodynamic profile, little wake, and so doesn't have nearly any of the air resistance of El baked into Et..

Not to mention a motor not designed for big towing loads in the first place - smaller motors end up using much more energy to do the same thing a larger one would do more efficiently.

-Crissa

 

[cmugler]

I have a 14' canned ham vintage trailer weighing 2000 pounds and pretty aerodynamic, any estimates on how much that would reduce my range by?

 

[Crissa]

Hard to tell without trying! But it would be one of the better things to drag around behind you,

-Crissa

 

[ldjessee]

I have a 14' canned ham vintage trailer weighing 2000 pounds and pretty aerodynamic, any estimates on how much that would reduce my range by?

Yes, there is software out there that makes pretty good guesses, but you need the frontal area and the drag coefficient. Pictures from dead on front, dead on side, plus measurements might let someone who has such software do some work... but I do not have this software. I have only seen the results of others who have used it.

 

[Luke42]

I have a 14' canned ham vintage trailer weighing 2000 pounds and pretty aerodynamic, any estimates on how much that would reduce my range by?

Tow it behind a gasoline-powered full-sized pickup truck, and see what it does to your gasoline MPG. Then assume a similar impact on the Cybertruck. It's not as crazy as it sounds.

My gasoline-hybrid pickup truck has an unencumbered range of about 450 miles. (25 gallons * 18 MPG.)

When I tow a 4000lb travel-trailer with roughly the same aerodynamic cross section as your trailer, my MPG goes from 18MPG to 9MPG. This means my truck's range goes from 450 miles to 225 miles.

My WAG is that your trailer, while lighter, is still going to have plenty of aerodynamic drag. So, I'm going to wildly speculate that your lighter trailer will take 3/8ths of my range, rather than the 1/2 of my range that the bigger trailer took. This means that my truck would probably get 11.25-ish MPG while towing your trailer, which would result in a range of about 280-ish miles. But I don't really know -- maybe the real range is 330 miles or 220 miles? The error bars are really big with this method.

I'm going to assert without proof that these numbers will be roughly in the neighborhood of what the 500-mile Cybertruck will do. I freely acknowledge that there are important drivetrain and aerodynamic differences between the CT and my GMC Sierra. I also freely acknowledge that I'm doing bad math on numbers I've pulled out of the air. However, I'm also going to assert that the physical affect of the trailer won't be dramatically different between the CT and between a regular pickup truck, because the trailer is still resisting the motion of the tow vehicle with aerodynamic and mechanical drag.

There are lots of details to quibble about which can effect what the numbers ultimately are, but what the CT can do won't be dramatically different from what another pickup truck can do in terms of reducing the drag of a trailer. The big picture is that the truck is yanking on a steel bar, and the thing on the other end of the steel bar will resist motion. When you double your vehicle (length, weight, aerodynamic cross section) by attaching a trailer, you're gonna (roughly) double your energy consumption. The details tweak this picture, but they don't redefine the assumptions.

Just keep the error bars big enough to acknowledge the arguments everyone else is having! But, at the end of the day, there's no magic here -- just a lot of drag.

 

[cmugler]

When towing this trailer with my 2018 bmw x5 diesel I only see about 30% drop which would roughly translate to a 350 mile range with the trimotor, another beneficial factor is in california the speed limit is lower when towing, sometimes when towing my very small utility trailer i get better mpg Regardless even if the range was closer to 250 miles I could live with that

 

[ldjessee]

When towing this trailer with my 2018 bmw x5 diesel I only see about 30% drop which would roughly translate to a 350 mile range with the trimotor, another beneficial factor is in california the speed limit is lower when towing, sometimes when towing my very small utility trailer i get better mpg Regardless even if the range was closer to 250 miles I could live with that

Is the trailer higher than your BMW? Is it wider than the body of your BMW?
If the trailer sits completely in the 'wake shadow' of your BMW (or the CyberTruck), the impact to range will be significantly lower.

 

[ReddykwRun]

When towing this trailer with my 2018 bmw x5 diesel I only see about 30% drop which would roughly translate to a 350 mile range with the trimotor, another beneficial factor is in california the speed limit is lower when towing, sometimes when towing my very small utility trailer i get better mpg Regardless even if the range was closer to 250 miles I could live with that

I've seen a similar effect with river push boats, they will borrow an empty barge to push upriver rather than run without, they get better fuel economy with a barge on the bow.

 

[ReddykwRun]

I have a 14' canned ham vintage trailer weighing 2000 pounds and pretty aerodynamic, any estimates on how much that would reduce my range by?

Great find you have there. If you ever have to re-skin it you don't live very far away from one of the best sources of metal trailer roof and siding material over in Hemet Vally,
41491 E Florida Ave, Hemet, CA 92544

Sheet metal holds up better than fiberglass in my opinion, yea, I am a little biased, I have had to maintain both surfaces.

http://hemetrv.com/ CA

 

[Crissa]

A drive east out of Hemet is long and pretty, too. Can't wait for more chargers out that way.

-Crissa

 

[cmugler]

everyting has been replaced on my 1952 Crown 14, new siding, studs, floor, birch interior walls and cabinets, electric and gas, and windows the only thing original on the trailer is the frame, door and suspension, do you have a source for vintage trailer windows, my wife is rebuilding hers and want to go with something more authentic than what I used