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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.
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On Friday, Tesla launched the Outlet Adapter that enabled Vehicle-to-Load (V2L) energy transfer, meaning owners could essentially utilize their cars as a power source for things like laptops, electric grills, or string lights.
However, even owners of some of the newest builds of the Model Y are finding out that their cars are not compatible with the new $80 accessory, stirring up a new complaint among members of the community.
Tesla launches V2L Outlet Adapter for Premium Model Y in the U.S.
Upon the release of the Outlet Adapter on Friday, I signed into my Tesla account to order the accessory. However, I was met with the dreaded “This product is not compatible with your 2026 Model Y” message at the bottom of the screen.
Some said their accounts also displayed the same message, but they ordered anyway. However, they might be surprised to find that this is no mistake; some of the newest Model Ys do not have the appropriate Power Conversion System (PCS). Mine, which was ordered on this day last year and delivered on August 31, has the old 48A, single-phase PCS.
Vehicles with the new, two-piece PCS are able to utilize V2L features on their cars:
🚨 Looks like you can hit the Parts Catalog and enter your VIN and check to see if your Model Y will be able to use the adapter for V2L.https://t.co/QA9zRk7n2k
h/t to @SawyerMerritt for finding this out.
I am sad but this isn’t a huge loss. https://t.co/AYpI12QVV9 pic.twitter.com/LRFSrtRywo
— TESLARATI (@Teslarati) August 16, 2026
Obviously, it’s disappointing. Many owners have taken delivery this year and still can not utilize the Outlet Adapter because their cars feature the old PCS:
Took delivery in February of 2026. I have the older one, so not going to work for me pic.twitter.com/RcOVq8gvvT
— Russell (@QuietTesla) August 16, 2026
It looks like if you have one of these older PCS units, you can upgrade, but the parts alone are $1,750, and that’s before Tesla adds labor for installing. It is honestly more logical to get some kind of portable power supply or power station at that point.
It is great that Tesla has enabled V2L for Model Y vehicles, but it is also unfortunate that vehicles that are less than one year old are not able to take advantage of this awesome new feature.
With that being said, it truly is a first-world problem; can you really complain when Full Self-Driving is available, maintenance is incredibly inexpensive, and the car has been so good through a year of ownership?
Tesla has launched a new Vehicle-to-Load (V2L) Outlet Adapter for Premium Model Y vehicles in the United States, meaning you can now power devices like laptops or light strings with your vehicle’s battery.
It appears the capability will be available for any Model Y Premium trim, including those that were purchased prior to the Adapter being launched. It will also only impact Juniper Model Y vehicles, so the first-gen owners will unfortunately not have access to this capability.
If your Model Y was purchased before Tesla renamed the trim levels to “Premium” and “Standard,” it does not seem to be compatible. My Model Y is technically a Premium build, as it is the Long Range All-Wheel-Drive. However, Tesla says it is not compatible with my vehicle.
🚨 Tesla has launched the Outlet Adapter for Model Y Premium in the U.S., enabling V2L capability for all Premium trims (that’s what it appears to be as it is available for purchase with all Premium trims)
It’s available for $80. 2.4kW max power and rated for 120v, 20A pic.twitter.com/lDxlVIk5s8
— TESLARATI (@Teslarati) August 14, 2026
For $80, you can now utilize your car as a portable charger for small appliances or devices. This is perfect for things like tailgates, concerts, or camping, as you can now plug in devices that you might use. Those string lights for camping? That laptop for the other games that are on at the tailgate?
They’ll both utilize energy from your Tesla’s battery to be powered. This is the first time Tesla has expanded the capability to vehicles outside of the Model Y Performance and Cybertruck. However, this feature has been highly requested by owners for an extended period of time.
Tesla launched the Outlet Adapter in China last year:
Tesla China rolls out Model Y L V2L adapter, and it’s free for early owners
You will need the Mobile Connector to operate the Outlet Adapter: the Outlet Adapter will plug into the main housing of the Mobile Connector, where the appropriate adapter to charge your vehicle will plug in.
It is rated for 120 volts and 20 amps, and has a max power rating of 2.4kW.
You can buy it here from Tesla for $80.
Tesla is nearing its long-awaited unveiling of the all-electric Tesla Roadster, a new report from The Information claims, as the company has said several times this year that the event would take place “soon.”
Now, it appears there is movement on Tesla’s end regarding when it will happen.
The report says that Tesla will unveil the Roadster as soon as this month with a SpaceX version that will utilize cold-gas thrusters to help the vehicle float for a short period of time. This is something CEO Elon Musk has talked about with the Roadster for years.
🚨 The Information is reporting this morning that Tesla is ready to unveil the “flying” Roadster as soon as this month
It’s almost here, folks. pic.twitter.com/IdL4atsucQ
— TESLARATI (@Teslarati) August 14, 2026
Additionally, due to the delays, Tesla explored “a variety of designs” for the Roadster, potentially planning to abandon the design it showed off for the first time in 2017 and adopting an entirely new aesthetic.
According to The Information, Tesla considered utilizing a repurposed Model S Plaid and even wanted to upgrade the look to something like a Lamborghini Countach.
We’ve heard all of these things before, including teases about the date and how “soon” the Roadster will finally be ready to be shown off to the world (for the second time). Musk said that the event would occur in April, then May, then Chief Designer Franz von Holzhausen continued to say it would be coming “soon.”
We do expect to see the Roadster by the end of the year, and now with this new report swirling, it appears it could be sooner rather than later.
The wait has been incredibly long, but there is likely a good reason for it. Tesla’s desire to make the Roadster the craziest vehicle on the road was non-negotiable, and it likely took a lot of time and resources to develop and perfect into something that was safe and suitable for a vehicle like this.
Tesla V2L adapter for Model Y stirs up a new complaint among owners
Tesla launches V2L Outlet Adapter for Premium Model Y in the U.S.
