Towing Range Expectations

[MARSROVER]

Not likely. They are doubtless his best estimate of the EPA range. It would be impossible for him to offer a range with towing without specifying the trailer just as it would be impossible for him to offer the EPA estimate without knowing the details of the EPA protocol.

Very true, size/shape/weight makes all the difference and so supplying these types of numbers would be impossible based on the near-infinite number of configurations.

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[Keeney]

The Cybertruck achieves its range by being very efficient aerodynamically. ICE trucks are not nearly as efficient to start with. So when you tow a giant wall of RV behind an ICE truck, the ratio of mileage lost is less because the ICE efficiency is already bad to start with. With the Cybertruck with its 0.30 drag coefficient destroyed by pulling a trailer with double or triple the frontal area and a drag coefficient of 0.90, your range is going to be cut by a significant factor. Like maybe down around 100 miles even if you start with the 500 mile Cybertruck.

 

[ajdelange]

In specifying an EPA range and an EPA rated consumption number, which they haven't done yet, they do specify the towing range for any trailer but it is incumbent on the person who wants to know the towing range to understand enough of the physics to figure it out from the characteristics, measured or specified, for his trailer. Any owner of a BEV with consumption gauges can measure his trailer's Wh/mi demand quite easily by doing the same run on level terrain with and without the trailer attached to his BEV.

One must separate out the effects of going up and down hill. One needs 0.043 Wh/mile-%-kg both for the trailer and the car. To return to the example I started earlier my X weighs 2500 kg, uses 300 Wh/mi and my small trailer requires an additional 100 Wh/mi for drag and rolling resistance. Now if I load it such that it's gross weight it 1000 kg and run it up a 1% grade it needs 1000*0.043*1 = 43 Wh/mi additional. But keep in mind that the car itself is being hauled up that grade and requires additional 2500*0.043*1 =m

 

[ajdelange]

That's really cool. I have approximately 389 questions so I hope you will post the video.

 

[Mule Ferguson]

https://www.electrictruckclub.com/post/expect-towing-to-kill-range-of-electric-pickup-trucks

 

[ajdelange]

The only part I disagree with is

Reduced range from towing is the result of much higher drag, the added friction of more tires on the roadway and, to a lesser extent, the weight of what's being hauled.

And I only disagree with the use of the phrase "to a lesser extent". The inertial and gravity loads can be appreciably larger than the drag and rolling resistance loads under some circumstances (e.g. you tow in hilly country or you tow in stop and go traffic).

 

[BillyGee]

The only part I disagree with is



And I only disagree with the use of the phrase "to a lesser extent". The inertial and gravity loads can be appreciably larger than the drag and rolling resistance loads under some circumstances (e.g. you tow in hilly country or you tow in stop and go traffic).

The energy required to accel or deccel will be the killer, at speed the electric motor weeks out ICE, but constant drag is a huge factor for this calc.

Where a lot of these calc neglect a detail is that ICE is still only getting about a mile per 3.25 kWh (gas) assuming 16.5 mpg on my bigger truck. It gets that with or without a trailer, meaning my overhead goes to waste most of the time. I imagine most oversized trucks face the same issue, so assuming the cybertruck gets similar mileage to the X you'd be getting 1 mile for .32 kWh of energy.

This is assuming towing doesn't totally nuke the mpge.

 

[ajdelange]

The energy required to accel or deccel will be the killer,

It may or may not be depending on driving conditions

at speed the electric motor weeks out ICE,

Please explain what "weeks out" means. I am not familiar with that expression.

but constant drag is a huge factor for this calc.

It can be under some driving conditions i.e. those where drag is large relative to the other loads namely when operating at uniform speed on level roads at high speeds.

Where a lot of these calc neglect a detail is that ICE is still only getting about a mile per 3.25 kWh (gas)

The basic range formula, r = 1/(f+1) in which f is the ratio of trailer loads to tractor only loads measures those loads in terms of energy delivered to the loads from the motor. Thus one is only concerned with the amount of motor output energy that is went to, e.g., wheel slip, not the amount of energy that was needed by the motor to produce the required energy. One could do the calculation with motor input energy by dividing each load by the efficiency of the engine but that factor would appear in every term in both numerator and denominator and thus cancel out.

This is assuming towing doesn't totally nuke the mpge.

Well it does "nuke" the mpge reducing it by factor of 2 or 3 or even more under grade. Isn't that the point of the discussion?

 

[cybertrucktruckguy]

Yes this is my biggest concern as well. It seems Tesla will offer their own trailer with extra battery so my question is which is the better buy? Extra 20K for tri over dual gets you an extra 200 mile range. How much will the battery trailer cost and how much range will that net?

Do you have any reason for thinking that Tesla will create their own trailers with battery? I know we saw one in the photos but I'm wondering if there is any actual sources on the subject. I am wanting to do a video about Cybertruck Towing and that would be a very useful rumor/speculation to confirm.

 

[cybertrucktruckguy]

I live in farm country and I know people who are always towing, however the distance towed is quite short. Usually to the field and back or to get parts or repairs. The CT will accommodate this regularly.

The other area towing is common here is going to the lake. In this case it is to take the trailer to the seasonal lot in the spring and back in the fall. This will take some planning to achieve however it is doable.

Infrastructure improvements will help for sure. With a Tri Motor and 250kwh charging you can go 250-400 miles towing and then charge in 45 minutes to an hour and do it again. If you can tow for 4 hours and then stop for lunch and get on the road and to go another 4 hours you will put in a good day of towing. You may be able to fill your ICE truck, go to the bathroom and grab a gas station or fast food meal for the road in 15 minutes. I have 2 kids and I cannot do this. They need to use the bathroom and get out to move around. My usual fill up takes 15-20 minutes then I have to find a place to eat and let the the kids/dog get some energy out. I am usually stopping for 1 hour when I do stop for gas.

I think the Tri Motor is your only option for long haul towing from an EV today.

I have a similar take on the subject. I think that most towing happens within 3 hours of home base. First the daily routine stuff, which is the majority of towing because of commercial towing. For instance, in our landscaping business, we are towing with about half our trucks EVERY DAY. This is no problem for the CT, even single motor.

Secondly, most rec towing is weekend trips to the lake or trails. Depending on where you're going this is typically 60-150 miles from the places I've here in 'Truckland' and I've lived in both the Midwest and Mountain West. Most times you're going to a campsite with at least 30amp service so recharging once you arrive should be pretty easy.

Again, this should be fine for both Tri and Dual motor. Generally speaking, if you can afford a boat, RV or dirt bikes, you can afford to get at least the dual motor and a lot of the people I know who tow on the weekends can afford 70k on their tow vehicle, no problem (since most of them actually have 50-80k tow vehicles already).

Lastly, At least where I live, it's no problem to rent a 3/4 or 1 ton truck if you gotta haul something a long ways every once and awhile.

 

[ajdelange]

The driving requirement for the CT line is that it should be able to tow a big load (14,000 lbs) a fair distance (100 -200 miles). The TriMotor is designed to do that. Once you have the TriMotor design you can pull out (or, actually, not put in) motors and batteries to produce less capable vehicles which can be sold for less. But keep in mind that the TriMotor is the towing version. Yes, the others can tow but not very far and not as safely. That last point came to me as I was thinking about that third motor. It is there to share the total towing torque but what it is really there for is torque vectoring to nullify sway. I expect this is one of the things Elon is talking about when he speaks of the as yet unappreciated virtues of the design and in the same time period extra software goodies for trailering. If I'm right about this one should be able to tow a 14,000 load without a swan neck or 5th wheel arrangement.

Thus were I engaged in the use of trailers for my business, even for short hauls, I would go the extra distance for the third motor especially knowing that I could write off the extra cost over a couple of years. For longer hauls to the cottage the TriMotor range is going to be needed.

 

[Keeney]

... I was thinking about that third motor. It is there to share the total towing torque but what it is really there for is torque vectoring to nullify sway. I expect this is one of the things Elon is talking about when he speaks of the as yet unappreciated virtues of the design and in the same time period extra software goodies for trailering. If I'm right about this one should be able to tow a 14,000 load without a swan neck or 5th wheel arrangement.

Sway can likely also be damped out by software controlling the steering input - all the Tesla models have that capability.

But sway is not the only reason for a gooseneck or 5th wheel. To stay stable, all trailers have to be set up to have proportionately more weight forward on the tongue - on the order of 10-30% which can be 1000's of lbs for a 14,000 lb trailer. If you put all that tongue weight back on the bumper of the truck, not only can you overload the truck's rear axle, it can act like an unbalanced see-saw and remove too much weight from the front steering axle. You don't want your steering wheels to have a loss of traction and understeer when your 23,000 lb combination is pushing you down hill into a sharp corner.

Bumper pulling of heavy trailers typically requires a weight-distribution hitch setup that levers vertically on the truck to push the front down.

See this article: https://www.gmc.com/gmc-life/trucks/why-tongue-weight-is-important-for-safe-towing

I think the third motor is there to help distribute the motor cooling needs when under sustained load towing uphill and also for 0-60 bragging rights..

 

[ajdelange]

Sway can likely also be damped out by software controlling the steering input - all the Tesla models have that capability.

The usual advice for getting out of a sway situation is to accelerate with no steering input or apply the trailer (only) brake with no steering input and this makes sense from the physics. Modern vehicles (i,e. ones with computer) use torque vectoring but that is limited in ICE vehicles and BEVs like the Teslas that must do this by use of the friction brakes. The TriMotor CT will have much better torque vectoring capability because of the two independent motors without having to waste energy in the friction brakes.

But sway is not the only reason for a gooseneck or 5th wheel.

True.

You don't want your steering wheels to have a loss of traction and understeer when your 23,000 lb combination is pushing you down hill into a sharp corner.

Torque vectoring works during deceleration too.

I think the third motor is there to help distribute the motor cooling needs when under sustained load towing uphill and also for 0-60 bragging rights..

You are partially correct here. The third motor is there to split the load during towing. Obviously this results in less stress on each motor and the reduction gearing but it is also important to recognize that two motors delivering 50 hp each will waste 1/2 as much heat because rotor and stator currents in each will be half what they would be in a single 100 hp motor. It's not really disposing of the heat that is the issue. It is efficiency. And, of course, the big advantage is torque vectoring which will improve towing stability whether one tows with a fifth wheel, bumper or pivot point projection hitch.

 

[Frank W]

Slightly off topic......Personally I am quite happy with a electric vehicle having higher efficiency, better performance, over the air software updates, rethinking everything from the ground up with regards to the building of it and I will go into the CT driving experience with the knowledge that whatever it is that I am towing I will be prepared for a decrease in range. When I am not towing I will be completely satisfied that I am driving a vehicle that is considerably more efficient than a ICE vehicle. I have been on other forums in the past that considered fuel economy (ice) but NEVER to this level. While I fully understand that some of you have advanced understanding/knowledge of this, I would venture to guess that the majority of the people here have no idea what you are talking about imo. I’m really looking forward to getting more accurate information from Tesla regarding the CT.

 

[Keeney]

The usual advice for getting out of a sway situation is to accelerate with no steering input or apply the trailer (only) brake with no steering input and this makes sense from the physics. Modern vehicles (i,e. ones with computer) use torque vectoring but that is limited in ICE vehicles and BEVs like the Teslas that must do this by use of the friction brakes. The TriMotor CT will have much better torque vectoring capability because of the two independent motors without having to waste energy in the friction brakes.

The point about rear wheels maintaining traction with the rear-ward loading of heavy tongue weight on the rear bumper is a good point!

In my opinion, the added stability depends on adding the appropriate software into the feedback loop. Unlike a human, software doesn't need to learn on the job the tricky aspect of how to anticipate the phase delay and can implement the feedback loop needed to overcome the inherently unstable trailering configuration on an ever-vigilant continuous basis without distraction of failure of attention.

Seems a lot easier to me to just use a more stable vehicle configuration to start with. If you are really interest in bumper-pulling a heavy trailer, check out the Hensley Arrow hitch. https://hensleymfg.com/