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Tesla Semi battery weight criticisms are rooted in outdated ideas: EV expert

The Tesla Semi visits Yandell Truckaway. (Photo: Arash Malek)

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6 years ago

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A good number of skeptics critical of battery-electric long-haulers like the Tesla Semi typically argue that the weight of the vehicles’ batteries makes them ineffective against competitors that are powered by diesel or hydrogen. As noted by an electric vehicle veteran and expert recently, however, these ideas are rooted in outdated ideas about battery weight. And if one considers more recent battery tech, electric Class 8 trucks may not only be feasible; they may actually be closer than expected. 

In a recent piece on Bulk Distributor Magazine’s November/December 2020 issue, Auke Hoekstra, Senior Advisor for Electric Mobility at the Eindhoven University of Technology, noted that contrary to popular belief, long-haul trucks would not be the last vehicles to become battery-powered. This is in no small part due to the advancement of battery technology. Hoekstra noted that within five years, he believes that “electric trucks will become the logical choice for many bulk transporters” And within 10 years, vehicles like the Tesla Sei will likely dominate new sales. 

The stunning progression of battery technology could be seen in just how much batteries have gotten better and cheaper over the years. Hoekstra noted that myths about electric trucks being too heavy were true 20 years ago, but not today. If electric long-haulers existed 20 years ago, they would likely be powered by lead-acid batteries, and assuming a battery size of 1 MWh, such a vehicle will require a pack that will likely weigh about 25 tons. That’s more than the entire payload of the truck. This is, of course, not the case today. 

Hoekstra noted that when he wrote his first book about electric vehicles for the Dutch Ministry of Road Transport 13 years ago, lithium-ion batteries had started to emerge. Lithium-ion batteries offered reductions in weight, resulting in a 1 MWh pack weighing only about 10 tons. Today, this is even better, with modern electric cars having batteries that weigh about 5 kg per kWh or 5 tons per MWh. “I expect that with five years, that weight will be down to 3.5 tons. And it doesn’t stop there,” the EV veteran wrote. 

Class 8 trucks like the Tesla Semi, which are designed from the ground up to be electric, will likely offer even better weight advantages. Hoekstra estimated that Tesla would see further weight reductions of about 2.5 to 3 tons due to the vehicle’s all-electric platform. “The electric motor is lighter, and you can get rid of the diesel tank and exhaust treatment. Then you place the electric motors between the wheels and lose the differential, driveshaft, and a host of other components,” he wrote. 

What’s particularly interesting is that these estimates don’t even take into account the innovations that Tesla unveiled in its Battery Day event. Once Tesla’s 4680 tabless cells and structural battery packs enter the equation, the Semi becomes an even more compelling alternative to diesel-powered trucks. Hoekstra estimated that Tesla’s structural battery packs could save another ton to the Semi’s overall weight, seeing as the battery would practically displace the steel beams that give traditional Class 8 long-haulers their rigidity. With this in mind, the EV veteran noted that “battery weight will soon be a problem of the past.” 

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There are other advantages to electric trucks that were highlighted by Hoekstra in his piece, such as the cost savings that will result from the use of a fleet of electric trucks. This is something that Tesla has highlighted in the past, with CEO Elon Musk stating during the vehicle’s unveiling that the Semi will vastly undercut diesel-powered rivals when it comes to operating costs. Couple this with the low maintenance requirements of EVs, as well as the fact that batteries now last much longer, and trucks like the Tesla Semi will likely become very attractive options for operators in the very near future. 

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Simon is an experienced automotive reporter with a passion for electric cars and clean energy. Fascinated by the world envisioned by Elon Musk, he hopes to make it to Mars (at least as a tourist) someday. For stories or tips--or even to just say a simple hello--send a message to his email, simon@teslarati.com or his handle on X, @ResidentSponge.

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Elon Musk

Elon Musk and Trump are closer than ever, and Tesla could be the big winner

Elon Musk sat beside Trump as AI leaders signed a voluntary White House safety accord.

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2 hours ago

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September 29, 2026

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Elon Musk had the seat right next to President Donald Trump on Tuesday as the White House hosted the leaders of America’s biggest artificial intelligence companies for a lunch that ended with a voluntary industry accord on AI safety.

A seating chart Trump posted on Truth Social placed Musk at the president’s left in the East Room, with Nvidia CEO Jensen Huang on his right, according to an Associated Press reporter. Anthropic CEO Dario Amodei, OpenAI President Greg Brockman, Meta’s Mark Zuckerberg, Google’s Sundar Pichai, Microsoft’s Satya Nadella and Amazon founder Jeff Bezos also attended, along with Vice President JD Vance and House Speaker Mike Johnson.

After the lunch, Trump told reporters outside the West Wing that the executives had signed “The White House Accord on Superintelligence: A Joint Commitment on Frontier SI Responsibilities.” Johnson described it as a voluntary statement of principles built on “robust internal controls and layers of internal and external review,” while Zuckerberg said company boards would independently review reports from outside auditors. Trump called the document “morally binding,” said he would name a new AI czar within days, and signed an executive order formally renaming artificial intelligence “super intelligence,” CNBC reported.

Musk was not in the room for Tesla alone. Since SpaceX absorbed xAI, he runs the company behind Grok and one of the largest AI training operations anywhere. On September 25, he said another 220,000 Nvidia GB300 chips would come online at Colossus 2 within a week, with more expected in November and December.

SpaceX confirms third massive compute deal at Colossus data center

 

Musk also used the trip to restate his energy ambitions. “SpaceX is aiming together with Tesla to do 200 gigawatts of solar production per year,” he said at an event in Washington. It is the same combined target he laid out that feeds directly into Terafab, the Tesla and SpaceX chip venture that will need enormous amounts of power.

The showing between Musk and Trump has come a long way, since the two had the very public split in mid 2025 after Musk opposed the “Big Beautiful Bill” and left DOGE. They reconciled at Charlie Kirk’s memorial that September, and Trump later called their relationship “good”. Since then, Musk has joined Trump’s China delegation in May and attended last week’s White House state dinner for Chinese President Xi Jinping.

For Tesla, that access to government official could pay dividends. As Teslarati noted in January, federal autonomy rules, NHTSA oversight and a single national standard for driverless vehicles all run through an administration Musk can more easily reach directly as Tesla works to scale Robotaxi and Cybercab beyond Texas.

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Elon Musk

Tesla Roadster’s new patent preps white-knuckle speeds, keeping it grounded

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16 hours ago

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September 29, 2026

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Credit: @BLKMDL3/Twitter

Ahead of its highly anticipated unveiling, Tesla’s upcoming Roadster received a new patent that aims to keep it grounded while enabling white-knuckle speeds.

The patent, which was granted on September 29, is titled “Electric Car Fan,” bluntly stating its design but not its purpose, which is further detailed in the text of the application. Interestingly, it comes two weeks before the Roadster event, which was delayed due to unfavorable weather on Thursday, which could cause issues, as Tesla revealed the event must be held outdoors.

The purpose is to solve a problem that is relatively unique to high-performance electric cars. Instant motor torque is useless if the tires cannot plant that force, and conventional wings and underbody tunnels generate downforce only when air is already rushing past the car. At launch, in slow corners, and under hard braking from modest speed, passive aerodynamic additions contribute essentially very little to downforce.

Tesla’s filing says that its fans can produce the downforce needed, independent of vehicle velocity, then ease off so the same hardware does not pile on drag at highway speeds, an issue that can come from excessive body modifications.

The hardware outlined in the patent is a ducted-fan package that is placed into the rear of the vehicle. An underbody inlet between the rear wheels feeds a duct that rises to a wide outlet in the diffuser. In that outlet are four axial fans, which are divided by vertical strakes. They will pull air from under the floor and press the chassis onto the pavement.

The language in the patent claims it can cut drag rather than add to it while simultaneously increasing downforce.

Tesla Roadster event requires restricted airspace, and the FAA obliges

The fans run from the high-voltage battery and a vehicle control system, so output can be modulated rather than left on as a fixed penalty.

There are additional strengths that can come from this design, like extra tire load at low speed, which can contribute to even more face-melting acceleration rates, decrease stopping distance, and sharper turn-in before a wing has air to work with. Adjustable fan speed lets the car add grip only when needed, so it can be catered to the force of a turn or acceleration.

These designs were previously used, and banned, in some competitive settings. The Brabham BT46B was banned in F1 competition for using a similar fan design and being labeled as too effective.

Tesla still lists the Roadster as having a sub-two-second 0-60 MPH time and a 250-plus-MPH top speed, and there are expectations for a SpaceX cold-gas thruster package that could not only increase acceleration but potentially cause the vehicle to hover.

It is important to note that a patent is not a production part, and packaging four fans in a rear diffuser, managing noise, and potential debris are all things Tesla must consider. With that being said, the patent being granted shows Tesla is designing the Roadster to go fast, but it is also attempting to use unique strategies to combat any issues it might have at those speeds.

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Investor's Corner

Tesla showrooms picked clean ahead of Q3 end as demand looks strong

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17 hours ago

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September 29, 2026

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Credit: @thaichiminh1907/X

Tesla (NASDAQ: TSLA) showrooms have been picked clean ahead of the end of the third quarter of the year, as demand looks to be strong and delivery estimates for new vehicles are pushed into late 2026 and early 2027.

Tesla appears to have sold out of many of its Model 3 and Model Y trim levels in the United States, as only the Model Y RWD and Model Y All-Wheel-Drive are available for delivery before the end of the year.

Additionally, many showrooms are either completely empty or void of all but just one demo unit within the buildings themselves in an effort to bolster what could be one of Tesla’s best quarters in vehicle deliveries in recent memory.

Additionally, when I spoke to the guys at Tesla Mechanicsburg two weeks ago, when I returned the Model Y L, their third hauler of the week had just arrived, and every vehicle on it, along with every vehicle in their delivery lot, was accounted for and had a name attached to it for delivery.

Tesla saw a 25 percent increase in deliveries in Q2 compared to the same quarter the year before. The vast majority of the 480,126 units it delivered, 467,762 vehicles to be exact, were the Model 3 and Model Y.

In Q3 2025, Tesla delivered 497,099 vehicles, once again a figure that was dominated by the company’s two mass-market vehicles. Analysts have unusually wide predictions for this quarter, likely because so many firms missed the Q2 delivery figure by such a substantial margin; Wall Street predicted 408,000 cars, while Tesla delivered 480,000.

Goldman Sachs has Tesla slotted for 435,000 deliveries in Q3, while JPMorgan said it anticipates 482,000. The median guess is about 449,000 deliveries for Q3.

Interested in ordering a Tesla? Use my referral code for three free months of Full Self-Driving (Supervised) here.

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