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Tesla Semi and Roadster could be relying on a “battery breakthrough”
Elon Musk and Tesla have made some bold claims for the new Tesla Semi and Roadster. Those who understand batteries have been scratching their heads trying to figure out how the company can deliver the specs it’s promising – and concluding that the only possible way is some as-yet-unannounced advancement in battery technology.
Musk says the Tesla Semi will be able to haul 80,000 pounds for 500 miles, and recharge to 400 miles in 30 minutes, which would revolutionize the trucking industry. As for the Roadster, its promised 0-60 acceleration of 1.9 seconds effectively shuts down every one of the world’s baddest supercars, and its touted 620-mile range would be double that of any EV produced to date.
However, industry experts are questioning Tesla CEO Elon Musk’s touted range and charging capabilities, saying the specifications defy current physics and battery economics.
According to Bloomberg, analysts at Bloomberg New Energy Finance point out that Tesla Semi’s announced specs would require a battery capacity of between 600 and 1,000 kilowatt hours (6-10 times the size of the largest Model S battery). Using current technology, an 800 kWh battery pack would weigh over 10,000 pounds and cost more than $100,000. That’s just for the battery – Tesla has said its entire truck will start at $150,000. It seems plain that Tesla is counting on falling battery prices to square the circle. “The first Tesla Semis won’t hit the road until late 2019,” Bloomberg points out. “Even then, production would probably start slowly. Most fleet operators will want to test the trucks before considering going all-in. By the time Tesla gets large orders, batteries should cost considerably less.”
It isn’t just the capacity of the battery that’s causing analysts to wear out their calculators – Musk’s claim that the Tesla Semi will be able to add 400 miles of charge in 30 minutes would require a charging system 10 times more powerful than Tesla’s current Supercharger – which is already by far the most powerful in the industry.
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Tesla Semi Megacharger port could support 1 MW of power.
“I don’t understand how that works,” said Bloomberg New Energy Finance EV Analyst Salim Morsy. “I really don’t.” Tesla’s current generation of Superchargers have a power output of 120 kilowatts and can add about 180 miles of range to a Model S battery in 30 minutes. To meet Tesla’s charging claim for the Semi would require the promised Megacharger to deliver an output of at least 1,200 kW.
Perhaps Tesla’s biggest bombshell is the promise that it will guarantee truckers electricity rates of 7 cents per kilowatt hour, which Bloomberg estimates could translate to fuel savings of up to $30,000 a year. Musk says that adding solar panels and battery packs at the charging stations will account for at least part of the cost reduction. However, BNEF’s Salim Morsy insists that Tesla will have to heavily subsidize those electricity rates – he estimates that Tesla will pay a minimum of 40 cents per kWh. “There’s no way you can reconcile 7 cents a kilowatt hour with anything on the grid that puts a megawatt hour of energy into a battery,” Morsy said. “That simply does not exist.”
Of course, that’s no different from what Tesla does for its current Supercharger network, offering free electricity to many customers, while paying almost $1 per kWh to produce it, according to Morsy’s estimate.
And how about that Roadster? To deliver its promised range of 620 miles, it will need a 200 kWh battery pack, twice the size of Tesla’s largest currently available pack. Mr. Morsy predicts that Tesla will stack two battery packs, one on top of the other, beneath the Roadster’s floor.
Even with a double-decker pack however, it’s hard to escape the conclusion that Tesla is counting on improving battery tech to make the Roadster, like the Semi, feasible. Battery density has been improving at a rate of about 7.5 percent a year, and that’s without any major breakthrough in battery chemistry.
-->“The trend in battery density is, I think, central to any claim Tesla made about both the Roadster and the Semi,” Morsy said. “That’s totally fair. The assumptions on a pack in 2020 shouldn’t be the same ones you use today.”
A massive battery pack not only enables greater range – it’s also a key element in the Roadster’s world-beating 0-60 acceleration. Jalopnik’s David Tracy spoke with battery expert Venkat Viswanathan, a Mechanical Engineering Assistant Professor at Carnegie Mellon, who says that the 1.9-second figure actually seems reasonable.
Viswanathan explains that the power output of a motor is limited by the power draw from each battery cell. Because the Roadster’s pack is double the size, the power draw may not be that much more than that of a Ludicrous Model S.
Viswanathan told Jalopnik that the most modern battery cells offer specific energy of about 240 watt-hours per kilogram. Using that assumption, the Roadster’s 200 kWh battery pack should weigh roughly 1,800 pounds, a huge advance over the previous-generation Roadster. With clever use of lightweight materials, the Roadster could still come out under the nearly two-ton curb weight of the Nissan GT-R, an acceleration benchmark among sports cars.
Viswanathan concludes that a 0-60 time of 1.9 seconds and a range of 620 miles are quite feasible, although there are several other factors that will come into play – much depends on the vehicle’s tires and aerodynamics.
-->Meanwhile, at least one analyst thinks Tesla’s latest revelations (or claims, or fantasies, depending on your point of view) have implications that go far beyond the Semi and the Roadster. Michael Kramer, a Fund Manager with Mott Capital Management, told Marketwatch that he suspects improved battery capacities and charging times could make their way into all future Tesla vehicles.
“I’d have to imagine that Tesla has figured out how to put this technology on all of their cars, which means every car could get a full charge in under 30 minutes,” Kramer wrote. Once the Model S “is equipped with the 200 kWh battery pack in the new Roadster, which I can’t imagine is too far down the road, the range issue for the Tesla is officially dead.” (Elon Musk has said that Models S and X will not get physically larger packs, but improved energy density could increase capacity while keeping the size of the pack the same.) Someday soon, Kramer says, “The Model S would likely be able to drive further on one charge than a car on a full tank of gasoline.”
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Note: Article originally published on evannex.com, by Charles Morris
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News
Tesla Semi factory looks almost complete during Thanksgiving weekend
Based on recent drone videos, the Tesla Semi factory looks practically ready to start operations.
It appears that the Tesla Semi factory near Giga Nevada is already hard at work preparing for the initial production of the Class 8 all-electric truck. This was, at least, hinted at in a recent drone flyover of the facility from a longtime watcher.
The Tesla Semi factory after Thanksgiving
Drone operator and Tesla Semi advocate @HinrichsZane recently shared some footage he captured of the upcoming facility during the Thanksgiving weekend. Based on his video, it appears that Tesla gave its employees in the area the weekend off. One thing is evident from the video, however, and that is the fact that the Tesla Semi factory looks practically ready to start operations.
The Tesla Semi watcher did point out that the electric vehicle maker is still busy bringing in production equipment into the facility itself. Once these are installed, it would not be surprising if initial production of the Tesla Semi begins.
A new Tesla Semi
The upcoming completion of the Tesla Semi factory near Gigafactory Nevada seems all but inevitable in the coming months. What would be especially interesting, however, would be the vehicles that would be produced on the site. During Elon Musk’s presentation at the 2025 Annual Shareholder Meeting, a glimpse of the production Tesla Semi was shown, and it looks quite a bit different than the Class 8 all-electric truck’s classic appearance.
As could be seen in the graphic from the CEO’s presentation, the updated Tesla Semi will feature slim lightbar headlights similar to the new Tesla Model Y, Cybertruck, and the Cybercab. Tesla also teased a number of aerodynamic improvements that increased the truck’s efficiency to 1.7 kWh per mile. Extended camera units, seemingly for FSD, could also be seen in the graphic.
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Tesla scores major hire as Apple scientist moves to Optimus team
Chen, who advanced from individual contributor to technical lead during his time at Apple, noted that he was blown away by Tesla’s efforts and synergy.
Former Apple research scientist Yilun Chen has left the tech giant to join Tesla’s Optimus AI team. Chen, who advanced from individual contributor to technical lead during his time at Apple, noted that he was blown away by Tesla’s efforts and synergy.
Apple veteran closes a major chapter
In a farewell note, Yilun Chen reflected on his tenure at Apple as a period defined by rapid growth and exposure to notable internal projects, some of which remain unreleased. His roles spanned engineering, research, early product incubation, and hands-on prototyping, allowing him to build expertise across both mature and emerging teams.
Chen credited mentors, colleagues, and cross-functional collaborators for shaping his trajectory, calling the experience unforgettable and emphasizing how each team taught him different lessons about scaling technology, guiding product vision, and navigating fast-moving research environments. “Each role has offered me invaluable unique lessons… My deepest gratitude goes to my colleagues, mentors and friends,” he wrote.
Tesla’s Optimus lab secured the hire
Chen said the move to Tesla was driven by the momentum surrounding Optimus, a humanoid robot powered by LLM-driven reasoning and Physical AI. After visiting Tesla’s Optimus lab, he admitted that he was “totally blown away by the scale and sophistication of the Optimus lab and deep dedication of people when I got to visit the office.”
His first week at Tesla, he noted, involved spontaneous deep-tech discussions, a flat team structure, rapid prototyping cycles, and what he called a “crazy ideas with super-fast iterations” culture. Chen emphasized that the team’s ambition, as well as its belief that humanoid robots are now within reach, creates an energy level that feels aimed at changing the world.
-->“You can feel the energy to change the world here,” he wrote in a post on social media.
Elon Musk
Elon Musk gives nod to SpaceX’s massive, previously impossible feat
It was the booster’s 30th flight, a scenario that seemed impossible before SpaceX became a dominant force in spaceflight.
Elon Musk gave a nod to one of SpaceX’s most underrated feats today. Following the successful launch of the Transporter-15 mission, SpaceX seamlessly landed another Falcon 9 booster on a droneship in the middle of the ocean.
It was the booster’s 30th flight, a scenario that seemed impossible before SpaceX became a dominant force in spaceflight.
Elon Musk celebrates a veteran Falcon 9 booster’s feat
SpaceX completed another major milestone for its Smallsat Rideshare program on Friday, successfully launching and deploying 140 spacecraft aboard a Falcon 9 from Vandenberg Space Force Base. The mission, known as Transporter-15, lifted off two days later than planned after a scrub attributed to a ground systems issue, according to SpaceFlight Now. SpaceX confirmed that all payloads designed to separate from the rocket were deployed as planned.
The Falcon 9 used for this flight was booster B1071, one of SpaceX’s most heavily flown rockets. With its 30th mission completed, it becomes the second booster in SpaceX’s fleet to reach that milestone. B1071’s manifest includes five National Reconnaissance Office missions, NASA’s SWOT satellite, and several previous rideshare deployments, among others. Elon Musk celebrated the milestone on X, writing “30 flights of the same rocket!” in his post.
Skeptics once dismissed reusability as unfeasible
While rocket landings are routine for SpaceX today, that was not always the case. Industry veterans previously questioned whether reusable rockets could ever achieve meaningful cost savings or operational reliability, often citing the Space Shuttle’s partial reusability as evidence of failure.
-->In 2016, Orbital ATK’s Ben Goldberg argued during a panel that even if rockets could be reusable, they do not make a lot of sense. He took issue with Elon Musk’s claims at the time, Ars Technica reported, particularly when the SpaceX founder stated that fuel costs account for just a fraction of launch costs.
Goldberg noted that at most, studies showed only a 30% cost reduction for low-Earth orbit missions by using a reusable rocket. “You’re not going to get 100-fold. These numbers aren’t going to change by an order of magnitude. They’re just not. That’s the state of where we are today,” he said.
Former NASA official Dan Dumbacher, who oversaw the Space Launch System, expressed similar doubts in 2014, implying that if NASA couldn’t make full reusability viable, private firms like SpaceX faced steep odds.
Tesla Semi factory looks almost complete during Thanksgiving weekend
Tesla scores major hire as Apple scientist moves to Optimus team
