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Tesla Semi truck’s battery pack and overall weight explored
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.
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.
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.
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.
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.
Tesla’s two recently-defunct flagship models, the Model S and Model X, are getting a big upgrade, according to the company’s Head of AI, Ashok Elluswamy.
Older Hardware 3 Model S and Model X vehicles have been the last major holdouts in Tesla’s Full Self-Driving v14 Lite rollout, and that wait now appears to be ending.
Tesla brings closure to flagship ‘sentimental’ models, Musk confirms
At Tesla’s Cybercab launch, AI chief Ashok Elluswamy told Ryan McCaffrey that he thought the S and X build “was supposed to go out last week.” Evidently, Elluswamy expects the suite to be rolled out to those HW3 Model S and Model X very soon:
For my @Tesla friends – and specifically Model S & X owners with HW3 who are waiting on FSD v14 Lite – I spoke to @aelluswamy at the Cybercab launch, & when I asked for an ETA on v14 Lite for S/X owners, he said, “Oh, I thought it was supposed to go out last week.”
So: soon! 🙌
— Ryan McCaffrey (@DMC_Ryan) September 7, 2026
Those cars are not the current Model S and Model X, which already ship with Hardware 4. They are the pre-refresh flagships built around Tesla’s older Autopilot computer, often called HW3 or AI3.
Tesla stopped putting that computer in new vehicles years ago, which is why owners treat these S and X cars as a closed generation. Model 3 and Model Y vehicles on the same computer began receiving v14 Lite in late June 2026 and saw a wider North American expansion in July. South Korea followed as an early international market. The S and X versions of the same software never joined that wave.
v14 Lite is Tesla’s way of squeezing the current v14 driving stack onto hardware that cannot run the full AI 4 model. The company describes the process as distillation: behaviors learned on the newer computer, including reinforcement learning and offline models, are compressed so the older chip and cameras can use them as a guide.
Early descriptions put the distilled network at roughly 15 percent of the original size. The result is still supervised Level 2 driving. Tesla has been clear that HW3 cannot support unsupervised Full Self-Driving or robotaxi operation because of memory and bandwidth limits.
The feature list is what made the wait so frustrating for S and X owners, as plenty of new features are to be shipped with it.
Official notes for the first Lite build, firmware 2026.20.5.1, added parking, unparking, and reversing; arrival options for a parking lot, street, driveway, or curbside; speed profiles that stay available at all times; and start-from-park engagement. Tesla also claimed better handling of merges, forks, pedestrians, traffic lights, and cut-ins, plus fewer false slowdowns and smoother lane centering.
A mid-July follow-on build, 2026.20.6.10, added more of the Hardware 4 interface, including a standalone Self-Driving app and the ability to start a trip from Park without a brake-pedal confirmation.
Elluswamy called that version the one “likely going to wide release.”
That wide release already reached most other HW3 cars in the United States and Canada. International timing still depends on regional validation and regulatory approval. For S and X owners, the remaining work appears to be model-specific validation rather than a new software stack.
There is no official Tesla changelog or build number for those two models yet, only Elluswamy’s offhand timeline. Some HW3 drivers who already have Lite report large gains over v12.6; others have described new indecision or phantom braking. The next test will be whether the same software lands cleanly on the older flagships that have waited the longest.
Yesterday, we reported on Tesla Cybertruck getting some major adjustments from a manufacturing standpoint in an effort to make the all-electric pickup more cost-effective, more reliable, more serviceable, and more easily produced.
Tesla Cybertruck engineer reveals new changes in ‘constantly evolving’ pickup
One of those changes was the addition of a self-reinforcing polypropylene aero shield that sits underneath the truck. Previously, Tesla utilized aluminum for this, but the self-reinforcing polypropylene was more durable while also being cheaper and lighter.
Tesla has revealed another small change it made to the Cybertruck, and it has to do with the side repeater cameras.
Tesla does not wait for a new model year to improve its vehicles. On September 8, Cybertruck lead engineer Wes Morrill posted side-by-side photos of an updated side repeater camera housing now rolling off the line at Gigafactory Texas.
The triangular camera pod mounted on the front fender looks almost identical at first glance. A closer look reveals a revised contour that uses the air already flowing around the truck to keep the lens clearer in rain and road spray.
The side repeater camera was updated – the version on the left is the newer part which uses passive geometry to create airflow disturbance that better keep water off the lens while driving. No cost penalty, just pure vision improvement. pic.twitter.com/wAbXtcL1Jf
— Wes (@wmorrill3) September 8, 2026
The side repeater cameras sit in an exposed position on the Cybertruck’s angular stainless-steel body.
In wet weather, they readily collect water droplets that can degrade the image Autopilot and Full Self-Driving use for lane changes and blind-spot monitoring. Early production trucks sometimes left owners wiping lenses by hand or accepting temporary restrictions on driver-assistance features.
Tesla has added washers to cameras on certain other models and on Cybercab prototypes, but those active systems add cost, complexity, and extra potential leak points.
The new housing solves the problem with passive geometry. Subtle changes in the surround create localized airflow disturbances as the vehicle moves. Those eddies physically push water droplets away from the optical surface. Morrill called the result “pure vision improvement” achieved at “no cost penalty.” Once the production mold is updated, every subsequent part costs the same as the original.
The advantages compound quickly. Clearer cameras in rain improve the reliability of driver-assistance features precisely when they are needed most. The design consumes no extra energy and introduces no new failure modes.
New Cybertrucks built after the tooling changeover receive the updated part automatically. Some owners of trucks delivered as late as June 2026 have already confirmed they received the revised housing. Retrofit questions have appeared in replies, and the cameras appear electrically compatible, though Tesla has not announced an official service program.
A few millimeters of reshaped housing will not make headlines the way a new battery pack does, but these changes are incremental and increase the Cybertruck’s effectiveness as a vehicle over time.
This improvement illustrates how Tesla continues to refine the Cybertruck after volume production began. Better wet-weather vision, zero added cost, and no extra hardware add up to a meaningful gain in everyday usability and safety.
Tesla is rolling out a new version of its Full Self-Driving suite to some owners that comes with the massive addition of a safety feature.
Tesla is rolling out Automatic Collision Evasion with the 2026.27.6 Software Update, which started rolling out to some vehicles last night. We received the update, along with Full Self-Driving v14.3.9, as well as v14.2 Lite, which has identical release notes as the previous version and seems to have some refinements and improvements in behavior and performance.
🚨 Tesla FSD v14.3.9 is rolling out as well as 2026.27.6 which includes Automatic Collision Evasion
Brand new safety features from a software update. My Tesla gets better everytime I get one of these pic.twitter.com/ctrMiQXWhM
— TESLARATI (@Teslarati) September 8, 2026
However, most of the attention has fallen on the Automatic Collision Evasion feature, which we covered in an article last week.
The function will activate Full Self-Driving to “try to keep your vehicle safe and then continue driving. It can engage in the following situations while you are driving manually:
- Scenario 1: A frontal collision is imminent and braking alone may not avoid it.
- Scenario 2: Your vehicle detects that you are not sufficiently attentive to the road (for example, reaching toward the back seat), or that Full Self-Driving (Supervised) may have been unintentionally disengaged.”
Essentially, FSD will take over when the vehicle determines you are not paying sufficient attention or are heading toward a potential collision. The addition of this feature is incredibly useful as distracted driving is a major issue in today’s world.
Along with the new safety feature is Tesla FSD v14.3.9, which has no additional release notes compared to the previous version, but in my first drives, my first impression is that operation is great, and parking is still sort of a pain point.
Just took a 15-mile round trip to the gym and back
Pretty on par with what FSD is nowadays – really good. Not enough time to see what’s good and what’s bad, but these first rides on any version feel shockingly good. They’re all pretty identical https://t.co/WN1qTg4bhE
— TESLARATI (@Teslarati) September 9, 2026
Additionally, Tesla v14.2. Lite has arrived. A great review of that is available here:
— Zack (@BLKMDL3) September 9, 2026
The addition of an Automatic Collision Evasion feature is similar to that of other collision avoidance systems that are used by companies like Hyundai, Kia, and Genesis. These programs typically utilize radar and camera sensors to apply emergency brakes autonomously, though evasive steering in a manual driving mode is pioneered primarily by Tesla’s newest addition.
Tesla’s two defunct flagship models are getting a big upgrade
This tiny Tesla Cybertruck adjustment has big advantages
