Just over five years ago (which feels like it’s been a decade, I know) Tesla unveiled its idea for a semi truck of the future. The Tesla Semi promised to revolutionize the trucking industry with an EV semi capable of hauling a full load 500 miles on a single charge. Development of the Semi has been a rollercoaster. Back in 2018, Musk said that the Semi would have four Model 3 motors and release in 2019. That year came and went without a Tesla Semi, with Musk saying that it would release in 2020. Then, the release date of 2020 became 2021, then 2023 was even hinted at as the release. Along the way. Tesla said, at least in an earnings report, that the delays were due to a limited supply of batteries and the supply chain shortage. But now, it seems that Tesla has pulled it off, so what are truckers getting with a Tesla Semi?
The Meat And Potatoes
Tesla’s Semi delivery event both answered a lot of questions and frustratingly left a lot completely unanswered. I’ll start with what you’re not about to learn here. Elon did not reveal how much the Tesla Semi weighs. He also did not reveal its actual horsepower, torque numbers, price, or battery capacity. But don’t fret, because Elon did reveal some pretty sweet details. The biggest one, I think, is its range. Recently, Elon Musk Tweeted that a Semi loaded to 81,000 pounds completed a 500-mile drive. Musk didn’t indicate how many times the truck had to be charged for the trip. But at the event, he clarified that the truck went the whole distance on a single charge. And as proof, he brought a timelapse of the truck doing the whole trip.
Even then, it seemed unbelievable. Freightliner, an established player in the semi truck space, has its eCascadia, which will do 230 miles at best with its 438 kWh battery. Volvo’s VNR Electric can go 275 miles with its 565 kWh battery. The Nikola Tre BEV claims up to 330 miles from its 733 kWh battery. And the rest of the competition doesn’t even come close. So how did Tesla beat the competition so hard? Musk gave a hint when he said that the truck worked out to just less than 2 kWh/mi on the 500-mile drive. Based on that, our contributing engineer Huibert Mees said: And, he may be onto something. While Musk did not reveal the batteries, he did reveal other details. The Semi is a parts-bin special. Musk says that it uses inverters, drive units, power electronics, HVAC, and infotainment from other Tesla models. For example, the drive units are said to be “essentially” the same units from Tesla’s Model S and X Plaid cars.
Elaborating further, Musk says that the Semi uses the three Plaid motors. This is one fewer motor from the proposal to power the Semi using Model 3 motors. However, using the more powerful Plaid motors apparently means no range or power loss compared to using four Model 3 motors. Musk went on to say that in the Semi, one motor is always running. However, when more torque is needed for climbing or when more acceleration is needed for passing, the two additional motors have an automatic clutch system to seamlessly integrate into the action. This configuration is said to give power when it’s needed and low consumption when you’re cruising. One thing that confused me about this is when Musk said that just one of the football-sized Plaid motors is more powerful than a diesel semi engine. Assuming that the Semi is making the same amount of power as a Plaid, it’s making 1,020 horsepower. Class 8 semis commonly run 400 HP to 600 HP or more depending on configuration. Heck, you can buy RVs that make 605 HP. So, that claim doesn’t currently check out unless there’s more power. On that note, Musk says that loaded, this thing can hit 60 mph in 20 seconds, and there’s enough power to accelerate up mountains.
The Semi is running on 1,000 Volt architecture. To charge the beast, Musk says that Tesla developed a liquid-cooled charging connector capable of delivering 1 megawatt of power. Apparently, it will be good enough to charge whatever battery is in the Semi to 70 percent in just 30 minutes. This architecture, Musk said, will make its way down to the Cybertruck. It also has a traction control system to prevent jackknifing and a regen system so strong that Musk says that the Semi can go down a mountain without its driver needing to touch the brakes.
There’s Other Good Stuff, Too
Alright, so Musk didn’t reveal the Semi’s price, weight, horsepower, or other important stuff. But there were more goodies revealed in the event. For one thing, since there’s no diesel engine in the way, Tesla was able to give the Semi a bigger cab. Despite its looks, this is a day cab. However, this is a day cab that’s big and tall enough for a driver to stand inside of it. Senior Manager of Semi Truck Engineering Dan Priestley said that you’ll be able to do stuff in the safety of the cab like get dressed. And there’s ample room to store tools.
Priestley also noted convenience features like a suspension drop to make hooking up to a trailer easier and an automatic light test to make sure your lights are working. These features, Priestley says, are to make driving the Semi really easy. And for Tesla, the Semi helps it achieve its mission of pushing sustainable energy. Citing a 2021 Tesla report, Musk said that Class 8 trucks make up just 1 percent of all vehicles in the United States. However, the report continues, they contribute to 20 percent of U.S. vehicle emissions and 36 percent of U.S. vehicle particulate matter. Musk wants to combat this by putting 50,000 Semis on the road in North America. And yes, this graphic seems to hint that there may be a Tesla robotaxi concept in the future?
At any rate, the Semi is finally hitting the road with customers. The first deliveries went out to PepsiCo, and a Pepsi-branded truck made an appearance at the event. Pepsi’s Frito-Lay division also completed its first cargo run. As more Semis roll out, Tesla says that it will use the Semi for its own operations between suppliers and factories. Thus far, things sound good, but we really want to know more about how much it weighs with those undisclosed batteries. How much the Semi weighs will end up determining how much of the 82,000 pounds allotted to electric semis will actually be used for cargo. And the price may determine how close Tesla will get to hitting its production goals. [Correction: An earlier version of this story said that Musk was accompanied by Tesla Chief Designer Franz von Holzhausen. He was accompanied by Senior Manager of Semi Truck Engineering Dan Priestley. We regret the error and thank you, readers!]
What if we got these upgraded to full self-driving by putting them on some sort of guided surface or track instead of on the open highway? They could have metal wheels instead of rubber as well, which would massively cut down on rubber particulate pollution. And then you could use this guided “track” of sorts to conduct power directly to the motors instead of needing to haul around 12,000 pounds of batteries made of scarce lithium? Hell I bet with the weight savings and more available power you could pull multiple trailers with one cab, maybe even dozens of trailers! Is anyone working on this? On the power point, the Plaid motors make 1000 hp when hooked up to 400V. If this is really a 1000V architecture, then presumably they’re making more power in this application. At one point, they said something about the truck having a total of 3X the power of a regular diesel, so I’d guess each motor here is making about 500 HP, for a total of 1500 or so. This thing’s going to have ~10 times the battery, which would imply 10 times the battery power. (In practice it’ll probably be less than that, as you don’t need that much power, and may be able to optimize the cell construction for more energy density than the cells used in the Plaid cars, instead of power density, to reduce weight and volume.) Combine that with, as you point out, a higher voltage system, which all else being equal, would be optimized for higher RPM operation, and I believe this means that you can get higher power when operating at higher RPM, and you could probably get each motor north of the 600ish hp that US-market semis top out at. I’d also guess that the highway motor would be geared such that it’s at peak efficiency (not into field weakening) somewhere around 55-65 MPH, where the acceleration motors would be geared such that they’re at their absolute maximum RPM at the Semi’s top speed (I’d guess that’ll be somewhere around 80-85 MPH just because of the highest speed limits for semis in the US, AFAIK, being 80 MPH). So 1000V increases the continuous power possible by 2.5x vs 400V, because continuous current should stay the same, assuming the motor windings haven’t changed and that the IGBTs used in the inverter retain the same current rating as those in the car/CUV lineup. No, but seriously, I totally agree with you.. What no one is talking about is how we will meet the overwhelming demand in providing power for all the EV’s once the brainless legislature is put into place to phase out all ICE vehicles.. No one is talking about nuclear, and for sure we can’t meet the demand with solar and wind.. “Oh, but these vehicles will be smart and will charge off peak”.. YEs, so will every other EV… Another thing is the disposal of all the lithium batteries. Sure the vehicles aren’t dumping emissions into the atmosphere, but what about production, disposal and pollution of all the battery packs. On top of that the associated emissions and pollution that comes with the production of energy for all the EV’s? Literally no one is talking about this.. Everyone seems to be hoodwinked with the “It’s good for the environment” nonsense. I know, for example, that nuclear fusion experiments use flywheels and motors/generators for the megawatts to gigawatts of power that they need. In summary, these things need to come with fast swappable battery packs. This works against the theory their battery management is better because they’re just running a larger battery. Also, while he says it will tow up a 6% grade, I’m going to go out on a limb and guess there wasn’t a 6% grade on the 500 mile test. And I can visually see that none of this happened in anything like normal temperatures for the rest of the country this time of year. https://twitter.com/tesla/status/1598490134357610496?s=46&t=WTGV0cLVb8Dtdy_zq2B8Zw They noted that the truck can recapture a great deal of energy going downhill, so terrain isn’t as big a deal as you might think, which tracks with my EV experience. Your weather point is excellent, though. However, if it was fully integrated, that would guarantee no jack-knifing as the trailer could apply more braking force than the hauler. I’ll use 100% to 10% for the first charge, and assume the 30 minute recharge gets from 10% to 70%, not 0% to 70%. And, as Tesla hasn’t stated a speed for their range claims, I’ll run the numbers assuming both 55 MPH (the speed which Tesla used for their 97% to 4% 500 mile run, due to California speed limits) and 65 MPH (a more typical trucking speed in the US outside of California). Important caveat: if their claimed range speed is at 55 MPH, the 65 MPH numbers will be wildly inaccurate. So, a bit on trucking laws in the US: In a maximum of 14 hours on-duty, you can drive a maximum of 11 hours. You can drive a maximum of 8 hours without taking a 30 minute break. 90% (100 to 10%) of a 500 mile range battery is 450 miles, and 60% (70% to 10%) is 300 miles. Assuming the range is at 55 MPH, it would take 8h11m to get from 100% to 10% – however, you have to take your break by 440 miles, before getting to 10%. Then, after taking your break and recharging to 70% (in reality, probably a bit over 70%), it would take 5h27m to get back to 10% – you’re out of drive time for the day by 275 miles, again before getting to 10%, at which point you’ll need to take your 10 hour rest before driving again, and can do an overnight charge. Essentially, it has enough range, with a significant buffer, to go an arbitrary single driver distance. Assuming 65 MPH, it takes 6h55m to get from 100% to 10%. Then, you take your break, and recharge to 70%. It would take 4h37m to get from 70% back to 10%, but you’d need to stop at 265 miles, before getting to 10%, and you’d need to take your 10 hour rest. Now, if you’re doing team driving, all of this is blown out of the window, because you can start your rest period while the other driver drives, and they’ll have to wait to start their shift for 30 minutes to get back up to 70%, and then if the range is at 65 MPH would have to make an additional charging stop that isn’t legally mandated. (If the range is at 55 MPH and that’s the speed they’re doing, they’re only leaving 6 minutes of drive time on the table, at which point it’s fine, except for the shift changeover time.) It’s still not too bad, but it’s not as fast as diesel. I like the thinking behind the drive train layout,and the shared components.All very sensible. That driver has a cast iron bladder. Only one stop in what,six hours? I’m unconvinced the center driving position is as safe.We put drivers on the critical side for a reason! Head on’s are the worst kind of wreck. Im super curious how pepsi uses them. Hauling frito lay’s will be almost too easy while cans of drink will always hit the weight limit. Bladder size is pretty irrelevant in conversations about EVs in general*. But doubly so when it comes to trucks, since the driver can and will just pee in a bottle rather than stopping.
- (Doesn’t matter if your EV battery’s runtime duration is the size of your bladder when your destination has no charger, ’cause you’re still stopping to pee at some charging station frustratingly close to where you actually wanted to be rather than at your destination. That driver would rather have a 2-bladder sized battery every time.) 10 Model S batteries=1200 lbs x 10=12000 lbs Semi engine=3000 lbs + 1000 lbs fuel (this is a high estimate for a day cab)= 4000 lbs 12000 – 4000 = 8000 lbs difference with batteries alone….for a day cab. I know I’m not figuring other drivetrain differences (motors are lighter than diffs I’m sure), but that is an insane amount of weight difference. Even if they offset some of that, it will still be insanely heavy, limiting it to only light load operations…. While I support electric cars, I just don’t see full electric as the solution for semis. Tech and infrastructure has to go a long way before it is widely viable in the industry. If the Tesla semi had come out a decade ago it would have been alone in the market and had time to sort out its infant reliability issues, but at this point there are already EV trucks for sale by companies that know the market and product requirements. Tesla should have developed a driveline to sell to other truck makers, and spent the engineering time and money saved updating their EV car lineup. Also, most local trucking operations run their trucks in 2 shifts (2 drivers use the same truck on alternating 12 hr shifts). So charging time will be a factor in profitability for trucking companies as well. It takes less than 10 mins to fuel a diesel semi, and they all hold enough to operate for at least 12 hrs. Any down time for charging will be costing trucking companies big money. https://en.m.wikipedia.org/wiki/Dynamic_braking To get to a speed (or altitude), you need to exert energy. Since nothing is 100% efficient, you use more energy to get to a speed or altitude than you can reclaim. That being said, let’s say you charge in Denver and drive downhill toward Chicago. It’s possible that you’d have too much energy to recover (though, again, you’re quickly burning electrons just by driving). In that case, regular brakes do the job.
