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Tesla Semi truck’s battery pack and overall weight explored

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The big question on everyone’s mind–at least on the minds of those who understand the freight transportation industry–is how much the Tesla Semi might weigh. If Tesla’s all-electric semi truck is to be competitive at all, it must be capable of carrying the same loads as current-use semi-trucks in the Class 8 field do.

A big point of contention from nay-sayers and those in the trucking industry who understand logistics was the lack of announcement of the Tesla Semi’s actual weight. Plenty of press was given to the much-touted “80,000-pound capacity” number bandied around by CEO Elon Musk during the truck’s unveiling late last year. That number, however, refers only to the gross vehicle weight (GVW) of the Tesla Semi and is, in fact, exactly the same number used by every Class 8 truck on the road. They’re called Class 8s, in fact, because the 8 refers to that 80,000-pound total vehicle capacity.

What wasn’t given by Tesla was the gross vehicle tare weight (GVTW) of the Semi. This is a far more important number. Where the GVW gives the total capacity of the truck in terms of how much its freight plus the truck itself can weigh, the GVTW gives just the weight of the truck, sans trailer and freight. This number tells logistics experts how much actual freight and trailer the truck can haul legally.

For example, a typical “day cab” configuration 18-wheeler with a diesel engine weighs roughly 32,000 pounds with a relatively lightweight box trailer attached and full fuel tanks. That leaves about 48,000 pounds of freight capacity for the truck. That’s important because, although the truck won’t be loaded to capacity every time, it will be expected to be capable of carrying up to about that weight. Most big rigs on the road are capable of hauling 44,000 or more pounds worth of freight, depending on configuration and trailer type.

Having experience with driving commercial trucks in the past, once hauling a refrigerated trailer that had a freight capacity of 44,500 pounds, I learned that some industries count on freight capacity as part of their logistics costs and will literally fill a truck to its maximum in order to minimize those costs.

In logistics, weight and total freight capacity are highly important metrics in the overall scheme.

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What We Know

Thinking about that, then, let’s look at what we know of the Tesla Semi and its potential weight. We know that the truck uses four independent electric motors that are derived from the Model 3, that it has an energy consumption of less than 2 kWh per mile, and that it can be charged to up to 400 miles in about half an hour. We also know that Elon promised 300 to 500 miles of range in total. On that latter point, it’s pretty clear that a “lower range, cheaper option” will be offered as has been done with most of Tesla’s vehicles to-date. So we can assume a 300-mile version and a 500-mile version will be forthcoming for the Semi.

We also know that the Tesla Semi had eight ports in its charging plug array. We saw this at the unveil in some close-up photos.

It’s clear to us that even if the Tesla Semi isn’t to become a big player in the trucking industry, the idea behind it will change things forever.

 

What We Don’t Know

What we don’t know is whether Musk and Co have something up their sleeves for the batteries. Much of the speculation regarding the Tesla Semi has been in regards to Tesla Semi’s massive battery pack.

In actuality, having a huge battery breakthrough on a vehicle like the Tesla Semi would not necessarily be a good thing for business. If there is a huge breakthrough, then all bets are off and most of our speculation in this article is moot. That would, however, mean that the sales potential of the Semi would be far lower than it would be otherwise because one thing that logistics companies and fleet managers aren’t interested in are flashy new, breakthrough, and (most importantly) untested, unproven technologies.

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To a fleet manager, those phrases mean “breaks often, expensive to fix” and the potential positives will be ignored because of that. No one who wants to keep a job as a fleet manager or logistics purchaser will gamble on something unproven. Like new battery technology for a truck whose primary cost will be in its batteries. Likewise, unless there is a clear benefit in some terms other than pure business (like marketing or potential tax breaks), no board of directors will risk shareholder wrath on new tech either.

Close-up look at Tesla Semi’s drivetrain from underneath

We can say, as a side note, that most of the orders that have been placed for the Tesla Semi thus far are from corporations and companies who are doing business in areas where the marketing bonanza and potential tax incentives for laying down those relatively low-cost deposits are immense. Most of the companies involved have already invested heavily (and very publicly) in alternative fuel options outside of Tesla over the past few years. We also note the timing of both the Tesla Semi’s announcement (and order-taking) and the before-2018 rush by potential customers to put in deposits.

We reiterate that our not knowing if Tesla has some kind of big battery breakthrough announcement is a big “if” in our analysis here.

 

What People Smarter Than Us Have Said

Some people who know more than we do about things like math and engineering science have crunched the numbers on the Tesla Semi’s battery potentials. Over at Engineering.com, John Ewbank broke the results down into layman format. Here’s the gist.

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If the Tesla Semi uses 2 kWh to travel a mile, then a 500-mile range means 1,000 kWh of power. That is not the actual size of the battery, though, as the charging requirement would preclude a huge pack.

In order to get 400 miles in thirty minutes of charging, Ewbank notes, the charger would have to be 1.6MW to achieve the 800kWh of promised charge in only 30 minutes. Charging at that rate is not possible because the result would be arching in the pack, which would surely be akin to the next Boring Company Flamethrower meme when Semi trucks begin to explode in flames during charging as a regular event. So the charging has to be split up.

Tesla Semi Megacharger port could support 1 MW of power.

The answer is simple, of course, and may explain the strange layout of the eight-port charging hub shown on the Semi at its unveil: there are four battery packs.

Instead of one big pack, four smaller packs (one for each motor, even) are used and are thus charging separately from one another, but simultaneously. Based on Tesla Semi’s Megacharger port configuration, this would likely mean that four of them are positive sides and the other four are grounds. Allowing for a single, huge wire to be plugged into each. The controls for the charging system interface may be plugged in separately (perhaps the oval-shaped black thing to the side?).

What This Adds Up To

We add up that bit of information plus what we know about the truck and get an estimated weight. Using the current weight of a Tesla Model S battery pack at 540kg per 90 kWh, we can do some simple math to estimate the Semi’s batteries would weigh about 6,000 kg. We aren’t sure about the new battery weights for the upcoming battery updates, but we can assume a 10-15 percent reduction from several factors (storage density, improvements in chemistry, packaging lightening) without being too aggressive or overly optimistic. Going with the fifteen percent reduction, that 6,000 kg drops to 5,100 kg. That’s about 11,244 pounds.

A conventional tractor, as we’ve said, has a tare weight of around 32,000 pounds when fully fueled and with a lightweight box trailer in place. Remove the trailer and the truck itself is about 22,500 pounds. It’s difficult to then go to just the weight of the powertrain components and fuel, but they’re considerably less than 11,000 pounds in all.

Tesla Semi spotted doing a tire-shredding acceleration run down in the wild

Looking at the shipping weight for a crated engine and transmission for a Class 8 truck, we can see that they weigh about 8,000 pounds on average. Add in fuel and other components and another 1,500 pounds (at most) are put on the truck. We then assume that the rest of the truck (framing, braking systems, air compressor, etc) are about the same for the Tesla Semi in order for it to meet Class 8 standards. So we call those a wash.

That means that the Semi, under our estimates, is roughly two tons heavier than would be a standard day cab big truck in the Class 8 category. This means the Semi would be that much less capable in terms of freight hauling that’s offset by its unprecedented all-electric performance. That amount, however, is probably not enough to stop the primary buyers of a day cab truck like this from balking at a purchase. The weight difference alone would be repaid in potential fuel savings, tax incentives, green marketing, and maintenance costs.

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The trouble will come with cost differences. If the ROI is not there, most logistics buyers won’t write any purchase orders. But at least we can say that as far as we can tell, the weight differences of the Tesla Semi alone aren’t going to be a huge bar against entry into the trucking industry.

Aaron Turpen is a freelance writer based in Wyoming, USA. He writes about a large number of subjects, many of which are in the transportation and automotive arenas. Aaron is a recognized automotive journalist, with a background in commercial trucking and automotive repair. He is a member of the Rocky Mountain Automotive Press (RMAP) and Aaron’s work has appeared on many websites, in print, and on local and national radio broadcasts including NPR’s All Things Considered and on Carfax.com.

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SpaceX’s Starfall just went from secret to storefront

SpaceX now pitches Starfall missions with 1,000 kg payloads, weeks of microgravity, and Starlink connectivity.

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An artist’s illustration of a SpaceX Starfall capsule reentering Earth’s atmosphere. (Image: SpaceX)

SpaceX has put up a dedicated commercial page for Starfall, its disk shaped reentry capsule, laying out for the first time what customers actually get when they book a flight. The page, live at spacex.com/starfall, pitches “affordable, routine access to microgravity” and invites companies to get in touch about flying manufacturing, research or testing payloads.

The specs are short and specific. Each Starfall mission carries up to 1,000 kg of payload, supplies 1 kW of power and connects through an Ethernet interface. Mission length is tailored to the customer, and the payload stays online the entire time through Starlink, which means researchers can pull data from an experiment while it is still in orbit instead of waiting for splashdown.

SpaceX is launching a secret spacecraft that could change how things are made in space

SpaceX is aiming the service at three markets. Biomedical customers are told they can grow stem cell organoids, replacement tissue and layered biomaterials. Pharmaceutical companies are pitched on protein and small molecule drug crystals, which form smaller and more uniform shapes without gravity driven convection. Materials science rounds out the list, with semiconductors and other next generation materials grown in vacuum and microgravity.

The page also makes clear which rocket SpaceX is counting on. “By launching on Starship, Starfall brings a reliable and scalable cadence previously unavailable to the market,” the company wrote, contrasting weeks of continuous microgravity with the seconds offered by drop towers and parabolic flights. No price or first operational flight date is listed.

The commercial push is a sharp turn from how Starfall started. SpaceX said almost nothing about the capsule ahead of its first flight in June, and nearly everything known came from FAA and FCC filings describing a disk about 10.2 feet wide and 2.5 feet tall that can return 2,200 pounds of cargo. By its second flight on the Bandwagon-5 rideshare in October, Starfall was listed by name on the mission page, though SpaceX still did not say what it carried.

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Customers appear to be lining up. SpaceX said in its third quarter results that it signed three commercial Starfall missions during the quarter. On the earnings call, President Gwynne Shotwell described the capsule as providing “routine relatively low cost access to microgravity environments for scientific research, including improving our understanding of diseases like cancer and diabetes,” and said the three new missions would fly on Starship.

The branding effort extends past the website. SpaceX added a Starfall T-shirt to its online store on Monday as part of a batch of new merchandise, giving the program a place next to Starship, Starlink and Starshield in the company’s lineup.

The move also puts SpaceX in more direct competition with companies it launches. Varda Space Industries, which has built much of the in-space manufacturing market so far, flew its W-Series 7 capsule on the same Bandwagon-5 mission as Starfall in October. Varda’s capsules are roughly three times smaller than Starfall, and SpaceX controls the ride to orbit for both.

Starfall’s near term cadence depends on Starship. SpaceX is preparing for Flight 15 after completing static fires of Ship 42 and its Super Heavy booster in late October, and is aiming to catch both stages with the launch tower on that flight.

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Grok Bot users hit with weekly limits early, Elon Musk explains what happened

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Credit: Grok Bot

Elon Musk said weeks ago during SpaceX’s third-quarter earnings call that the company’s Grok Bot, its autonomous AI Agent platform, was showing “the fastest growth of a product” that he’d ever seen in his life.

Now, SpaceXSI is scaling back Grok Bot users’ weekly limits, much to the surprise of those who have relied on it to take away monotonous tasks in their lives.

Elon Musk’s terse November 1 reply on X captured a sharp tension in the early days of agentic AI. Responding to a user who asked for a Grok Bot usage reset after hitting 100 percent with four days still left on the weekly cycle, Musk wrote: “The cost of serving Grok Bot was unsustainably high relative to revenue.”

The post arrived amid a wave of similar complaints from paying subscribers whose meters had jumped unexpectedly toward or to the limit, sometimes overnight and with little corresponding activity. It also stood in clear contrast to statements Musk had made only days and weeks earlier.

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On the SpaceX third-quarter earnings call in mid-to-late October, Musk had described Grok Bot in almost the opposite terms. He called it “the fastest growth of a product that I’ve ever seen in my life” and said he had “never seen anything grow this fast.”

Company figures put paid weekly users at roughly 800,000 earlier in the month, more than doubling over the prior period. Daily active users had climbed from under 100,000 in early September to over 600,000 by late October.

Musk emphasized that the product has no free tier and that users appear to be getting real value beyond what they pay. In other remarks, he noted that usage per user was rising rather than declining, the opposite of the usual decay pattern for new software.

Grok Bot, launched around August, functions as an always-available agent with its own persistent cloud computer; it can schedule, research, shop, browse, and execute multi-step workflows even after the user steps away. Access is bundled into X subscription tiers (roughly $30, $100, and $200 per month) and certain Cursor plans, drawing from shared weekly usage pools whose exact sizes have not been publicly detailed.

The economics of that model are what Musk’s November 1 post put in the spotlight. Agentic systems burn far more compute than ordinary chatbot exchanges. Each task can trigger repeated model calls, tool use, web actions, and sustained background work.

When growth is as rapid as Musk celebrated, the absolute compute bill scales quickly even if average revenue per user stays fixed under flat monthly subscriptions. Industry observers noted the opportunity cost as well: the same GPUs can be rented to other AI labs at higher rates.

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A simple back-of-the-envelope comparison circulating after the post illustrated the gap: if every reported daily user paid the top tier, annualized subscription revenue would still be modest relative to the scale of compute infrastructure SpaceX is building and leasing to companies like Anthropic.

Some users also reported possible dashboard anomalies around the same period, though Musk’s framing treated the underlying cost-revenue imbalance as the core issue rather than a pure metering glitch.

The juxtaposition is the core of this exchange. Within roughly two weeks of publicly framing Grok Bot as an unprecedented success with strong unit economics and no free tier, Musk acknowledged that serving the same product had become unsustainable relative to the revenue it generates.

For the broader industry, the episode underscores a structural challenge of the agent era: demand is real and growing faster than many expected, yet the cost of fulfilling that demand through always-on, multi-step agents can outrun subscription pricing before companies can adjust limits, introduce metered billing, or raise prices.

Musk’s reply did not promise an immediate reset or higher allowances; it simply stated the constraint. In doing so, it supplied a rare, explicit public data point on the unit economics of a high-profile AI agent just as adoption numbers were still being celebrated as the fastest in Musk’s experience.

The tension between rapid, paid growth and the compute required to deliver it is now on the record.

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Tesla owners who tap Emergency Drive Away for fun are in for a surprise

Tapping Activate on Tesla’s Emergency Drive Away reportedly triggers a $539 service bill without moving.

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Tesla owners who press Activate on Emergency Drive Away may be on the hook for a service bill even if their car never leaves the Supercharger stall.

Yaro, who posts about Tesla service cases on X as @Tutrifour, said a customer called after tapping Activate while still plugged into a Supercharger. The owner was about to pull away, remembered the cable was still connected and stopped. The car never moved, but the touchscreen showed a red alert reading “Emergency Drive Away has been activated” with “Service is required” underneath. A Service Mode screenshot showed the active alert BMS_a228_EmergencyDriveAwayServiceRequired, which Yaro said only Tesla Service can clear.


The cost of clearing it was the bigger surprise. “Don’t press Activate on the new Emergency Drive Away feature on your Tesla because service charges $539 to inspect the charge port and to clear the alert. Yes, even if you didn’t move the car an inch,” Yaro wrote.  The $539 figure comes from that single case, and Tesla has not published a set price for the inspection or commented on the post. Yaro also noted that the car would still charge with the alert on screen.

Tesla launched Emergency Drive Away on October 1 with software update 2026.38.3, letting drivers pull away from a U.S. Supercharger with the cable still attached, as Teslarati reported. To use it, a driver shifts into Drive while connected, holds the brake and taps Activate. The prompt warns that driving with the cable connected will damage the vehicle and the Supercharger, and that short camera recordings will be shared with Tesla.

Tesla Charging has been clear about what follows a real activation. Repairs to a Supercharger stall can run up to $25,000 depending on the site, a service visit for the car’s charge port is mandatory, and deliberate misuse “will invoke additional penalties.” What the company had not spelled out is that the service requirement is triggered the moment Activate is pressed, not the moment the cable breaks away.

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From an engineering standpoint, that is the cautious choice. Once Activate is pressed, the car cannot be sure the charge port latch was not stressed, so flagging it for inspection removes the guesswork. It also means the button carries a price on its own, which is a stronger deterrent against casual use than any warning screen.


The report follows the feature’s first known real world use, when a driver in Austin during F1 weekend appeared to trigger it by accident and dragged the Supercharger cable along with the car. The Reddit user who filmed it said the driver seemed to have only half read the prompts.

For owners, the takeaway is to treat the red prompt as a stop sign. If it appears after shifting out of Park by mistake, shift back and unplug the normal way from the touchscreen, the Tesla app or the button on the charge handle. Activate is meant for moments when staying at the stall is the bigger risk, and Tesla is now pricing it that way.

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