Possible Tesla Semi mule captured on video

Discussion in 'Tesla' started by Domenick, Oct 11, 2017.

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  1. Last edited: Oct 11, 2017
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  3. Steve

    Steve New Member

    What else could it be really? With that obvious, concealed battery pack, no diesel stacks, and very little sound in the video clip. The acceleration is crazy, too. I think it's interesting to look at the Imgur image and see that area behind the cabin, on the prototype, whereas the mule doesn't have that to house the pack. The fact that both vehicles are in that same previous picture seems telling. I'm curious what others think, see, hear, though.
    Domenick likes this.
  4. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    If you turn up the sound on the video, you can clearly hear a diesel engine starting and idling.

    It's almost certainly not a Tesla test mule, despite what anyone might think. A test mule would not have the diesel powertrain intact and in operating condition.

    What could that box behind the cab covered in what might be beige canvas, possibly be? Heck, it could be nearly anything. Even without hearing the distinctive sound of a diesel truck engine starting, anybody exercising critical thinking should have been skeptical of the claim it's a battery pack.

    Nothing to see here. Move along, move along!
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  5. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    You mean, like this?


    Yeah, like a perfectly standard diesel semi tractor pulling an empty trailer and starting out in a higher gear. That's what they typically do.
  6. Not saying you're wrong, but it seems to me the diesel we hear running is not the one that's the subject of the video. Not positive it's electric, but it's pretty convincing, especially with the supporting evidence.
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  8. Also, good point. Not every tractor has stacks.
  9. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Well, we'll have to agree to disagree. I don't see anything I would call solid evidence, just speculation.
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  10. jim

    jim Active Member

    Hey if I was driving it would have a Stack.
    Thank ya, Jim Stack
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  11. Jack

    Jack Administrator Staff Member

    While it is clearly not a very loud truck, I did hear an ignition. Why is there ignition if it is electric? Is it a hybrid?
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  13. wavelet

    wavelet New Member

    It could certainly be some company's electric mule (Tesla or other); it's possible they haven't yet gotten around to converting the truck brakes to run without an engine takeoff.
  14. Jack

    Jack Administrator Staff Member

    Does this have to do with engine braking? I thought the brakes were air, so maybe a small ICE engine is powering the air compressor?
  15. wavelet

    wavelet New Member

    I also meant air brakes, but AFAIK the air compressor on ICE trucks is always driven by the ICE; it's possible an initial mule to test the drivetrain onlywould still have the original ICE and the original air brakes; later on of course they'd need to convert the braking system itself.
  16. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    Certainly it's possible, but that's violating the principle of Occam's Razor. The simplest explanation is that this truck isn't a Tesla mule.

    It is a capital mistake to theorize before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. -- Sherlock Holmes, "A Scandal in Bohemia" by Sir Arthur Conan Doyle
    Last edited by a moderator: Oct 16, 2017
  17. But but but...

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  18. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    @ Domenick:

    Well, who can argue with logic like that?
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  19. Jack

    Jack Administrator Staff Member

    Is it true that higher speeds = shorter range for EVs? If so, that seems like a large obstacle for EV trucks that will be primarily highway mileage. Diesel engines are the opposite, higher speed = more range.
  20. Pushmi-Pullyu

    Pushmi-Pullyu Well-Known Member

    I suspect that's a misunderstanding of the factors and inefficiencies involved.

    Driving at highway speed tends to be driving at a steady speed. Driving at low speed tends to be stop-and-go. A loaded freight truck, because of the weight it hauls, is subject to even more energy loss due to the inefficiency of constant acceleration and deceleration than is a passenger car in stop-and-go traffic. There is also a lot of efficiency lost in constantly changing gears. An 18 wheeler may have as many as 18 gears or even more, so there's a lot of gear-shifting to get a fully loaded freight truck up to speed after stopping.

    Any vehicle, regardless of what type, is going to take more energy to travel at a steady speed down the road at highway speeds, as compared to -- let's say -- the 25-30 MPH speed used by those trying to set a record for distance. A passenger car traveling at 55 MPH spends half its energy just fighting wind resistance; that's true regardless of whether it's a gasmobile, a BEV, or a diesel car. At higher speeds it rapidly gets worse, because drag increases as the square of speed. Those aiming for a distance record travel at 25-30 MPH because the energy loss from wind resistance is very low at such speeds.

    Much the same applies to a loaded semi tractor-trailer rig. In fact, I've seen claims online that such a rig can improve its fuel efficiency by as much as 15% by installing "skirts" and a "boat-tail" on the trailer, to reduce aerodynamic drag.

    We can be sure that the Tesla semi tractor will have aerodynamics superior to the average diesel semi tractor, and thus lower drag. It's going to be interesting to see if Tesla does anything else to reduce drag when it does a public demo of its BEV semi tractor. Special drag-reducing fittings on the trailer, or a specially built low-drag trailer, could certainly increase efficiency and thus EV range, but fleet operators are unlikely to be interested in buying special trailers. The advantage tractor-trailer rigs is the interchangeability of both tractors and trailers. Lose that, and you lose nearly all your customers.
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  21. Jack

    Jack Administrator Staff Member

    I understand the physics, and I am saying that diesel engines are known to get better mileage/range on the highway than regular gas engines. Furthermore, in any gas engine there is really no efficiency drop off between 25-60 mph. So if a diesel truck was to drive 25mph consistently, it would have a range very similar to a truck driving 60mph. Can the same be said of EV trucks? Is the range of an EV going 25mph different than an EV going 60mph?

    I'm sure Tesla will deliver a product that can drive for extended ranges, but at what cost and how much more efficient will it be?
  22. As
    As Pushmi-Pullyu said, it's about the wind resistance of the vehicle. The engine may be running at the same efficiency, but you won't go as far at higher speeds. And 60 mph is definitely high enough to make a big difference.
  23. Jack

    Jack Administrator Staff Member

    It definitely makes a difference, but not that big of a difference.

    "most cars’ fuel efficiency peaks at speeds from 35 to 60 miles per hour. After 60, though, fuel efficiency does drop significantly"

    Really, all I am asking is this:
    How much does the range of an EV change between 35mph and 50mph?

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