Engineering Explained: F-150 better than Cybertruck for towing duty (over distance)

[ajdelange]

I think the air resistance of the trailer is going to be higher than that. They are typically not very aerodynamic. Just slightly better than a brick, so call it 0.9 (the cyber truck is approaching 0.3, so almost 3x the drag coefficient). If its a 5th wheel, it sits up high, and probably max width, so the combined frontal area will be like 60-80 square feet (2x the CT's 30-ish). Drag is a combination of the coefficient of drag x the area, so that puts the aerodynamic drag of the combo around 5x the CT. Air drag is the bulk of the resistance at highway speeds, so the range will be proportionately lower. I would not be surprised to see it down around 100 miles.

I said that any range estimates I would give would be exceeding crude and I'll continue to hide behind that statement. If we assume that rolling resistance is 20% of consumption (as I did before) and that the CT's consumption un burdened is 485 that implies drag consumption of the CT is 388 Wh/mi. Putting the trailer's drag at 5 times that gives it consumption of 1940 for drag. Our assumption assigned 97 Wh/mi to rolling resistance and we might assume the trailer's rolling resistance consumes twice that as it weighs twice as much (we're still talking the huge 5th wheel rig here) or about 200 Wh/mi. That gives 1940 + 200 = 2140 for the trailer to which must be added the 485 for the CT itself meaning a total consumption o f 2625 Wh/mi. This is 5.4 times the demand for the truck alone and range will thus be less that 1/5th (18.5%) of the CT by itself. For the 500 mi rang model that's 92 miles. But this is also a very crude estimate. Someone who has one of these and want's to get an idea should go out and measure the increase in fuel consumption per mile with his current ICE truck. The measurement won't exactly match what's going to happen with the CT but factors of 5 would certainly be detected.

Note that there are "aerodynamic" trailers made such as the one that I mentioned in #12.

Also note that the towing vehicle shields the trailer to some extent.

Air drag is proportional to speed squared, so the air drag at 75mph is going to be almost double what it is at 55mph. Keep the speed low to get better range.

Do keep in mind that there are other consumers of energy (transmission loss, bearing loss, slip loss) so that wh/mi vs speed does not go as the square of speed as these other forces tend to swamp drag.

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[ajdelange]

The more fuel you burn (ie towing and/or if you drive a lot) .. the more money you save using an EV. Simple.

Not if you are recharging at EA stations.

 

[Cougs]

I am not an experienced person to tell you which vehicle ICE or EV can tow better than the other but I am a scientist and look at the facts.

Advise by TFL Trucks when asked the following: Do You Really Need a Heavy Duty Truck to Tow 9,000 lbs? Ford F-150 vs F-250 MPG Review
They recommended that you always want to buy a truck that does more than you need to tow.

1. They real world (not formulas) tested 2 trucks to tow 9000 lbs.


Truck 1: Ford F150 V10 Cayote capable of towing 9000 lbs and 1600 payload, 395 hp, and about 400 ft-lb torque
a. squat = 2.5 inches b. Noise= 63.8 decibels (<70 is good).


Truck 2: Ford F250 6.7 L Powerstroke Diesel capable of towing over 13000 lbs, possess long wheel base, and payload of 2050 lbs.
a. squat = 1.5 inches b. Noise= 65 decibels (<70 is good).

The Ford F250 performed a lot better than the F150. They may have tested the F150 cayote engine V8. Eventhough the F150 did well it is not recommended to use its maximum capability 9000 lbs. We need to consider hills, wind speed, ice, snow, etc......


2. TFLTrucks has tested real world towing of 7 half ton trucks towing 7000 lbs in 100 miles loop (one was 66 miles loop).


The conclusion is that only Diesel titan cumming, ford 3.0 L diesel, and Ram 1500 2 wheel drive were little above 10 miles/gallon and the rest are between 8-9 miles/gallon. . Keep in mind in this video the trucks has different specs like fule, horse power, rear axle ratios, etc....we are not comparing trucks but we are assessing each on their own merits.

The Cybertruck will have a very good payload (3500 lbs), torque, and structure to tow well if we use it for 7000 to may be 10000 lbs RV.

I will be towing 7000 lbs very aerodynamic RV (small 19 ft Airstream or 19 ft Black Series). All the math suggested by the video listed above is a wash and not the same.

The bottom line the Cybertruck can tow 14000 lbs in town 50 miles or less but in the real world no one is going to use the Cybertruck or any other truck to tow at its maximum capability. NO one.

Everyone knows that EV range decreases by possibly half the range but not by 1/5 like the video suggests. I personelly asked RJ Scaringer Rivian CEO when I attended seattle private party that I will be towing about 7000 lbs how much range do I loose?? he stated that they did not tested towing in real world but it looses range. He did not discourage me from buying a Rivian but we talked about the auxillary battery that they are going to build sometime after the truck is on the roads. I will take 200 miles at a time drive for 3.5 to 4 hours and then take an hour break and move on. In fact why do I need to drive more than 4 hours to go camping??? I would stop sooner than that, camp enjoy that area and move on. After all I am going to be retired when I drive I will not be in a hurry to go anywhere just enjoying American beauty as I travel. Stop, enjoy the area and move on.

I am not going to let anyone discouraging me from buying an EV truck because it is the future, good for the environment, and financially make sense. The truck will last for decades and a battery can be changed, added on, etc... May be Elon will add auxillary batteries in the future.

 

[Keeney]

Someone who has one of these and want's to get an idea should go out and measure the increase in fuel consumption per mile with his current ICE truck. The measurement won't exactly match what's going to happen with the CT but factors of 5 would certainly be detected.

Here is where the terrible aerodynamics of the ICE trucks messes up the ratios. The ICE truck is worse aerodynamically to start with that its not 5x the drag when you add the trailer. It might only be 2x to 3x. My real world towing experience is with a 7000 lb boat. It may be more aero than a 5th wheel camper (at least in the front) and about half the 14,000 lbs. Mileage in my ICE towing that boat is roughly half what it normally is (8-9 mpg vs about 16).

I agree that there are smaller, more aerodynamic campers, but the OP started out pre-supposing a 14,000 lb 5th wheel trialer.

 

[Rancherort]

The biggest issue I see is Tesla constantly avoiding the subject. The model x with even a moderate load drops to 40% of its range. Unless the CT has some crazy new motor or battery design I don't see any advantage or efficiency increase while it's towing. I expect it to lose electrons like crazy when a trailer gets hooked to it. Of course Tesla isn't or wont release that info.

 

[ajdelange]

The biggest issue I see is Tesla constantly avoiding the subject. The model x with even a moderate load drops to 40% of its range.

The Model X which requires about 300 Wh/mi has its range reduced to 40% of its nominal range when the trailer load is 0.6*300/.4 = 485 Wh/mi i.e about 1.62% times as much as the X. Is that a moderate load? Consider towing another x. We know that that takes about 300 wH/mi more and that the range would, therefore, be about half. That's a 5500 pound load. Is that moderate? Yes, compared to a 14,000 lb 5th wheel trailer but there are pretty nice camping trailers which weigh less than half of 5500 lbs. I think we can presume that they would not reduce range to less than 50%.

I have a moderate sized trailer (big enough to haul furniture from Virginia to Quebec. Changes in gas mileage with my Lexus suggests that it takes about 80 Wh/mi to pull this thing. Call it 100 Wh/mi. It would reduce the range of the X to 300/(300 + 100) = 75%. To find out I would have to actually pull it behind the X. I would expect to find consumption up to 400 Wh/mi but I wouldn't expect it to be much different than that.

Unless the CT has some crazy new motor or battery design I don't see any advantage or efficiency increase while it's towing.

No because as I keep trying to make clear the only thing with a major effect on towing range is the power required to move the load relative to the size of the ""gas tank" on the truck. Improving the efficiency of the CT to 95% from the X's 90% isn't going to make an appreciable difference. Going from a 100 kWh battery to a 225 kWh battery is.

I expect it to lose electrons like crazy when a trailer gets hooked to it. Of course Tesla isn't or wont release that info.

You may not understand the physics but Tesla does. They can tell you what the towing range reduction will be if you tell them what the trailer's weight and consumption are. Until they know that they cannot do the calculations and would be fools to throw out numbers based on the simplistic assumptions one is forced to make without that data.

 

[Garden_Aum]

The biggest issue I see is Tesla constantly avoiding the subject. The model x with even a moderate load drops to 40% of its range. Unless the CT has some crazy new motor or battery design I don't see any advantage or efficiency increase while it's towing. I expect it to lose electrons like crazy when a trailer gets hooked to it. Of course Tesla isn't or wont release that info.

I do not know if it is a "isn't or won't" situation with the towing range. I doubt they have the real world data at this time. I hope as they prepare for a final production design they test the CT in a range of conditions and then release the data. They should also test ICE counterparts so that there is something to compare the numbers of the CT to.

 

[Rancherort]

My experience with my own trucks is around 45% loss or so towing a 5000lb car and hauler combo. It really depends on terrain. Tesla had little to say for inquiries into the model x's towing range. The problem i see is that an extended range battery is a must on the dual motor CT.

 

[ajdelange]

My experience with my own trucks is around 45% loss or so towing a 5000lb car and hauler combo.

Seems reasonable. The range will be reduced to r = 1/(1 + T/W) where T is the energy required to tow whatever it is that is being towed some distance (1 mile) and W is the energy required to move the vehicle alone that same distance. If you tow an X behind an X T = W and the towing reduction factor is 0.5.

It really depends on terrain.

Yes it really does. I just found out from another thread that 85% of the people here do not have BEVs. BEV operators are very conscious of the effects of terrain and weather on W and range, Range, R, is R = Usable_battery/ W. For the X, as an example, the battery size is about 100 kWh and W about 0.33 kWh/mi for R = 300 miles. If it rains, and not even very hard, W can shoot up to over 400 and range goes down to around 220 miles. That's without the trailer. Range reduction with rain is caused by the extra energy required of the tyres to push water out of the way and water is actually pretty thick stuff. The trailer has tyres too and so both T and W will go up - approximately to the same extent so that T/W is about the same as is r. But now r is applied to the 220 miles reduced range, not the nominal 300 mile EPA range for an X (pre Raven) and you have probable range of 110 miles towing another X in the rain as compared to 150 miles towing it dry. Cold weather, headwinds, rough road surface, loose gravel, and especially grade have an effect. Then recognize that we are usually comfortable using only 80% of the battery's available capacity (we don't charge from 0 to 100%) thus practical range to tow an X with an X might be 120 miles in dry weather on flat terrain but only perhaps 88 miles if it is raining. Going up hill really eats your lunch.

Tesla had little to say for inquiries into the model x's towing range.

What would you expect them to say? What you experience depends on the trailer (T), the oonditions under which you drive it and your driving habits. All Tesla knows is W and the battery size.

You can, of course, get a rough idea as to what T might be by noting the reduction in range experienced in towing a trailer of interest behind a vehicle for which you know W. It is too bad the guys that made the videos linked in this thread didn't understand this. They made no effort to measure W which they could have done very simply. I found out in the course of investigating this this that truck manufacturers are not required to publish mpg numbers so I couldn't even WAG W values!

The problem i see is that an extended range battery is a must on the dual motor CT.

A load equal to the car's load (T = W) reduces range to 50%. With a nominal range of 500 mi and a practical range of 80% of this we have a potential ability to tow 200 miles under good circumstances recognizing that this might go down to 150 or even less under unfavorable ones and this might be acceptable. And we might suppose that trailers weighing less that the truck itself might require T < W and might be suitable for towing. The decision rests with the buyer.

OTOH if the nominal range is of the vehicle is 300 miles the picture isn't so rosy. Nor is it so rosy for trailers that weigh more than the truck (T > W).
So yes, a small battery in the CT implying a small nominal range (relative to 500 miles) is a problem which could ostensibly be solved by installing a bigger one. But there is more to it than that. The third motor in the 500 mile CT means more available power to accelerate and decellerate the larger total loads associated with towing.

The real problem is that people are relying for guidance on this on folks like the two guys in the videos who clearly don't understand the physics very well. And I guess we might say that the problem is that the problem is complicated enough that some technical background is necessary to understand it. And even those who do can't really make solid predictions because sufficient data is unavailable. The only way I can tell you with any certainty what will happen if you pull a 14,000 lb 5th wheel behind a CT is to get one of each, install the hardware in the bed of the truck and start taking measurements. I''m not likely to do that as common sense and some crude engineering estimates don't suggest that success is likely. But someone will probably eventually do it and then we'll know.

 

[CarsBarsMars]

Skip to the end to avoid two paragraphs of exposition on why I have my opinon......lol.

IMHO as a guy who tows several different trailers weekly, and who usually has a utility trailer behind me about half the work day, you should not buy the CT if your life is trailer heavy unless Tesla makes a trailer with an onboard battery pack. I am not making an anti-EV statement here, just a practical observation that trailering for most people is a very very part time gig and if they are really worried about their ability to tow a 10,000 pound trailer from a hitch receiver for an annual vacation to Florida they should look into renting a truck for the trip. I used to be the guy with the full size v-8 family hauler and the 28 foot trailer full of camping crap out on the expressway living the american dream. That was 2000 out of 18000 miles I drove every year and the rest of the time I was hauling around a ton of extra vehicle that served absolutely no purpose except to keep my mpg around 9 in the kind of city driving I do. I currently drive a mid-size Lexus that I use to tow trailers when I need truck like capacity for work, and it's a much better solution than a full size pickup.

However the CT is just too much the car I have always wanted (since Jeep decided a Gladiator should cost $50,000 wtf) so I am telling myself that increased efficiency justifys the extra 4000 pounds of vehicle. Also, I plan to keep the lexus since I've painted all my trailers to match it and it's honestly the best truck I've ever owned. I'll use the CT for everything else.

So in my opinion, based on lots of real world trailering, is that you do not want an electric vehicle as a frequent trailer tractor. You will never get anything like consistent power use or predictable power use with a trailer attached unless you're on the expressway in a flat part of the country. I would not be frightened about hitching up a cargo trailer to run to the lumber yard or to pick up cabinets. However I would not buy a CT thinking it's going to be my new lifestyle vehicle where i hook up my 9000 pound (dont actually have one) boat and run to the lake every weekend. I am not sure I'd back a CT down a boat launch in any condition....lol. If you start adding up the load, trailer, people, camping gear, AC, iPads, frequent exit and entry ramps for rest stops, wind conditions, traffic, you might find that in a real world long range trailering situation you'll get 25% of the potential max unloaded range. Just my opinion.

 

[ajdelange]

So in my opinion, based on lots of real world trailering, is that you do not want an electric vehicle as a frequent trailer tractor. You will never get anything like consistent power use or predictable power use with a trailer attached unless you're on the expressway in a flat part of the country.

In what way does the fact that the vehicle is electric make things any different from what they would be with an ICE vehicle?

 

[Keeney]

In what way does the fact that the vehicle is electric make things any different from what they would be with an ICE vehicle?

Range will vary considerably depending on the weight and aerodynamics of the trailer, speed of travel, and elevation. So range and recharging will be the largest issue.

Range anxiety is not as big of a deal for an ICE since you can refuel as frequently as needed in numerous convenient locations with less delay.

Conventional ICE trucks are less aerodynamically efficient to start with, so they carry more energy capacity to start with and the ratio of range lost to towing a large trailer is a lesser ratio. That means your mileage in an ICE might go down to 50% or 40% of the non-trailer mileage, while the CT might go down to 25% of its non-trailer range with the same trailer.

If range is an issue, an ICE can be cheaply fitted with larger fuel tanks. There are inexpensive factory options to upgrade from the standard 23 gallon tank to 34 or 36 gallons, and even up to 48 gallons on some models. Plus you can throw a couple hundred gallons of fuel tanks in the bed for about $1500. So even if your mileage goes down to 2 or 3 mpg, you could still get 400-600 mile range.

 

[ajdelange]

I haven't run out of coulombs yet but I have run out of gas. Thus I dismiss range anxiety.

The answer I was looking for is in the last paragraph: you can get a bigger gas tank on an ICE vehicle.

Thus the person considering towing with a BEV needs to do the same thinking as a guy contemplating towing with an ICE truck.

Keep in mind Rivian's patent for the electric jerry can.

 

[Cougs]

RIVIAN patented an auxillary battery that you can fit in the bed of the truck. I personally asked RJ Scaringe the CEO of RIVIAN about it and he stated that the auxillary battery will be available sometime after the release of the R1T but not soon. I am sure that Tesla can do the same. an extra 200 lbs of battery is not a big deal which adds 100 KWH pack easy. These auxillary batteries can be possibly rented in case you just need it for few trips a year or purchased. In addition, scientist are heavily researching a better battery formula that would extend the range and faster charge. All we need is us the pioneers, early adapters to support the manufacturing of the EV trucks and other vehicles which will allow the transition from heavily relying on ICE vehicles to alternative means like EV's. Ice vehicles will continue to be part of the overall means of transportation but not a dominant means. I was listening to a German radio station and the show host stated that Germany already putting aside billions of dollars in order to help their auto makers to transition. The reason is that Germany does not want to loose its heavily reliance on car manufacturing industry. their economy would suffer a lot if they do not move to EV quicker. IT IS COMING!!!!LET US EMBRACE IT.

 

[Cougs]

I WOULD LIKE TO ADD THIS.: MANY NATIONS ARE SUPPORTING EV TRANSITION, POURING $$$, HELPING BUYERS TO REDUCE THE COST OF PURCHASE, ETC...THE US FAILED TO EXTEND TAX CREDITS TO TESLA AND GM YEST THEY WANT OUR TAX MONEY AND OUR VOTE. I AM VERY DISAPPOINTED. YOU HAVE COMPANIES THAT ARE LEADERS IN THE WORLD YET THE US GOVERNMENT ARE TELLING THEM YOU ARE ON YOUR OWN, IT IS NOT OUR FIGHT.