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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.
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
Tesla CEO Elon Musk certainly tipped off some details of the Tesla Roadster event with a broadening of information regarding the company’s decision to delay the unveiling for two weeks.
For years, people have speculated about what the Roadster will be capable of. While there have been plenty of things said about what it *could* do, we have not seen or been told by Tesla what it will actually be capable of.
However, over the past few days, Tesla’s weather updates have truly pushed the speculation into Plaid Mode, basically all but confirming the car will have some sort of aerial capability — whether that would be hovering or fully flying remains to be seen — but it definitely seems that it will be able to leave the ground intentionally.
“Because this event can only be held outdoors…”
Tesla posted on Monday that it would delay the Roadster event until October 15, and it indicated that it had to do this because the event “can only be held outdoors.”
With the potential SpaceX collaboration to develop cold-gas thrusters that will help the vehicle go airborne, doing this indoors is probably not a safe, or even plausible, possibility.
Roadster event update
We’ve been tracking the weather closely with local meteorologists, but given the severe conditions predicted & because this event can only be held outdoors, we’ve made the difficult decision to reschedule.
New date is October 15. Additional details to…
— Tesla (@Tesla) September 28, 2026
FAA Airspace Restriction
The FAA gave Tesla a Temporary Flight Restriction (TFR) for 10,000 feet above ground level, much higher than the typical 2,000-foot restrictions that are usually placed at SpaceX’s McGregor, Texas site.
Tesla Roadster event requires restricted airspace, and the FAA obliges
Some have said that this massive increase is due to Tesla’s need to restrict unauthorized drone use for spying on the event.
Elon Admits High Winds
“Due to high winds, the new Roadster demo is postponed by 2 weeks,” Musk said in a post on X yesterday.
Due to high winds, the new Roadster demo is postponed by 2 weeks https://t.co/dV3ojDh1iT
— Elon Musk (@elonmusk) September 30, 2026
A reply reading, “What’s strong wind got to do with a car demo with four grounded wheels?” was directly below Musk’s post, satirically and sarcastically probing for more details.
All signs are pointing toward an aerial demonstration for the Roadster.
Tesla has secured $30 billion in fresh credit lines from Citibank and Wells Fargo in an effort to scale its biggest current projects.
Tesla agreed to a $20 billion three-year delayed-draw term loan facility from Citibank, it announced on Tuesday. Additionally, it signed a five-year, $8 billion revolving credit facility and a $2 billion, 364-day term credit facility with Wells Fargo.
In a filing with the Securities and Exchange Commission (SEC), that it “may draw” from the $20 billion delayed-draw term “from time to time” and “no more than ten times during the 18 months following the closing date.” This loan matures on September 29, 2029.
The five-year revolving facility from Wells Fargo will also be accessed by Tesla “from time to time,” and will become due and payable on September 29, 2031. Tesla can request two separate one-year extensions.
On the $2 billion, 364-day revolving loan, it becomes due and payable on September 28, 2027. Tesla can also increase its additional commitments to an additional $4 billion across the Revolving Facilities. This would increase the total facilities to $14 billion. Tesla said it does not plan to utilize any of these loans in 2026.
Tesla plans to utilize the money to help prop up its ambitions to scale its biggest products, each of which is either in early launch phases or still in development. Of course, we’re talking about Cybercab and Semi, which have launched, and Optimus, which is still under heavy development and working toward initial release.
All three Tesla products have one thing in common: they’ve all required Tesla to build new manufacturing lines for them.
For the Semi, Tesla built a brand new factory in Sparks, Nevada, adjacent to the Tesla Gigafactory. For Optimus, Tesla sunset Model S and X production at the Fremont Factory, which brought an end to the two flagship models, thus creating manufacturing space for the humanoid robot. Finally, Cybercab is being built at Gigafactory Texas and officially entered production earlier this year.
The cash will help Tesla bolster its finances for the continuing development of these products. Tesla said that it forecasts its CapEx to be over $25 billion, up from just over $8.5 billion last year. These loans surely help with that spending.
Elon Musk
Elon Musk and Trump are closer than ever, and Tesla could be the big winner
Elon Musk sat beside Trump as AI leaders signed a voluntary White House safety accord.
Elon Musk had the seat right next to President Donald Trump on Tuesday as the White House hosted the leaders of America’s biggest artificial intelligence companies for a lunch that ended with a voluntary industry accord on AI safety.
A seating chart Trump posted on Truth Social placed Musk at the president’s left in the East Room, with Nvidia CEO Jensen Huang on his right, according to an Associated Press reporter. Anthropic CEO Dario Amodei, OpenAI President Greg Brockman, Meta’s Mark Zuckerberg, Google’s Sundar Pichai, Microsoft’s Satya Nadella and Amazon founder Jeff Bezos also attended, along with Vice President JD Vance and House Speaker Mike Johnson.
🚨 Elon Musk is currently speaking to the media alongside President Trump after a meeting with AI Leaders in Washington today
Trump says AI is now being called “Super Intelligence” or SI pic.twitter.com/woJJqUVP9B
— TESLARATI (@Teslarati) September 29, 2026
After the lunch, Trump told reporters outside the West Wing that the executives had signed “The White House Accord on Superintelligence: A Joint Commitment on Frontier SI Responsibilities.” Johnson described it as a voluntary statement of principles built on “robust internal controls and layers of internal and external review,” while Zuckerberg said company boards would independently review reports from outside auditors. Trump called the document “morally binding,” said he would name a new AI czar within days, and signed an executive order formally renaming artificial intelligence “super intelligence,” CNBC reported.
Musk was not in the room for Tesla alone. Since SpaceX absorbed xAI, he runs the company behind Grok and one of the largest AI training operations anywhere. On September 25, he said another 220,000 Nvidia GB300 chips would come online at Colossus 2 within a week, with more expected in November and December.
“I think it is worth highlighting the positive benefits of A.I. … S.I., pardon me.”
“Thank you.”@elonmusk catches his own slip after calling the technology “A.I.” while speaking alongside President Trump and other tech leaders, quickly correcting himself to “super… pic.twitter.com/fH7CFileNb
— Fox News (@FoxNews) September 29, 2026
SpaceX confirms third massive compute deal at Colossus data center
Musk also used the trip to restate his energy ambitions. “SpaceX is aiming together with Tesla to do 200 gigawatts of solar production per year,” he said at an event in Washington. It is the same combined target he laid out that feeds directly into Terafab, the Tesla and SpaceX chip venture that will need enormous amounts of power.
The showing between Musk and Trump has come a long way, since the two had the very public split in mid 2025 after Musk opposed the “Big Beautiful Bill” and left DOGE. They reconciled at Charlie Kirk’s memorial that September, and Trump later called their relationship “good”. Since then, Musk has joined Trump’s China delegation in May and attended last week’s White House state dinner for Chinese President Xi Jinping.
For Tesla, that access to government official could pay dividends. As Teslarati noted in January, federal autonomy rules, NHTSA oversight and a single national standard for driverless vehicles all run through an administration Musk can more easily reach directly as Tesla works to scale Robotaxi and Cybercab beyond Texas.
Elon Musk weather update tips Tesla Roadster speculation into Plaid Mode
Tesla snags $30B in fresh credit lines for expanding its biggest projects
