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Tesla can solve an annoying part of its cars’ ownership experience with Maxwell’s supercapacitors
When Tesla acquired Maxwell technologies, the electric vehicle community was appropriately excited. Maxwell, after all, works on projects such as dry battery electrode tech and supercapacitors, both of which are believed to hold a lot of potential in the emerging electric vehicle sector. But as the countdown to the highly-anticipated Battery Day draws near, speculations suggest that Tesla acquired Maxwell mainly due to the company’s dry battery electrode tech, not its supercapacitors. Yet according to Andrey Shigaev, CEO of Geyser Batteries, supercapacitors still hold some potential uses for Tesla’s electric cars.
In a brief interview with Teslarati, Shigaev, whose company is developing batteries that use aqueous (water-based) electrolytes, noted that while supercapacitors will likely not be involved in Tesla’s million-mile battery project, there are already a lot of local tasks in an electric vehicle that could benefit from the use of supercapacitors. Among these is smart air suspension, a feature that is currently used in the Model S and X and is expected for upcoming vehicles like the Cybertruck. But beyond this, the Geyser Batteries CEO mentioned that supercapacitors could also be utilized as a superior alternative to the 12V battery that Tesla uses for its vehicles today.
“The more stuff gets electrified, the more power you need to perform tasks. The most classical thing (that could benefit from supercapacitors) and the number one item for Tesla is the 12V battery. Supercapacitors can handle this task. If you have a high energy battery onboard, then this secondary circuit could be powered by a supercapacitor that is very efficient. It will even have an extremely long life cycle. Supercapacitors are lighter too, saving weight. And they tend to be smaller than a lead-acid battery,” Shigaev said.
Interestingly enough, the earliest versions of the original Tesla Roadster didn’t use a 12V battery. Instead, the company used a portion of the Roadster’s main lithium-ion battery pack to supply 12V for the vehicles’ accessories and lights. This did not prove ideal, however, and in 2010, Tesla switched to using a 12V battery for the Roadster 2.0. It should be noted that the 12V battery, which has been adopted in every vehicle since the Roadster 2.0, is used to keep systems such as emergency blinkers, airbags, seatbelt pre-tensioners, the MCU, and other functions operational even when a car’s main battery pack is compromised.
Being one of the few parts of the car that is still based on conventional automotive tech, the 12V battery in a Tesla tends to last only a few years. As noted by Tesla Tap, the 12V battery in a brand new Tesla could last about 3-4 years, but this could be reduced to as little as 1-2 years if the vehicle is driven frequently. This could cause annoyances among Tesla owners, especially since the 12V battery’s health could not be actively observed in the vehicle’s systems yet. Social media posts about 12V batteries in Teslas giving out are numerous, with some owners noting that it is the one aspect of the Tesla ownership experience that is still mildly infuriating.
With this in mind, the use of supercapacitors in place of the 12V battery could be pretty in-character for Tesla. Nevertheless, the Geyser CEO explained that using supercapacitors in place of the 12V battery would present some challenges as well. Among these is cost, since supercapacitors are notably more expensive than standard 12V lead-acid batteries. Yet despite this, the advantages they bring could justify their use, especially among flagship vehicles like the next-generation Roadster and the Plaid Model S and Model X.
“Supercapacitors have a main caveat. There are three drawbacks. First and foremost is energy density, which is ten times lower than lead-acid battery. Second is their price since currently, their price is astronomically larger. The third is discharge. If you leave it alone for almost one month, it would discharge completely. However, if you have an electric car and there’s a high energy battery in the car like a lithium-ion battery, that would be the power source for the vehicle,” Shigaev noted.
Other industry experts have suggested uses for Maxwell’s supercapacitors in Tesla’s electric cars in the past. Auto veteran and Munro & Associates Sr. Associate Mark Ellis previously noted that apart from dry electrode tech, Tesla could tap into Maxwell’s supercapacitors to improve its vehicles’ battery management systems.
“One of the issues with the battery is, when I step on the throttle hard, I’m pulling a lot of energy from the battery. And then, when I brake hard, I’m pulling a lot of energy out of the regen, but the batteries can’t take it fast enough. The batteries get really stressed when you try to pull it up too much, so if I had supercapacitors that I could use as a cushion; so when I need energy quickly, (I can) pull it from the supercapacitors and then fill the supercapacitors back up with the battery slowly; and then when I brake, I can capture more of that regen energy and do the supercapacitors faster. I think that just makes logical sense, because now all of a sudden I’ve got a sponge in front of my main energy source and I’m not stressing (the battery) so much,” Ellis said.
Tesla has reached a notable benchmark in its autonomous driving program after its Robotaxi fleet surpassed one million miles of unsupervised operation. The company made the announcement during its Cybercab event in Austin on September 3.
Tesla Vice President of AI Ashok Elluswamy told attendees he was happy to report the fleet had achieved one million miles of unsupervised Robotaxi operation as a testament to safety.
The new total marked a sharp increase from the 380,000 unsupervised miles Tesla disclosed during its second-quarter 2026 earnings update in late July.
In roughly six weeks, the company added about 620,000 miles. That acceleration followed Tesla’s decision to remove in-vehicle safety monitors from most of its operations outside the San Francisco Bay Area.
Credit: Tesla
Tesla first launched Robotaxi service in Austin in June 2025 with safety drivers present. It later began fully unsupervised rides and expanded into Dallas, Houston, Miami, Orlando, and Tampa. The San Francisco Bay Area remains the exception, where a safety monitor still rides in the vehicle under California permitting rules.
The company has not released a city-by-city breakdown of the one million unsupervised miles.
The milestone arrived as Tesla began offering public Cybercab rides in Austin. The purpose-built vehicle has no steering wheel or pedals and is designed only for autonomous ride-hailing. Production versions joined the existing fleet of modified Tesla vehicles already operating in the service.
Tesla’s unsupervised mileage is growing at a double-digit weekly rate according to earlier company comments, yet its fleet size remains modest compared with established competitors. Waymo has accumulated more than 200 million fully autonomous rider-only miles. Tesla has described its own unsupervised operations as having recorded zero notable incidents in the period leading up to the July update.
The one-million-mile figure reflects Tesla’s shift from supervised testing to broader driverless service in multiple states. It also highlights the company’s strategy of using both existing Model Y vehicles and the new Cybercab to scale its network.
Credit: Tesla
Whether the rapid recent growth continues will depend on further city expansions, regulatory approvals, and the performance of the purpose-built Cybercab in everyday paid rides. Tesla has not specified how many of the latest miles involved the new vehicle versus the rest of the fleet.
The announcement underscores Tesla’s progress toward a larger robotaxi network while illustrating the remaining gap in total autonomous experience relative to longer-operating rivals.
Tesla AI lead Ashok Elluswamy said this week that 24-hour Robotaxi service is close. Replying on X to a rider who wanted Cybercab trips all night, he wrote that the capability would arrive “next month or so” once “the next tech to merge on the v15 plan” is ready.
The comment landed on September 4, one day after Tesla opened public Cybercab rides in Austin. It is the clearest near-term timeline yet for overnight unsupervised operation. Tesla’s paid Robotaxi network currently runs from 6 a.m. to 10 p.m. seven days a week across Austin, Dallas, Houston, Miami, Orlando, and Tampa.
next month or so. the next tech to merge on the v15 plan will enable it.
— Ashok Elluswamy (@aelluswamy) September 4, 2026
That 16-hour window is shorter than the 6 a.m. to 2 a.m. schedule the company used for much of the prior year.
Elluswamy did not name the specific feature or say whether the change would apply first to purpose-built Cybercabs, the existing Model Y fleet, or both. He also offered no city-by-city rollout list. The link to Full Self-Driving v15 is nevertheless significant.
Tesla has described v15 as a step-change architecture with seven parallel improvement tracks and roughly ten times more parameters than earlier builds. Early versions of that software already operate on the Robotaxi fleet and contain about 40 percent of the planned gains.
By July 2026, the unsupervised fleet had logged more than 380,000 miles across six cities in two states with what the company called an impeccable safety record and no notable incidents caused by the vehicles themselves. Tesla has repeatedly argued that camera-based end-to-end neural networks, rather than extra sensors, are the core of the solution.
Overnight service would test that claim in lower-light conditions and would also raise vehicle utilization, a key variable for Robotaxi unit economics. The company has already begun using public Superchargers at night and is building dedicated Robotaxi charging sites.
Riders have asked why software must change if the cars already drive in the dark. The practical answer appears to be reliability and scale: Tesla has held back mass expansion until more of the v15 stack is merged, citing the need for higher confidence before putting thousands of unoccupied vehicles on streets around the clock.
If the next module arrives on the timetable Elluswamy sketched, 24-hour service could begin in October 2026 in at least some markets.
That would mark a shift from a daytime-bounded pilot to a service that can run whenever demand exists, including the late-night hours that have so far remained out of reach.
Tesla is beginning to roll out Full Self-Driving Supervised v14.3.9 with a new active safety layer that can take control even when the driver is operating the car manually.
Tesla AI said the software can activate FSD on the driver’s behalf when an imminent collision is detected and Automatic Emergency Braking may not be enough. It may also engage if the system detects heavy distraction or an accidental FSD disengagement.
FSD Supervised v14.3.9 starting to roll out shortly
This release includes a new active safety feature set: FSD Supervised can now activate on your behalf when an imminent collision is detected and Automatic Emergency Braking (AEB) may not be enough.
It may also engage if we…
— Tesla AI (@Tesla_AI) September 4, 2026
The capability is essentially Automatic Collision Evasion. However, unlike conventional AEB, which mainly applies the brakes in a straight line, this feature can use steering, braking, and acceleration together if the car calculates that stopping alone will not prevent impact and a safer path exists. The system may change lanes or move toward a shoulder when conditions allow, then continue driving after the immediate threat is handled rather than simply coming to a stop.
The intervention is meant as a last-resort safety net, not a replacement for attentive driving.
Tesla Full Self-Driving v14.3.7 early review: FSD saved me from an accident
Tesla’s own description still frames FSD as supervised assistance. Secondary reports on internal release notes say the feature can fire while the car is being driven manually if cabin-camera monitoring suggests the driver is not sufficiently attentive, such as reaching toward the back seat, or if FSD appears to have been turned off unintentionally.
After the emergency maneuver, the car is expected to alert the driver and request a return to manual control.
The safety case is straightforward. Many collisions happen in the last second because a driver is looking away, fumbles a control, or faces an obstacle that braking cannot fully solve. A system that can both recognize that AEB is insufficient and execute a coordinated evasive path can reduce those remaining high-severity events.
Re-engaging after accidental disengagement also addresses a practical failure mode: a small steering nudge that drops FSD at the worst moment. The advantage is a background safety net that uses the same vision stack already running in v14, instead of leaving the car solely to emergency braking once the driver is no longer in command.
The feature still depends on FSD being enabled and, according to reports, an active FSD purchase or subscription. It does not make the vehicle unsupervised. Drivers remain responsible, and Tesla has not published how often the system is expected to intervene or how it will handle false positives.
If the rollout is conservative and the false-alarm rate stays low, the update is a meaningful step: FSD is no longer only a feature the driver turns on. In the rare moments when disaster is already forming, it can step in.
Tesla crosses major Unsupervised Self-Driving milestone
Tesla Robotaxi will be a 24/7 service: here’s when
