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Tesla ‘Roadrunner’ cell leak hints that Battery Day will be more insane than expected
Tesla’s Battery Day has been hyped so much that the event will have to include something truly amazing to live up to its expectations. In the lead up to the highly-anticipated event, a leaked image featuring what is supposedly a cell from Tesla’s “Roadrunner” line has emerged. And if the leak proves legitimate, it would appear that Battery Day will not only meet expectations — it will be even more insane than expected.
The leaked image, which was initially published in a report on Electrek, featured a massive battery cell that was supposedly a product of the Roadrunner line. The publication noted that the image was sent through an anonymous source and confirmed by another independent source. From the get-go, it is evident that the cell is massive, closer in size to a supercapacitor than a traditional battery cell. Initial observations by battery enthusiasts online also point to some radical improvements that such a cell design would bring.
While Electrek’s sources have mentioned that the Roadrunner cell will feature roughly double the diameter of the 2170 cells that the electric car maker currently uses in the Model 3 and Model Y, Tesla enthusiast @_BRCooper, who is familiar with battery tech, has observed that one of the leaked images had the number “054” printed on its side. If this number represents the cell’s diameter, it would point to Tesla’s Roadrunner cells adopting a 54×98 form factor, which has 10x the volume of a 2170 cell.
As noted by Jordan Giesige of The Limiting Factor channel on YouTube, adopting a 54×98 form factor for its next-generation cells has numerous implications for the entire battery manufacturing process and the performance of Tesla’s vehicles as a whole. With the larger cells, Tesla could produce battery packs that have an order of magnitude fewer cells than before. This would result in the company only using 1/10 the number of rolls, cans, electrolyte fills, and welds compared to its current operations. Such a strategy opens the doors to massive cost reductions that could help bring down the prices of electric cars to a notable degree.
But regardless of its actual size, the design of the Roadrunner cell appears to be optimized and designed for a cell-to-pack drop-in setup. Interestingly enough, the leaked image of the Roadrunner cell seems to have a tabless electrode design, which Elon Musk has dubbed is “way more important than it sounds” last year. Provided that the Roadrunner cells are indeed inspired by Tesla’s tabless electrode patent, the new form factor could pave the way to more performance and further reductions in production costs.
What’s even more notable is that these improvements become possible with just the Roadrunner cell’s new form factor and design. Giesige, for his part, has noted that with the Roadrunner cell’s design and potential 54×98 form factor alone, Tesla may be able to close in on 300 wh/kg before making any significant changes to its battery chemistry. Elon Musk actually mentioned a 30-40% improvement from 250 wh/kg back in 2018, which translates to an improvement to 325-350 wh/kg. Musk’s prediction was considered fantastical by critics then, but as Battery Day approaches and leaks start to emerge about the event, it is starting to look more and more likely that 325-350 wh/kg is feasible.
Watch a feature on the Roadrunner battery cell leak in the video below.
In a pointed message on X, Elon Musk warned that firms maintaining significant short positions in SpaceX over time face “very low” survival probability.
The statement comes amid post-IPO volatility for the rocket company, now trading under the ticker $SPCX.
The survival probability of firms who maintain a significant short position in SpaceX over time is very low
— Elon Musk (@elonmusk) July 17, 2026
Five weeks after what was described as the largest IPO in history, the stock had fallen roughly 30% from its peak above $2.6 trillion, briefly surpassing Microsoft and Amazon in market value. Short sellers celebrated gains of about $8.7 billion, but Musk’s reply underscores his long-term conviction.
The warning directly echoes a detailed bullish analysis arguing that Starship’s cost reductions could unlock a multi-trillion-dollar space economy. Projects ranging from solar power beamed from orbit and asteroid mining to orbital data centers and Mars terraforming were projected to create over $100 trillion in new market capitalization.
In this vision, SpaceX acts as the essential infrastructure provider, akin to AWS for cloud computing, capturing monopoly-like revenues from launches, crew transport, and data traffic across a rapidly expanding frontier.
This is far from the first time Musk has targeted short sellers. With Tesla, he has repeatedly framed persistent bears as destined for major losses. In July 2024, Musk declared that once Tesla achieves full autonomy and volume production of Optimus robots, “anyone still holding a short position will be obliterated. Even Gates,” referencing Microsoft co-founder Bill Gates’ reported short bets.
Elon Musk reveals what Tesla stock surge could do to Bill Gates
Earlier, in 2018, he taunted shorts that they had “about three weeks before their short position explodes,” a remark followed by sharp stock gains. Musk has also called short selling “value destroying” and once suggested it “should be illegal,” viewing it as betting against innovation and progress.
Critics often dismiss Musk’s optimism as hype, especially when near-term metrics like quarterly deliveries or stock fluctuations disappoint.
Yet his pattern remains consistent: framing short positions against his companies as fundamentally misjudging exponential technological leaps. For SpaceX shorts, the message is clear: betting against multi-planetary ambitions and the infrastructure monopoly they enable carries existential risk for the firms involved.
As Musk and supporters see it, the space economy’s upside dwarfs Earth-bound valuation models, making today’s dips temporary in a decades-long ascent.
Tesla has evidently revealed which of its vehicle models will be the first to receive Starlink integration: the Cybercab.
Tesla’s Santana Row showroom now has a full-fledged display of the Cybercab, with an extensive bit of information hung around an exhibit that seems to reveal the vehicle’s newest feature: an integrated Starlink antenna that will enable secure and reliable internet access during trips.
Credit: @Starscream_SJC | X
Cybercab is geared toward autonomous ride-hailing for one or two passengers. The production units rolling off the lines at Gigafactory Texas are built without steering wheels or pedals, meaning when public rides begin, passengers will not need to interact with a human being or control the vehicle in any way outside of what appears on the center screen for their entertainment during the ride.
Tesla Santana Row will be reopening tomorrow with a full focus on self-driving. Everything in the showroom is about Robotaxi and Cybercab with stats and information about the technology. The Cybercab on display is the production model. pic.twitter.com/yIUYdOGFOp
— Shaun Cassidy (@Starscream_SJC) July 20, 2026
Along the display, Tesla wrote this message about Cybercab:
“Cybercab is built for autonomy. It has no steering wheel, no side mirrors, and no pedals. It goes where you tell it to go and how you want it to, so you can relax along the way. It is hyper aware and responsive to your surroundings, monitoring other drivers, responding to emergency vehicles, utilizing its expertise in the rarest scenarios to help keep you safe.”
Tesla has been teasing a potential Starlink integration for quite some time now. In December, the company hinted at potential Starlink internet terminal integration within its vehicles in a patent that described a vehicle roof assembly with integrated radio frequency (RF) transparency.
The company wrote in its patent application that a new roof design built with materials that differ from the standard metallic or glass elements used in today’s cars would allow it to integrate modern vehicular technologies, in particular, ones that require radio frequency transmission and reception.
Tesla suggested high-strength polymer blends, like Polycarbonate, Acrylonitrile Butadiene Styrene, or Acrylonitrile Styrene Acrylate.
This is the first time we’ve seen Tesla officially confirm the Starlink integration into the Cybercab. It’s not much of a surprise considering the company’s intention behind the Cybercab, which is to make travel autonomous.
Productivity will now be at a maximum during a work-related commute, while the center screen could be utilized for Netflix or potentially even live TV for those who are heading to dinner or to a fun activity.
SpaceX has updated its target for the thirteenth integrated flight test of Starship, aiming for as early as Thursday, July 23. The 90-minute launch window opens at 5:45 p.m. CT from the company’s Starbase facility in South Texas.
The target flight was initially rescheduled for today, but SpaceX pushed it back again.
This latest adjustment follows an aborted attempt earlier in the week and reflects the iterative, rapid-development approach that has defined the Starship program. With the vehicle already stacked and ground teams making final preparations, the mission represents another step toward proving the full reusability of the world’s most powerful rocket system.
Now targeting to launch Starship’s thirteenth flight test as early as Thursday, July 23 → https://t.co/Rp7VwBzpWx pic.twitter.com/Y0YNzfc5zk
— SpaceX (@SpaceX) July 19, 2026
The original launch attempt on July 16 was scrubbed at T-0 when several Raptor engines on the Super Heavy booster failed to ignite properly. The automatic abort system triggered just as the engines began their startup sequence, preventing liftoff.
SpaceX CEO Elon Musk confirmed that some engines did not start as expected, prompting the decision to replace two Raptors on Booster 20 to ensure reliability. The issue occurred despite a successful full-duration static fire earlier, highlighting the complexities of coordinating 33 engines under flight conditions.
This cautious approach underscores SpaceX’s commitment to safety amid an aggressive test cadence.
Flight 13 builds directly on the lessons from Flight 12 in May 2026. The Super Heavy booster’s primary goals include a successful liftoff, ascent, stage separation, boostback burn, and controlled splashdown in the Gulf of America.
Hardware and software modifications address the off-nominal flip and boostback burn problems from the prior flight, where propellant slosh and engine relight issues led to an uncontrolled impact.
For the Starship upper stage, objectives include deploying 20 operational Starlink V3 satellites, the first real payload of this type, performing a single Raptor engine relight in space, and executing a controlled entry, descent, and splashdown in the Indian Ocean. Propulsion upgrades aim to improve engine-out capability after one vacuum Raptor was lost on Flight 12.
Additional test elements focus on heat shield performance. Six satellites carry cameras to image the tiles during flight, while white-painted tiles and upgraded attachments on flaps and the aft skirt will gather data for future reusability.
The FAA completed its mishap investigation into Flight 12 earlier this month, clearing the regulatory path.
This suborbital mission, the second with V3 vehicles, advances Starship toward operational missions, including potential crewed flights and support for NASA’s Artemis program. Success would mark significant progress in rapid reusability and satellite deployment from the massive system.
Elon Musk sends first warning to SpaceX short sellers
Tesla reveals first vehicle model to receive Starlink integration
