Musk Says Tesla Semi Specs Are Better Than Reported

Tesla Semi


We’ve really only got one spec to go on, so Tesla CEO Elon Musk must be referring to that.

Tesla’s soon-to-be-revealed Semi is still shrouded in secrecy. In fact, the only reported figure we’ve come across is a range estimate.

The upcoming Tesla semi truck is expected to have 200 to 300 miles (320 to 480 km) of range with payload, according to an exclusive report from Reuters. From the Reuters report:

“Tesla’s electric prototype will be capable of traveling the low end of what transportation veterans consider to be “long-haul” trucking, according to Scott Perry, an executive at Miami-based fleet operator Ryder System Inc (R.N). Perry said he met with Tesla officials earlier this year to discuss the technology at the automaker’s manufacturing facility in Fremont, California.”

“Perry said Tesla’s efforts are centered on an electric big-rig known as a “day cab” with no sleeper berth, capable of traveling about 200 to 300 miles with a typical payload before recharging.”

So, after Musk took to Twitter a few days ago to state that “Semi specs are better than anything I’ve seen reported so far,” we are now able to assume, we believe, he’s referring to range. Here’s the Tweet:

Less than 300 miles of range seemed like a bit of a let down to us, so hopefully the CEO’s reference is in regards to range. But it takes a lot of kWh to move a big rig (or any heavy commercial vehicle) hundreds of miles. How much battery capacity is required? Well, that depends on a lot of factors, but just recently Cummins announced that its 560-kWh setup in a BEV bus would provide only 224 miles of real-world range.

Category: TeslaTrucks

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28 responses to "Musk Says Tesla Semi Specs Are Better Than Reported"
  1. Will says:

    If it’s true, the charger have to be overhead like thise new electric byses to be feaseable. Quich charge in 15 min

    1. Windbourne says:

      First off, a simple battery swap would solve that issue.
      However, where are you getting 15 minute charges for buses?

      1. Pushmi-Pullyu says:

        1. A battery swap station, especially for a battery pack as large and heavy as a long-range BEV semi needs, won’t be “simple”.

        2. I think he’s talking about Proterra’s 500 kW bus charger, which does indeed use an overhead arm to connect to the bus. But the bus is flat on top, which Tesla’s BEV semi apparently isn’t… so I dunno if they’ll use a similar setup.

        A 15 minute charge with Proterra’s bus charger? Heck, this InsideEVs’ article claims it’s 10 minutes!

    2. Bacardi says:

      There is an endless demand for trucks with this range, it doesn’t need to travel coast to coast…

      1. Pushmi-Pullyu says:

        The question is how large a market that a hypothetical mid-range or long-distance BEV semi tractor would attract. Sure, there are fleet operators who would buy a semi tractor that can only service short-haul or medium-haul routes, up to 200-300 miles, but can’t handle long-haul routes (at least not without relay staging or battery swapping).

        And of course, there are fleet operators — and probably the majority of independent truckers — who would never consider a truck that can’t go 700+ miles in a shift.

  2. Steve says:

    It’s Monday, time to artificially pump the stock.

    1. John says:

      It’s Monday, time to visit InsideEV’s to bash Tesla..

      1. ffbj says:


      2. ClarksonCote says:

        Haha, the bashers and the lovers are both equally insane. 😉

        1. Will says:

          So true, how up did the stock went.

        2. John says:

          Curious if you categorize my comment as insane?

        3. Pushmi-Pullyu says:

          Well, speaking as a Tesla fan, the word “fan” is short for fanatic… 🙂

          But if all it takes to be judged “insane” is to be a Tesla fan, then we inmates have most definitely taken over the asylum! 😀

      3. needa says:

        Well what do you call that tweet? He could have ignored. He could have said wait and see. He could have said a lot of things that didn’t make it look like the Semi is going to be leaps and bounds better than anything reported so far. TBH I just don’t see how it can be.
        There is only so much room to put batteries and physics can only be pushed so far. We already know what is in the Mod3. We pretty much know efficiencies. Add up what we know and we might see a few extra miles from the reveal.
        Musk is good at over-hyping a product up until reveal. Then the goods come out in black and white and we are able to see for ourselves that not everything he said is going to come true.
        I hope I am wrong btw. But I think we all know that I’m not.
        Expecting a quick trolling retort as you did above, but would be thrilled if there were an actual conversation.

        1. Pushmi-Pullyu says:

          There is no engineering barrier to putting a larger battery pack into a BEV semi tractor; significantly larger than would be needed for a 200-300 mile range. Size isn’t an issue. Weight and cost are issues, but not space.

          I’ll repeat a section of my famous (or infamous) “Napkin Math 1.0″ ballpark analysis for a generic (not necessarily Tesla) BEV semi tractor:


          (revised May 30, 2017)

          FACTS & FIGURES

          A modern diesel semi pulling a load gets 6.5 MPG; therefore uses 0.1538 gallons of diesel per mile

          1 gallon of diesel contains 40.7 kWh of energy

          1 gallon of diesel varies in weight between 6.85lbs. and 7.5lbs per U.S. gallon, depending on temperature. (I’m going to use the figure of 7.1 lbs/gallon)

          diesel semi typical engine weight 2880 lbs

          Eaton Fuller 18-speed transmission weight 738 lbs

          Tesla Roadster upgrade battery pack: 70 kWh in ~10 cubic feet

          standard sized semi trailer dimensions: 110″ high x 96” wide, or 9.167′ x 8′

          DOT weight limit for a six-axle semi tractor-trailer: 80,000 lbs

          Typical price of a relatively high-end new semi tractor: $150,000

          Typical trucker may drive as much as 600-700 miles in a day, and can legally drive up to 11 hours per day.

          * * * * *


          What we need is a BEV battery pack for our semi tractor which will allow it to pull a load for ~750 miles. This should allow the trucker to complete a daily run on one charge. We assume at the end of the run either the battery pack is swapped out for one that’s charged up, or the pack is charged during the hours the trucker is sleeping. Either way, we avoid the need for fast charging and very high current.

          Our hypothetical BEV semi will have an energy efficiency 2.6 times that of a diesel semi. (An EV car is about 3.5 x as energy efficient as an average gasmobile, but diesel engines are about 30-35% more efficient than gas engines.)

          Therefore, our BEV semi pulling a load needs (0.1538 x 40.7 / 2.6 =) 2.4 kWh of energy to run 1 mile.

          Estimated weight of a 2016 Tesla battery pack using 18650 cells: 11.5 lbs / kWh

          Estimated price for a Tesla battery pack (not just the cells): $180 / kWh

          * * * * *

          We need to look at three limiting factors for the BEV semi tractor’s large battery pack: Space, weight, and cost.


          The space behind a long-haul trucker’s cab, the space now devoted to storage and sleeping space, is about 4.1 feet long, at least on the diagram I looked at; I’m assuming the height and width are the same as a typical semi trailer. (At least, the dimensions should be close enough for this ballpark estimate.)

          Let’s use that space for the battery pack. I don’t see losing this space as a problem. Since we no longer need a long nose for the diesel engine, which isn’t there, we can shove the cabin forward, and leave room for the battery pack behind. The tractor now looks more like a “cab-over” tractor with an extended space behind the cabin, rather than a long-nose tractor.

          So I estimate that space at 4.145 x 9.167′ x 8′ = 303.977 cu.ft.

          An upgraded Tesla Roadster’s battery pack has 70 kWh and measures ~10 cubic feet.

          Assuming a similar configuration, that gives us (303.977 / 10 * 70 =) 2127.8 kWh.

          At 2.4 kWh per mile, that’s 886.6 miles.

          This is comfortably beyond our needs of ~750 miles.

          Space isn’t an issue.

          1. needa says:

            I don’t see them taking up the inside of the cab for batteries. Even short haul truckers need a place to sleep. It is common practice for a short haul truck to end it’s day at the destination at night, while waiting till morning for someone to come in and unload. They don’t have the luxury cabs that long hauls have… but it is still enough for a bunk. Looking at the leaked pic… you can see three sections. Front, cab, and then the flaps that extend out to keep the wind from getting in between the trailer and cab.

            What I didn’t think about was their ability slap a couple of powerwalls on the back of the cab (within the flaps). Not saying powerwalls themselves.. but a big metal box standing vertically filled with batts. They could put a couple. Increasing capacity around 50kWh. That would increase the range some. But I wonder about safety concerns if they do that. They would have to be built with some heavy gauge steel to make sure they don’t get damaged from day to day use. Talking trailer connection mishaps. And judging by the pic… that isn’t going to happen anyways.. they would need more space than what those ‘flaps’ are giving.
            I also don’t think you can just assume that since an electric motor is 2.6x more efficient in a car… that that translates over to an 80k lb truck rolling down the road at 70mph. There is also going to be loads of power lost to heat in those batteries.
            They could also stack two packs on top of each other in the chassis. I didn’t think about that till I hit ‘post’ yesterday.

            It seems like we were expecting 180-200 miles on the Semi before and you are correct… they can be more creative with where the batteries go. I’d be totally impressed if it were able to do 250-300, loaded down. And will happily eat my words if it does.

  3. F150 Brian says:

    Of course they will focus on the day cab, an automated driver does not need to sleep. Just need a seat for the co-pilot until fully automated mode is certified

    1. Bacardi says:

      Musk said it’ll be “really fun to operate”…What does that mean? Could mean fun to drive but I don’t understand why he used the word “fun”, perhaps it’ll have a quicker 0-60 than other trucks…It appears it will have a cab vs being fully autonomous…

      1. Pushmi-Pullyu says:

        Elon Musk is quoted as saying “This will be a very spry truck… You can drive this around like a sports car.” (source below)

        But yeah, I think anyone who drives such a truck for a living would find the “fun” would wear off pretty quickly.

        OTOH, Tesla said their BEV semi truck would be a fully autonomous vehicle… so why does it even have a windshield? If it really is fully autonomous, then there should be no need for a cabin. Perhaps Elon is assuming regulatory requirements for someone sitting inside to monitor the truck, even if it doesn’t need a driver.


  4. philip d says:

    Cummins’ .4 miles per kWh for a bus seems way on the low side.

    I’m betting Tesla will be able to get .6 miles per kWh under normal conditions from a loaded tractor trailer which would give it a 300 mile range with a 500 usable kWh pack. Or even .5 miles per kwh in a 600 kWh usable pack.

    I would think they would engineer it to hit 300 miles which is more than enough for the high end distance for short haul trucking.

    80% of annual transported tonnage is hauled 300 miles or less.

    1. Windbourne says:

      Cummins is better efficiency than BYD,
      but less than Proterra.

    2. Pushmi-Pullyu says:

      A city bus does not usually operate at highway speed, nor does it haul around up to 80,000 lbs. of cargo.

      My own “Ballpark Feasibility Case for BEV Semi Truck” analysis used the premise of 2.4 kWh for 1 mile, which would be 0.416667 miles per kW.

      It’s quite reasonable to assume that Tesla’s superior EV engineering, especially the streamlining, will improve on that, by perhaps 15-20%. A 20% improvement would get that up to exactly 0.5 miles/kWh.

      I’m quite skeptical of a claim of 0.6 miles/kWh for a truck hauling a standard semi trailer, with anything close to a full load, at highway speed.

      Now, there are ways Tesla could achieve that, such as by using a special streamlined trailer. But that would very severely limit the market for such a truck. The reason that tractor-trailer rigs are used so much is that any tractor can haul any trailer. If you limit the market to only specialty trailers, then most of your market disappears. Very few trucking fleet owners would buy a truck that can use only specialized trailers.

  5. Windbourne says:

    BYD buses take about 3-4 kwh / mile.
    Proterra takes about 2-3 KWH / mile.

    So, assuming that a truck gets up to speed and stays there, it might take 4-5 kwh to travel a mile.
    Assuming 500 miles, would then require 2000-2500 kwh.
    Not a small amount even with lithium.

    1. Pushmi-Pullyu says:

      Windbourne said:

      “So, assuming that a truck gets up to speed and stays there, it might take 4-5 kwh to travel a mile.”

      The figures you’re using for energy consumption are much higher than I’ve seen in various other analyses, including my own. If city buses really do use 3-4 kWh of electricity per mile, then they must be amazingly inefficient for EVs.

      Average real-world consumption by the average modern diesel semi pulling a load on a long haul route is 6.5 MPG, or 0.1538 gallons of diesel per mile. 1 gallon of diesel contains 40.7 kWh of energy, so that comes to 6.26 kWh per mile. If an EV powertrain can’t haul a load at better than twice the efficiency, then something is very wrong with the engineering!

  6. Bacardi says:

    The distance between the gigafactory in Sparks NV and their assembly plant in Fremont CA are about 240 miles apart…It’ll be at least that distance (with a load)…

    Personally I don’t understand why they want to open additional gigafactories, simply expand on the existing one, the land is still cheap…

    1. Mikael says:

      Because China… Because Europe…

  7. Mike says:

    Sub 5 second 0-60 and multiple motors. Plus multiple Supercharger hook ups.

  8. Don Zenga says:

    200 mile range is good enough for many short distance trips. But first I hope they get the Model 3 production up to full speed.

  9. SJC says:

    There are companies that have built brands making big rig tractors, will owner/operators go for Tesla? As the wise man said “we will see”.