Tesla Semi Specs Revealed
Holiday surprises aren’t done being delivered, because we just got some hard numbers on the Tesla Semi!
On December 31st, twitter user @greentheonly dropped a spread of images depicting certain systems of the new Tesla tractor vehicle, and was reportedly sourced from Tesla’s online parts catalogue.
We can see several systems spread over the images, and Green specifically calls attention to the modular battery packs - which he reports is rated for 1000 volts - the “mega cooling” modules, and the two rear axles - named Torque and Efficiency.
We can identify the Efficiency axle with its single engine in the very back, and the Torque axle with a pair of engines just in front of that. That Torque axle is reportedly only engaged when the vehicle is under heavy load or acceleration, otherwise the Efficiency axle - which is optimised for constant highway speeds - is what the Semi runs on.
As for the cooling, it looks as though we can spot that in this image where we can see a big coolant tank where the charging port is (near the rear wheels) - which makes sense when we remember that Tesla is going to be charging their Semis at about 1 megawatt.
We can also see that the huge batteries are separated into three sub-packs, which is what seems to be tipping people off to the modularity aspect. There’s less in the way of solid numbers available, the images on Twitter and this chart released by NextBigFuture on December 29th, help to confirm the modularity of this new battery pack.
The two different entries - a 500 mile and a 300 mile variant - could have meant that Tesla had already designed a smaller battery pack for the Semi and was prepared to produce both. But the image from the parts catalogue shows us that Tesla was smarter than that - they made sub-packs that can be disconnected and removed according to a user’s needs.
The image shows that the batteries are organised into three rows of subpacks, each containing 3 batteries.
What’s more, the chart from NextBigFuture shows that the 300 mile Semi weighs 5500 lbs less than the 500 mile Semi. Even though these are rough numbers, we’re seeing that removing the 390 kilowatt hours-worth of batteries allows the Semi to haul slightly more at the cost of less range - while still keeping efficiency and power.
This is probably the biggest reveal of the bunch, because the modularity allows for many more different use-cases for the Tesla Semi, and will likely attract more buyers. Not every company needs a 500 mile variant, and knowing that Tesla could refit a shorter-ranged model to suit a specific need - without having to redesign for a smaller battery pack - means Tesla can have more variants on the road faster.
Aside from the batteries though, we do have some other very interesting information that confirms the Semi’s capacity which was shown back at the Delivery Event in December.
There is a Vehicle Identification Number - a VIN label - included with the images that gives us some hard numbers. Let’s look at that for a minute.
Like any other vehicle, this label lists things like rim dimensions, tire pressures, and the gross vehicle weight rating or GVWR. This is what we’re interested in.
The label puts the Semi’s rating at 48,800 lbs. This means that the Tesla Semi can safely operate at that maximum load - including accessories, the driver’s weight, fluids (in this case this would include things like windshield wiper fluid, but not fuel), any cargo on the tractor itself, and the force that the trailer’s hookup is expected to add to the tractor.
Almost 49,000 lbs of capacity is definitely not bad. Most modern large-scale tractors - like the Peterbilt 579 - have a GVWR of 80,000 lbs; but that’s on the high end, long-haul side of the industry. With the numbers from that VIN label, the Tesla Semi would be comparable to a 2006 Peterbilt 379.
But we don’t just have the VIN label to go off of. We have the chart from NextBigFuture to help get a more complete picture.
The tractor weight for the 500 is listed as 26,000 lbs - which would likely be referring to the curb weight of the vehicle - or the tractor’s weight with all its fluids topped off and ready to drive.
Then, we’re shown the Payload weight - 44,000 lbs for the 500 mile Semi, and 49,500 lbs for the 300 mile variant. (The 300 mile Semi can carry a little more because it’s not hauling extra batteries)
The GCW - or Gross Carry Weight - confirms that this payload number is separate from the tractor weight.
And this is why some people were confused, because 48,800 lbs of GVWR doesn’t allow for the payload capacity we saw the Semi pull back at the Delivery Event in December.
But a Semi’s capacity is actually calculated based on its axles. And the clue for that is on the Twitter VIN label.
You can see on the image that there’s a heading for GAWR - that’s the Gross Axle Weight Rating. Those numbers line up to show that the tractor’s total gross weight rating is spread over the axles - with the rear two providing most of the capacity. So while the Semi’s GVWR is calculated to include things like the trailer’s hookups and the force those will impart on the vehicle - the trailer's axles add to the overall GVWR of the vehicle, raising it to about 82,000 lbs - right where Elon said it should be.
While we’re still relying more on sleuthing to get solid numbers, we are seeing more and more raw data now that the Semi is out in the world and hauling freight - and it’s encouraging to see that most of the data the community had pieced together last year is matching up with more official benchmarks, like the VIN label.
And it’s especially great to see the data laid out in that chart, showing just how much more efficient the Tesla Semi is than any of their competitors. I’d bet Tesla engineers are feeling vindicated.