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Tesla’s ‘Roadrunner’ facility gets a neighbor working on tech beyond the million-mile battery
As the wait for Tesla’s Battery Day continues, more and more speculations are abounding about what the electric car maker might reveal during the highly-anticipated event. Elon Musk has stated that Battery Day’s announcements will be mind-blowing, and based on apparent clues recently observed by the Tesla community, it appears that the CEO may be right on the money.
Recent reports have indicated that Amprius, a battery company currently working on silicon nanowire tech, recently relocated its headquarters to a site that’s just a few hundred feet away from Tesla’s Roadrunner battery facility in Kato Road, Fremont. Considering the firm’s focus, its new headquarters’ rather convenient location, and Elon Musk’s previous references to the use of silicon in batteries, there seems to be a fair chance that Amprius’ move to Fremont may be more than a coincidence.
Amprius notes that it is working on creating silicon nanowires for battery anodes that dramatically improve battery weight and density. The company’s website notes that silicon generally has about 10x the capacity of graphite (carbon), but it has a big drawback in the way that it swells when it’s charged, causing the silicon to fracture. To address this, Amprius utilizes silicon nanowires, which keeps the silicon from fracturing and breaking apart even when it swells.
As noted by EV enthusiast and YouTube host Driving Delta, Elon Musk himself appears to be teasing the use of advanced silicon tech on Twitter last month. In one of his posts, Musk shared some lyrics of the song “Lithium” by Nirvana, whose refrain includes sections that state “I’m not gonna crack.” Granted, Musk may simply be trolling the Tesla community with his posts, but it should be noted that he also talked about the increasing use of silicon anodes five years ago.
“We’re shifting the cell chemistry for the upgrade battery pack to partially use silicon in the anode. This is just a sort of baby step in the direction of using silicon in the anode. We’re still primarily using synthetic graphite, but over time, we’ll be using increasing amounts of silicon in the anode,” Musk noted during a 2015 conference call.
As noted by Amprius’ on its website, the use of 100% silicon paves the way for batteries with the highest energy density, perhaps even at the 500 Wh/kg level. That’s enough to start exploring electric VTOL projects, a topic that Elon Musk has admitted is something that truly interests him. That being said, Professor in Energy Materials and Technologies Ying Shirley Meng, who has made significant contributions to Maxwell Technologies’ battery tech herself, believes that challenges still remain in the use of silicon nanowires.
“We should pay attention to the cost per kg. Even (if) those nanowires work (which I doubt), to produce consistent quality in metric ton scale at 10$ per kg it will be sci-fi for now,” she noted.
Elon Musk, for his part, recently stated that the technology that could allow 400 Wh/kg with a high life cycle and volume production is not too far away. Musk gave a rough timeframe for the technology, stating that such milestones could be achieved in about three to four years.
Tesla’s Battery Day event is expected to introduce the company’s next-generation lithium-ion cells, though speculations suggest that these batteries — which are expected to last a million miles — are based largely on Maxwell Technologies’ dry electrode tech. Maxwell itself has previously noted that it could offer batteries with 300 Wh/kg while stating that it had also identified a path to 500 Wh/kg. With this in mind, it appears that Tesla may already be setting the stage for cells that will likely go even beyond the million-mile battery.
Granted, Amprius’ move to Fremont may be unconnected to Tesla. That being said, the two companies’ goals to align with each other, and Elon Musk’s own references to the use of silicon suggests that Tesla will likely get a lot of value from Amprius’ tech. If speculations prove true, the path to batteries that go even further than the million-mile mark may be feasible in the near future. Such innovations are key to Tesla’s goal of accelerating the transition to sustainable energy, after all.
Watch these recent takes on the Amprius rumors in the videos below.
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Tesla hints at Starlink integration with recent patent
“By employing polymer blends, some examples enable RF transmission from all the modules to satellites and other communication devices both inside and outside the vehicle.”
Tesla hinted at a potential Starlink internet terminal integration within its vehicles in a recent patent, which describes a vehicle roof assembly with integrated radio frequency (RF) transparency.
The patent, which is Pub. No U.S. 2025/0368267 describes a new vehicle roof that is made of RF-transparent polymer materials, allowing and “facilitating clear communication with external devices and satellites.”
Tesla believes that a new vehicle roof design, comprised of different materials than the standard metallic or glass elements used in cars today, would allow the company to integrate modern vehicular technologies, “particularly those requiring radio frequency transmission and reception.
Tesla has recently filed a US patent application on integrating RF transparent materials into the roof structure.
“facilitating clear communication with external devices and satellites”
Tesla fleet is getting @Starlink connectivity integration soon. LFG @Tesla @elonmusk… pic.twitter.com/bLa8YtPLd1
— Chansoo Byeon (@Chansoo) December 9, 2025
Instead of glass or metallic materials, Tesla says vehicles may benefit from high-strength polymer blends, such as Polycarbonate, Acrylonitrile Butadiene Styrene, or Acrylonitrile Styrene Acrylate.
These materials still provide ideal strength metrics for crashworthiness, stiffness for noise, vibration, and harshness control, and are compliant with head impact regulations.
They would also enable better performance with modern technologies, like internet terminals, which need an uninterrupted signal to satellites for maximum reception. Tesla writes in the patent:
“By employing polymer blends, some examples enable RF transmission from all the modules to satellites and other communication devices both inside and outside the vehicle.”
One of the challenges Tesla seems to be aware of with this type of roof design is the fact that it will still have to enable safety and keep that at the forefront of the design. As you can see in the illustration above, Tesla plans to use four layers to increase safety and rigidity, while also combating noise and vibration.
It notes in the patent that disclosed examples still meet the safety requirements outlined in the Federal Motor Vehicle Safety Standards (FMVSS).
Starlink integrated directly into Tesla vehicles would be a considerable advantage for owners. It would come with a handful of distinct advantages.
Initially, the inclusion of Starlink would completely eliminate cellular dead zones, something that is an issue, especially in rural areas. Starlink would provide connectivity in these remote regions and would ensure uninterrupted service during road trips and off-grid adventures.
It could also be a critical addition for Robotaxi, as it is crucial to have solid and reliable connectivity for remote monitoring and fleet management.
Starlink’s growing constellation, thanks to SpaceX’s routine and frequent launch schedule, will provide secure, stable, and reliable internet connectivity for Tesla vehicles.
Although many owners have already mounted Starlink Mini dishes under their glass roofs for a similar experience, it may be integrated directly into Teslas in the coming years, either as an upgrade or a standard feature.
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Tesla supplements Holiday Update by sneaking in new Full Self-Driving version
It seems Tesla was waiting for the Hardware 4 rollout, as it wanted to also deploy a new Full Self-Driving version to those owners, as it appeared in the release notes for the Holiday Update last night.
Tesla has surprised some owners by sneaking in a new Full Self-Driving version with the wide release of the Holiday Update, which started rolling out to Hardware 4 owners on Friday night.
Tesla has issued a controlled and very slow release pattern with the Holiday Update, which rolls out with Software Version 2025.44.25.5.
For the past two weeks, as it has rolled out to Hardware 3 and older Tesla owners, the company has kept its deployment of the new Software Version relatively controlled.
It seems Tesla was waiting for the Hardware 4 rollout, as it wanted to also deploy a new Full Self-Driving version to those owners, as it appeared in the release notes for the Holiday Update last night.
Tesla Full Self-Driving v14.2.1.25 made its first appearance last night to Hardware 4 owners who are members of the Early Access Program (EAP). It appears to be a slight refinement from FSD v14.2.1, which has been out for a couple of weeks.
Tesla v2025.44.25.5 Holiday update incoming
Also Full Self-Driving v14.2.1.25!!! pic.twitter.com/74D7S0UGXz
— TESLARATI (@Teslarati) December 13, 2025
Many owners welcome the new FSD version, us included, because we’ve been less than impressed with v14.2.1. We have experienced some minor regressions with v14.2.1, especially with Speed Limit recognition, Speed Profile tinkering, and parking performance.
As it stands, Full Self-Driving is still particularly impressive, but Tesla is evidently having an issue with some of the adjustments, as it is still refining some of the performance aspects of the suite. This is expected and normal with some updates, as not all of them are an improvement in all areas; we routinely see some things backtrack every once in a while.
This new FSD version is likely to take care of those things, but it also includes all of the awesome Holiday Update features, which include:
- Grok with Navigation Commands (Beta) – Grok will now add and edit destinations.
- Tesla Photobooth – Take pictures inside your car using the cabin-facing camera
- Dog Mode Live Activity – Check on your four-legged friend on your phone through periodic snapshots taken of the cabin
- Dashcam Viewer Update – Includes new metrics, like steering wheel angle, speed, and more
- Santa Mode – New graphics, trees, and a lock chime
- Light Show Update – Addition of Jingle Rush light show
- Custom Wraps and License Plates – Colorizer now allows you to customize your vehicle even further, with custom patterns, license plates, and tint
- Navigation Improvements – Easier layout and setup
- Supercharger Site Map – Starting at 18 pilot locations, a 3D view of the Supercharger you’re visiting will be available
- Automatic Carpool Lane Routing – Navigation will utilize carpool lanes if enabled
- Phone Left Behind Chime – Your car will now tell you if you left a phone inside
- Charge Limit Per Location – Set a charge limit for each location
- ISS Docking Simulator – New game
- Additional Improvements – Turn off wireless charging pad, Spotify improvements, Rainbow Rave Cave, Lock Sound TRON addition
Tesla also added two other things that were undocumented, like Charging Passport and information on USB drive storage to help with Dashcam.
Tesla is updating Cybertruck owners on its timeline of a massive feature that has yet to ship: Powershare with Powerwall.
Powershare is a bidirectional charging feature exclusive to Cybertruck, which allows the vehicle’s battery to act as a portable power source for homes, appliances, tools, other EVs, and more. It was announced in late 2023 as part of Tesla’s push into vehicle-to-everything energy sharing, and acting as a giant portable charger is the main advantage, as it can provide backup power during outages.
Cybertruck’s Powershare system supports both vehicle-to-load (V2L) and vehicle-to-home (V2H), making it flexible and well-rounded for a variety of applications.
However, even though the feature was promised with Cybertruck, it has yet to be shipped to vehicles. Tesla communicated with owners through email recently regarding Powershare with Powerwall, which essentially has the pickup act as an extended battery.
Powerwall discharge would be prioritized before tapping into the truck’s larger pack.
However, Tesla is still working on getting the feature out to owners, an email said:
“We’re writing to let you know that the Powershare with Powerwall feature is still in development and is now scheduled for release in mid-2026.
This new release date gives us additional time to design and test this feature, ensuring its ability to communicate and optimize energy sharing between your vehicle and many configurations and generations of Powerwall. We are also using this time to develop additional Powershare features that will help us continue to accelerate the world’s transition to sustainable energy.”
Owners have expressed some real disappointment in Tesla’s continuous delays in releasing the feature, as it was expected to be released by late 2024, but now has been pushed back several times to mid-2026, according to the email.
Foundation Series Cybertruck buyers paid extra, expecting the feature to be rolled out with their vehicle upon pickup.
Cybertruck’s Lead Engineer, Wes Morrill, even commented on the holdup:
As a Cybertruck owner who also has Powerwall, I empathize with the disappointed comments.
To their credit, the team has delivered powershare functionality to Cybertruck customers who otherwise have no backup with development of the powershare gateway. As well as those with solar…
— Wes (@wmorrill3) December 12, 2025
He said that “it turned out to be much harder than anticipated to make powershare work seamlessly with existing Powerwalls through existing wall connectors. Two grid-forming devices need to negotiate who will form and who will follow, depending on the state of charge of each, and they need to do this without a network and through multiple generations of hardware, and test and validate this process through rigorous certifications to ensure grid safety.”
It’s nice to see the transparency, but it is justified for some Cybertruck owners to feel like they’ve been bait-and-switched.
Tesla hints at Starlink integration with recent patent
Tesla supplements Holiday Update by sneaking in new Full Self-Driving version
