That "Gigafactory" is from what I have understood not a complete battery factory like Tesla's GF-I, but a battery pack factory. I.e. they don't even plan for making any cells there. They will all come from their Korean(?) supplier in a separate factory. I do not know for sure if the supplier is planing on an European battery cell factory or if all the cells will be imported from Korea.
-
Want to remove ads? Register an account and login to see fewer ads, and become a Supporting Member to remove almost all ads.
Tesla Class 8 Semi Truck Thoughts
- Thread starter AWDtsla
- Start date
-
- Tags
- Future Tesla
I guess only time will tell if this is the right decision.
A lot depends on manufacturing wastage, environmental constraints, labour costs, etc. I.O.W overall is it cheaper to ship over the elements for cell production to Germany, or just the final cells to be assembled into automotive grade packs.
I think that for a low volume - or a short time - this may be the right decision. But if they do think that batteries would be the volume of their car production in the near future it's not. Then they have to do what they can to reduce the costs - including costs connected to the transporting* - and co-locate as much of the production that they can. Like Tesla does.
*)
It is among others the transport it self, insurance, having all that valuable goods under transport for a long time, currency risks, time to adopt to changing needs of battery volumes.
A point of view about the Tesla Semi.
I've been trying to wrap my head around how Tesla is going to pull off the semi for a while. And the physics just don't make sense. I'm sure they have a product, but I'm guessing it's more short "long haul" transport at best. The energy density just isn't there for hauling something from LA to the east coast (even with charging).
Even Elon Musk May Not Be Able to Make an Electric Truck Work
I've been trying to wrap my head around how Tesla is going to pull off the semi for a while. And the physics just don't make sense. I'm sure they have a product, but I'm guessing it's more short "long haul" transport at best. The energy density just isn't there for hauling something from LA to the east coast (even with charging).
Even Elon Musk May Not Be Able to Make an Electric Truck Work
My thinking has been along the same lines. The only way I can see it work is Elon is banking that solid state batteries will be in production in time for the semi. That's the only way I see a semi working. That would probably also make Tesla's flagship car the P200D or more.
Brando
Active Member
Plenty of short haul work - note Mercedes semi-truck.
Charge up during loading/unloading or even swapping should work for many.
We shall see.
Charge up during loading/unloading or even swapping should work for many.
We shall see.
Is Tesla planning to build a dedicated batch of SuperChargers for the semis? Where will they put them - at truck stops? This might be a bit expensive as think of how much power you will need at these sites - that may be an issue as a lot of truck stops are in rural or semi-rural areas where they may not have access to main electrical trunks.
Reciprocity
Active Member
My bass-ackwards analysis:
What if the Tesla Semi had 6 model 3 motors, 2 for each axel, one for each wheel. Assuming a Model 3 can achieve 300 miles on a 75KWh charge. Lets say the Semi will require 3x the Wh/m.
75 x 6 = 450KWh pack.
300 * 6 / 3 = 600 Mi range.
450KWh pack x $125/KWh = $56250 COGs - $73125 with 30% Margin,
Typical day - 8hr x 62.5mph = 500miles - Charge 80-90% per day. Slop here to allow for weather and slope, though most slopes should mostly net out over an 8 hour drive.
Free Super charging for a year: 480 / 7mpg * $2.58/gallon for Diesal x 240 working days per year = $42,459/Y in fuel cost. After the first year, supercharging costs 11-15c per KWh or cheaper with solar charging stations (500 * .11 * 220 $12,100/Y vs $42K+/Y).
Park at night at a special Semi Charging station that is setup for 8 hour 90% charge - Sleep in the cabin while charging.
or
Charge while eating at a Tesla truck stop, 80% in 1 hour with an enhanced super charger - up to 4 cables.
or
Charge at the loading dock. 11 hours with the fastest duel on-board charging solutions today. Could double the on-board chargers and cable hookups for 5.5 hour charging.
Big question.. is 450KWh enough to get 600mi range (500 at 80-90%).
Speculation: Elon said a bunch of Model 3 Motors.. could he have meant a a bunch of Model 3 sized motors, but using Rare Earth Magnets, or 4 motors for driving around town and 2 geared much higher for highway speeds? Some kinda of crazy regen from all the wheels, including the trailer? More weight, more regen though more heat.
Edit: Fixed.. thanks @MP3Mike for publicly destroying my confidence in math.
What if the Tesla Semi had 6 model 3 motors, 2 for each axel, one for each wheel. Assuming a Model 3 can achieve 300 miles on a 75KWh charge. Lets say the Semi will require 3x the Wh/m.
75 x 6 = 450KWh pack.
300 * 6 / 3 = 600 Mi range.
450KWh pack x $125/KWh = $56250 COGs - $73125 with 30% Margin,
Typical day - 8hr x 62.5mph = 500miles - Charge 80-90% per day. Slop here to allow for weather and slope, though most slopes should mostly net out over an 8 hour drive.
Free Super charging for a year: 480 / 7mpg * $2.58/gallon for Diesal x 240 working days per year = $42,459/Y in fuel cost. After the first year, supercharging costs 11-15c per KWh or cheaper with solar charging stations (500 * .11 * 220 $12,100/Y vs $42K+/Y).
Park at night at a special Semi Charging station that is setup for 8 hour 90% charge - Sleep in the cabin while charging.
or
Charge while eating at a Tesla truck stop, 80% in 1 hour with an enhanced super charger - up to 4 cables.
or
Charge at the loading dock. 11 hours with the fastest duel on-board charging solutions today. Could double the on-board chargers and cable hookups for 5.5 hour charging.
Big question.. is 450KWh enough to get 600mi range (500 at 80-90%).
Speculation: Elon said a bunch of Model 3 Motors.. could he have meant a a bunch of Model 3 sized motors, but using Rare Earth Magnets, or 4 motors for driving around town and 2 geared much higher for highway speeds? Some kinda of crazy regen from all the wheels, including the trailer? More weight, more regen though more heat.
Edit: Fixed.. thanks @MP3Mike for publicly destroying my confidence in math.
Last edited:
Reciprocity
Active Member
I confused myself, originally had 4 motors on just the back axels of the tractor, then remembered you have front wheel and no engine in the front, so I changed it to 6 and didnt change my math. Also, 6 seems more like a bunch.
That's what I'm thinking when Musk referred to the 350kw chargers as mere child's play. Those chargers would seem to be too powerful for the cars considering their batteries can barely discharge at full throttle at that amount.
As for truck stops, yes it would make sense to put them there. I wish they would have put regular superchargers in at Buc-ee's back in Texas. The more I think about it though, I'm thinking those truck stops have exclusive contracts with their gas/diesel providers. So they can only get their petro supply from a certain refinery, or network of refineries for example. I bet within those contracts, because lawyers love being lawyers, they have some sort of clause saying "and you shall not supply any other type of transportation energy source at your locations to include CNG, electrical charging stations, ect."
So let's start thinking of the power requirements. Assuming that the semi chargers will be 350kW, how many will you need at a truck stop? Ten? Twenty? If you had ten that would mean that you need 3.5MW of power delivered to the site, just for the Tesla SCs. How much will it cost to be able to deliver that much power to a truck stop on an interstate that isn't close to a major town or electrical line? Is this a big issue or not - I don't know? But I am guessing that it is and it will be an even bigger issue if these Tesla electrical semis really do take over the trucking world as then you won't need 10 SCs you will need dozens at each truck stop.
Reciprocity
Active Member
350KWh is a child's toy, think more inline with 700KWh. Maybe 2 lines that include cooling lines that come up from the bottom, which is a patent that Tesla had filed.
You would need a dedicated and very large solar farm with some giant batteries for storage. Each super station would be like the somoan island Tesla is powering:
Tesla runs an entire island on solar power
Good thing most truck stops have a lot of land around them.
Or it could be something like this:
Water-Cooled Batteries Ensure Fast Charging of Electric Ferries Across Øresund - PBES
10 kV/10MW. Yes, 350 kW is a child's toy
So, with all the hints being dropped, it sounds like the Tesla Semi event will be quite a doozy.
I expect we'll see the truck contain some combination of the following:
1. Multiple Model S/3 battery packs. 4x100kWh or perhaps 6x75kWh.
2. Multiple Model S/3 motors. One motor per wheel or one per axle. i.e. 3-6 motors total.
3. Parallel charging. There will be one charger per pack (parallel charging) meaning perhaps 4-6 supercharger cables. Even with current supercharger limits (~120kWh) this would mean an effective charge rate of up to 720kWh without the need for any costly inventions, battery swaps, etc.
4. Single-speed transmission. I think this part will be mindblowing. The torque of the motors should make this possible. Diesel trucks are 9-18 gears by comparison.
5. Ridiculous 0-60 time. I expect a sub 6s 0-60 time for the empty semi, purely for bragging rights, as it will just "fall out of the design".
In short, it means that Tesla will re-use existing battery packs and motors, and require very limited infrastructure investment (i.e. no battery swap stations). They'll demonstrate the incredible amount of product re-use that's not possible with ICE technology.
I suspect the "something special" part will be a live demonstration of some sort. Perhaps they'll take the truck to the test track for a live race with a car (Chevy Bolt or Nissan Leaf)? Or perhaps they'll demonstrate the parallel charging during the presentation.
I expect we'll see the truck contain some combination of the following:
1. Multiple Model S/3 battery packs. 4x100kWh or perhaps 6x75kWh.
2. Multiple Model S/3 motors. One motor per wheel or one per axle. i.e. 3-6 motors total.
3. Parallel charging. There will be one charger per pack (parallel charging) meaning perhaps 4-6 supercharger cables. Even with current supercharger limits (~120kWh) this would mean an effective charge rate of up to 720kWh without the need for any costly inventions, battery swaps, etc.
4. Single-speed transmission. I think this part will be mindblowing. The torque of the motors should make this possible. Diesel trucks are 9-18 gears by comparison.
5. Ridiculous 0-60 time. I expect a sub 6s 0-60 time for the empty semi, purely for bragging rights, as it will just "fall out of the design".
In short, it means that Tesla will re-use existing battery packs and motors, and require very limited infrastructure investment (i.e. no battery swap stations). They'll demonstrate the incredible amount of product re-use that's not possible with ICE technology.
I suspect the "something special" part will be a live demonstration of some sort. Perhaps they'll take the truck to the test track for a live race with a car (Chevy Bolt or Nissan Leaf)?
Or perhaps they'll demonstrate the parallel charging during the presentation.Like a tug of war contest against a Peterbuilt or some other large diesel tractor.
Reciprocity
Active Member
I get what you are saying on the perplexing nature of the Semi and just how Tesla intends to accomplish the goal. What I have been doing is trying to take everything said and tried to back into solution. A couple things that I have been working from:
1) Elon says the semi uses a bunch of Model 3 motors.
2) At that green energy thing in Wisconsin a couple of weeks ago JB said that you could literary scale up current model S to make a long range Semi.
What is a bunch.. I was thinking 1 for each wheel in the the axle or 6 total. So if you say the Semi will be the equivalent of 3 model S 100Ds with Model 3 motors (which I believe they are using to get to 1800HP as model S motors would be closer 2800HP and that is overkill.) At 1800HP and the torque you would have you would easily exceed the best performance metrics for any Class 8 Semi.
A S 100D has a range of 335 miles, so lets say they just scale that up to a class 8 rig, you would get 4700lbs curb weight x 3 or 14100 lbs which is about the weight of a standard class 8 semi. With 335 Miles of range and 300KWh pack. Now if you try to drive 335 miles in a an 8 hour shift at 60mph, you would need 500 miles of range to drive full time before resting, so you would require at least another 100KWh of pack to drive for a full shift, so you would have 400KWh of pack. That gets the rig itself to a range and power that would allow anyone to run full time with some kind of super fast charging between shifts. The question would be, is this enough to pull 60000 more lbs and a trailer. One thing I was thinking about is the regen. The regen on such a heavy vehicle would be huge and HOT. But spread out between 6 motors, maybe it could be more efficient and less prone to overheat. The other idea I had was that each of the 6 motors could have different gear or ratio so that you could have 2 motors that help you get started and 2 that are biased to the middle speeds and 2 that are for highway cruising. I dont know enough about gearing to know if this is crazy or not, but it seems like it could make the processes of getting up to speed and cruising more efficient.
I think all of this combined with the Child's Toy - Supercharger V3 could allow for simultaneous charging of 4 100KWh sub packs in the Semi at 350KWh rate or higher in 15 minutes.
Last edited:
Ciaopec
Active Member
I watched the Nikola Class 8 unveiling. Long video on YouTube but it presented the nuts and bolts of their build . Subtract the hydrogen fuel cell used to recharge and I thought it was a good idea of what Tesla might produce. There are 6 electric motors and I believe a 320Kw battery. The software limit the hp/torque to 1000hp and 2000 ft lbs and claim it will be able to hold 65mph up hills (and down with regen braking), The pitch to operators includes 1,000,000 miles of free hydrogen and probably no brake changes for over 100,000 miles. Building out hydrogen fueling station like Tesla is with chargers and have one long distance carrier with their logo and support on the side. It is a pretty slick machine with some neat software features for the trucker.
I have confidence the Tesla will be equally as nice. I know one corporation very interested in the machine.
Hope this isn't old news.
I have confidence the Tesla will be equally as nice. I know one corporation very interested in the machine.
Hope this isn't old news.
The problem is range doesn't scale directly. Drag and weight have a huge impact on energy consumption. The Model X is only a little less aerodynamic than the Model S, but it has a clear range reduction. And look at what people have said about energy consumption when towing a trailer with an X, the energy per mile skyrockets. To get 300 miles of range out of the semi, they will need considerably more than just a 300 KWh battery. They might be able to haul light loads for 300 miles with 1000 KWh, but they will need 1500 or maybe even 2000 KWh to pull a trailer loaded to the limit 300 miles.
Because of the inefficiencies of ICE, adding weight and increasing drag affect gas mileage, but the effect is far more dramatic with an EV. Added drag or added weight might reduce gas mileage in an ICE by 20-25%, but in an EV the same change could easily halve the range or worse. This is because EVs are so much more efficient to begin with. Every factor that impacts efficiency is more noticeable.
What I am unclear on is how the Tesla semi with fixed gearing is going to out pull a standard semi that has a 17:1 (T310M) or 27:1 (T310MLR) first gear along with a 2.7 or so rear axle. Total torque multiplier of ~50 or 70x the engine. A Mack MP8 puts out 1500 lb-ft of torque, so the total is > 75,000 lb-ft to the rear axle. With a 6 motor Tesla tractor, each would need ~12,000 ft-lb to match. The P100D puts out ~900, double the gear ratio to sacrifice top speed and that only gets you to 1,800 each.
Even with one axle with a much lower gear ratio (80 times lower ratio than the P100D to cover the smaller motor of the 3 [450*2*80 = 72k]) and over running (sprag) clutch, it would top out at 2-3MPH, and it wouldn't help with regenerative braking.
On the side of Tesla is that the torque is available from 0 RPM.
What am I missing?
Even with one axle with a much lower gear ratio (80 times lower ratio than the P100D to cover the smaller motor of the 3 [450*2*80 = 72k]) and over running (sprag) clutch, it would top out at 2-3MPH, and it wouldn't help with regenerative braking.
On the side of Tesla is that the torque is available from 0 RPM.
What am I missing?
Similar threads
