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Tesla “Battery Day” event date is looking like April 2020, says Elon Musk
Tesla CEO Elon Musk said the company is preparing to host a Battery Day for shareholders sometime after the first quarter, possibly in April. The announcement came during the earnings call following Tesla’s release of its Q4 2019 Update Letter.
Responding to a question from a participating investor about where Tesla stands in growing its battery capacity, Musk said that the company has already demonstrated massive improvement in growing the capacity of the cells, modules, and batteries it uses for its all-electric vehicles.
The CEO attributed part of the improvements to Tesla’s relationships with various battery partners, such as Panasonic, which is Tesla’s in-house supplier of lithium-ion batteries at Giga Nevada. Tesla also teamed up with other partners such as LG and CATL to produce battery packs for its cars produced in China. Aside from that, Musk declined to provide additional details on future plans for improving its battery technology, leaving investors to look forward to the upcoming Battery Day event later this year.
“We have a lot more to talk about this in detail in Battery Day probably April. We have a very compelling strategy. I mean, we are super deep in cell. Super deep. Cell through battery,” he said.
Tesla’s efforts to upgrade its batteries include the acquisition of California-based energy storage firm Maxwell Technologies, which was completed in May last year. Tesla’s interest in Maxwell primarily lies in the latter’s innovations in ultracapacitors and dry electrode technologies, which could potentially improve the company’s batteries.
Prior to the acquisition, Tesla also submitted a patent for an idea to use electrolyte additives to improve the performance and lengthen the lifespan of lithium-ion cells. The patent, titled “Dioxazolones and Nitrile Sulfites as Electrolyte Additives for Lithium-ion Batteries,” provided details on how Tesla can significantly increase the lifespan and performance of its batteries by adding electrolyte additives such as lithium salt. Tesla also submitted another patent for using cold plates and heat pipes to reduce heat generated by the battery, thereby increasing the longevity of its energy storage systems.
The latest developments appear to be moving Tesla toward the completion of a 1-million mile battery. In April last year, Musk said that Tesla owners will soon be able to drive their cars for up to 1 million miles over the lifespan of their vehicles. This is equivalent to 20 years if the cells are used for energy storage systems. Tesla lead researcher Jeff Dahn and a team from the Dalhousie University physics and atmospheric science department have also developed pouch cells that can last 1 million miles or 20 years in a grid storage system.
Tesla’s huge lead in the electric vehicle market is due in part to its constant efforts to improve its battery technology. In fact, its batteries have improved so much over the years that the Model S is nearing a range of 400 miles. The published range for the luxury sedan is 373 miles, but Musk said during the earnings call that the actual range is somewhere in the 380s.
“S and X actually have more range than we are currently stating on the website. We just haven’t gotten around to updating the EPA […] number, but the actual range of the Model S and X are above what the website says they are,” he said. “Somewhere in the 380s, something like that.”
He also added that the 18650 lithium-ion cells that power the Model S and X have largely improved over the years, adding that further developments could raise the range of the Model S to 400 miles.
“I think we’re pretty happy with the energy content of the cell and the improvements in the efficiency of the vehicle,” he said. “We’re rapidly approaching a 400-mile range for the Model S, for example.”
Battery Day is expected to be similar to Autonomy Day, which was held in April last year. The event, which was attended by investors and also available via livestream, was a full three-hour technical discussion of Tesla’s work on autonomous driving technology and how the company plans to achieve its goal of delivering fully self-driving cars.
A Tesla Semi caught fire in Hayward, California, which caused both directions of traffic to shut down for hours before being completely reopened early on Wednesday, the California Highway Patrol said.
The fire occurred just after 5:30 local time in Hayward on Tuesday, as the Semi caught fire in the southbound lanes of I-880 before CHP officials made the decision to shut down both lanes of traffic due to potential risks from hazardous chemical smoke.
There were no injuries reported.
🚨 A Tesla Semi reportedly caught fire, with California Highway Patrol confirming. The Semi was on I-880 SB
An estimated 5,000 to 7,000 semi-truck and large commercial vehicle fires occur on U.S. roadways every year
— TESLARATI (@Teslarati) October 28, 2026
The cause of the fire is currently unknown, as neither Tesla nor the CHP have not determined a cause.
However, some images taken before the Semi was completely destroyed by the fire seem to indicate this might have been an older unit, as it appears to be one of the designs that Tesla shipped as part of its pilot program, before revising it and starting mass production just a month ago.
@Tslachan From on of the videos looks like it’s an old Semi (not the refresh version that recently started production) https://t.co/KzwmR2kXow
— Area Under The Curve 🎗️ (@AreaUnderCurve) October 28, 2026
At the time of publication, CHP had not returned our request for a comment for additional details, including the Semi involved and any potential collaboration on an investigation between the CHP and Tesla. We will update this story when we hear back from them.
The southbound lanes were reopened at 3:30 a.m. on Wednesday, with the northbound lanes opening last night a few hours after the fire began. The CHP did state that the lithium batteries were “incredibly difficult to extinguish,” according to NBC Bay Area.
The truck’s driver said that the Semi caught fire, but he did not have an explanation.
An estimated 5,000 to 7,000 semi-truck and large commercial vehicle fires occur on U.S. roadways every year.
Tesla’s launch of the “Emergency Drive Away” function a few months back offered owners a safe option to evacuate an area if they were in reasonable danger. The function finally got its first use in the real world, but it appears it was by mistake.
A video shared by u/Joshalander in the r/TeslaLounge subreddit recorded the instance from his vehicle and said the incident took place in Austin this past weekend during the city’s F1 Race.
“Was charging around 6 AM this past Sunday in Austin before heading to the F1 race and heard a pop. Looked over and saw the new emergency drive-away feature in action. Genuinely felt bad for the dude when he got out and realized what happened, since he looked exhausted and only seemed to half-read the prompts.”
🚨 Here’s the first look at Tesla’s Emergency Drive Away function in action:
Apparently this driver accidentally enabled it and drove forward; you can see the Supercharger pull with the car.
Tesla said previously this would cost up to $25k if not used properly. https://t.co/B4qQRrsO6B
— TESLARATI (@Teslarati) October 28, 2026
Emergency Drive Away unlatches the Supercharger connector from the vehicle, but still causes damage to both the car and the Supercharger. Tesla has said that it will cost up to $25,000 in repairs to have everything fixed back to normal.
Additionally, the company said that if it were not used in an emergency situation, the driver of the vehicle who activated the Emergency Drive Away feature would be responsible for all repair costs.
Tesla constitutes the following situations as reasonable justifications for activating the feature:
- You face an immediate threat to your life or personal safety.
- You must leave the area immediately.
- Exiting the vehicle is unsafe.
- Unplugging the charge connector would unreasonably delay your departure or expose you to a risk to your personal safety.
After using the feature, Tesla requires the driver to schedule Service so the car can be inspected.
News
Tesla’s Cybercab battery design could make robotaxis even cheaper
Tesla built the Cybercab’s battery pack with spare room for a future switch to LFP.
Tesla built the Cybercab’s battery pack with empty space inside it on purpose, and the reason points to a cheaper robotaxi down the road.
Robert Sumpf, Tesla’s director of mechanical design engineering for battery modules and packs, said the extra room beside and beneath the Cybercab’s modules was left there so the company can move to lithium iron phosphate cells later. “So, we protected this pack to go to an even lower energy dense chemistry as we scale and need to bring LFP into the platform,” Sumpf said in a Cybercab deep dive with Munro Live.
The Cybercab runs on Tesla’s own 4680 cells with a nickel chemistry today. LFP cells store less energy for their size, so a straight swap would cut range. The reserved space lets Tesla add more LFP cells to make up the difference. In return, Tesla would get cells that cost less, run cooler and survive more charge cycles. LFP became the most used EV battery chemistry in the world last year.
Not all of that room was planned for a chemistry change. Lars Moravy, Tesla’s Vice President of Vehicle Engineering, said part of it exists because “we didn’t need as many batteries as we thought we did.” Tesla told Sandy Munro in early 2025 that it was targeting a Cybercab pack under 50 kWh with close to 300 miles of range.
The pack also breaks from the structural design Tesla used in some Model Y and Cybertruck builds. Instead of potting hundreds of cells into one block, the Cybercab uses four separate, individually sealed modules, so a bad module can be replaced without scrapping the whole pack. Sumpf was blunt about the older approach, giving the Model Y structural battery “a grade D” because it was hard to build and nearly impossible to repair. He estimated a fully structural pack gains about 10% more cell volume, but said “the issue is the service cost.”
That cost matters more for a car that rarely sits parked. Cybercab chief engineer Eric Earley said replacing an entire pack “before half a million miles is a killer on cost,” which is why remanufacturing and serviceability were built into the design from the start.
The same Munro Live tour produced Moravy’s admission that the Cybercab line at Giga Texas is now outpacing Robotaxi deployments, along with a look at the robotaxi’s unorthodox paint process. Tesla is aiming to deliver the first Cybercabs to outside customers by the end of 2026, though Elon Musk has said the vast majority will stay owned by Tesla and run as a transport service.
Sumpf did not give a date for an LFP version, name a cell supplier or say how a chemistry change would affect range. For now, the 4680 cars keep piling up: Texas DMV records from Tuesday list 544 Cybercabs authorized for Tesla’s Robotaxi fleet, more than the 507 Model Ys on the same roster for the first time.
Tesla Semi catches fire in California: what we know
Tesla’s ‘Emergency Drive Away’ function gets its first use in the real world
