Tesla Semi

[AB4EJ]

In reading thru this thread, it seems like everyone is assuming/convinced that the Tesla Semi has to be a long-haul truck. I'm not so sure that this is really the sweet spot for an electric truck - you have to have battery swapping to make it practical. There is another type of semi application that may work better, at least at this time: the "milk run." These are semi-trucks that carry freight around a relatively short route. Think about Just-in-time and just-in-sequence manufacturing: the supplier plants are clustered around (usu. within 25 miles) of the assembly plant, and trucks take regular routes delivering parts, and taking back racks and returnable containers. The trucks spend quite a bit of time parked at one plant or another (being loaded/unloaded), and could be conveniently plugged in to a high-power (i.e., 300 kwh or whatever) while docked, without detracting from anyone's productivity. Included in this could be the trucks that deliver grocery items to supermarkets, soft drinks and beer, etc., from local distribution warehouses to retail locations. If this is targeted as the application for the Tesla Semi, it has a lot of advantages:

• it puts the electric capacity where there is currently the most need to reduce air pollution (within cities)
• no need for a battery swapping infrastructure
• it makes dual use of the time trucks spend loading and unloading
• speeds are generally lower in cities, reducing energy loss due to drag - this increases range

Just my 2 cents.

 

[AudubonB]

Well, it's a long thread and you can be excused for not having read each post. A fair number of pontificators also have made that observation.

Regardless, long-haul trucking represents in many ways the shibboleth with which the concept of EV viability likely will be determined with finality.

 

[jhm]

Well, it's a long thread and you can be excused for not having read each post. A fair number of pontificators also have made that observation.

Regardless, long-haul trucking represents in many ways the shibboleth with which the concept of EV viability likely will be determined with finality.

Well, that made me have to look up the word "shibboleth."

If you look at folks expressing disbelief in electric trucks, they use jump to the most extreme uses cases, where teams of drivers take 40 tons thousands of mile across the outback with nothing so much as a piss brake to sustain them. So obviously they need 300 gallons to go 1200 miles at a shot and have no time for swapping battery packs or personal hygiene.

Of course if you look at national averages, a different picture emerges. In the US, the average class 8 truck consumes 11,340 gallons of diesel per year at 6.011 mpg. That works out to just 220 gallons per week and 264 miles per day (assuming 5 days per week). Moreover, these miles spread out over an 8 hour work day is an average speed of 33 mph. Welcome to the exciting world of average trucking. So for the vast majority of trucks out there a 300-gal tank is simply a convenience so that they can fill up just once a week. Filling up is not a daily requirement anywhere near the average use case.

An electric truck that has 300 miles range will be quite adequate for average use, even without battery swapping and commercial Supercharging. So it's nice to know that perhaps half of the trucking market is addressable with little more than 500 to 800 kWh batteries and overnight charging. Supercharging and swapping are quite doable as well and are needed only to enhance the capabilities of the core product. That is a huge amount of upside growth potential while infrastructure gets rolled out and battery prices are driven down. Imagine just 10% of the trucking fleet going electric in five years. That would be huge for Tesla, but it would not even scratch the surface of the heroic extreme cases that so many are worked up about.

The world of average truck driving may not seem quite so adventurous, but that is the bulk of the market to be served.

 

[ggr]

Well, that made me have to look up the word "shibboleth."

If you look at folks expressing disbelief in electric trucks, they use jump to the most extreme uses cases, where teams of drivers take 40 tons thousands of mile across the outback with nothing so much as a piss brake to sustain them. So obviously they need 300 gallons to go 1200 miles at a shot and have no time for swapping battery packs or personal hygiene.

Of course if you look at national averages, a different picture emerges. In the US, the average class 8 truck consumes 11,340 gallons of diesel per year at 6.011 mpg. That works out to just 220 gallons per week and 264 miles per day (assuming 5 days per week). Moreover, these miles spread out over an 8 hour work day is an average speed of 33 mph. Welcome to the exciting world of average trucking. So for the vast majority of trucks out there a 300-gal tank is simply a convenience so that they can fill up just once a week. Filling up is not a daily requirement anywhere near the average use case.

An electric truck that has 300 miles range will be quite adequate for average use, even without battery swapping and commercial Supercharging. So it's nice to know that perhaps half of the trucking market is addressable with little more than 500 to 800 kWh batteries and overnight charging. Supercharging and swapping are quite doable as well and are needed only to enhance the capabilities of the core product. That is a huge amount of upside growth potential while infrastructure gets rolled out and battery prices are driven down. Imagine just 10% of the trucking fleet going electric in five years. That would be huge for Tesla, but it would not even scratch the surface of the heroic extreme cases that so many are worked up about.

The world of average truck driving may not seem quite so adventurous, but that is the bulk of the market to be served.

Of course if that's the average, and the distribution has a long tail, the median (arguably more important) is even less distance. Still, though, the variation on a daily basis will be very important, since the operator will want to be able to put in a full work day even on the more extreme days. That probably does still require about a 400 mile full charge range, assuming return-to-base for overnight charging. Definitely should be doable though, and does change the picture somewhat. I hope that Tesla has access to more detailed figures.

 

[AudubonB]

OT, but some time back a forum regular said he was keeping a list of my vocabulary words....

...abut just for your comment, I've changed my sig-line. Enjoy!

 

[jhm]

Of course if that's the average, and the distribution has a long tail, the median (arguably more important) is even less distance. Still, though, the variation on a daily basis will be very important, since the operator will want to be able to put in a full work day even on the more extreme days. That probably does still require about a 400 mile full charge range, assuming return-to-base for overnight charging. Definitely should be doable though, and does change the picture somewhat. I hope that Tesla has access to more detailed figures.

I would expect Tesla to market semis with different pack sizes, say 450, 650, and 900. So very quickly they'll get a read on what the industry is willing to pay for.

For trucking, I don't think it makes a lot of sense to buy a substantially bigger battery than is needed. For one thing, lugging around extra weight competes with how much you can haul. But most importantly its just not a good investment. If you're operating a fleet of trucks and only 10% are electric, you probably don't need those electrics to handle the longs possible routes. You simply want to be sure that your electrics are well utilized and saving the most money possible. The situation is very different if you are an independent operator with one truck. Then you want a truck that gives you flexibility. But in a large fleet, it is the diversity of the fleet that gives the flexibility, not the capability of the individual truck. Would you rather buy two 450s for $115k each or one 900 for $205k?

Of course, if you can swap into whatever battery size you need when you need it, then battery size at purchase is not so relevant.

 

[jhm]

Elon Musk: Tesla's semi-truck can be driven around 'like a sports car'

Musk said Tesla is looking to prove that an electric truck can outperform a diesel truck when it comes to range and torque even with the added weight of a battery.

"With the Tesla semi we want to show that an electric truck can out torque any diesel semi," he said.

I'm considering a career in trucking right now.

 

[kenliles]

Elon Musk: Tesla's semi-truck can be driven around 'like a sports car'



I'm considering a career in trucking right now.

Ha-- nice
I'm gonna outfit it completely, and live in one
King of the Road

 

[roblab]

Of course if that's the average, and the distribution has a long tail, the median (arguably more important) is even less distance. Still, though, the variation on a daily basis will be very important, since the operator will want to be able to put in a full work day even on the more extreme days. That probably does still require about a 400 mile full charge range, assuming return-to-base for overnight charging. Definitely should be doable though, and does change the picture somewhat. I hope that Tesla has access to more detailed figures.

Remembering my days as a trucker, our shop (we had one semi) used the truck once every couple weeks to drive maybe 200 miles and back. The rest of the time, it could have been plugged in. I suspect most tractors could be plugged in overnight for the short jaunts during the day. Where I worked, the fuel account was across town, so filling the tank fewer times (300 gal) was important.

There is nothing to compare charging where you park with driving somewhere to fill a tank.

 

[jhm]

Remembering my days as a trucker, our shop (we had one semi) used the truck once every couple weeks to drive maybe 200 miles and back. The rest of the time, it could have been plugged in. I suspect most tractors could be plugged in overnight for the short jaunts during the day. Where I worked, the fuel account was across town, so filling the tank fewer times (300 gal) was important.

There is nothing to compare charging where you park with driving somewhere to fill a tank.

It sounds like a truck sharing service would have been helpful too.

 

[Reciprocity]

It sounds like a truck sharing service would have been helpful too.

This is a given. That is why I hope Tesla doesn't sell a single Semi and instead builds a world class on demand logistics solution. As innovative as I expect the Tractor to be, I wonder what they have planned for the trailers and specifically in an on demand world, loads could be coming from more then one client on the same trailer, so there has to be a flexible way to load them.

 

[dhanson865]

Regen has its own issues as it can heat up the battery requiring the battery to cool more then requiring regen to disappear once it gets to hot. Regen would work pretty good otherwise and save a lot of wear and tear on the brakes. Maybe if the packs are separated and more independent, then you could pump a lot more regen into them. I am wondering if they will have a transmission instead of a single gear motor.

Trucks have more than one axle ignoring the trailer. They could easily have 2 or 3 motors (one per axle) each with a single gear just like Model S/X with two motors has each at a slightly different gear ratio.

When you look at an 18 wheeler that middle set of double wheels that looks like it is at the front of the trailer is actually part of the rig that pulls the trailer, the trailer has no front wheels.

notice not only is there two rear axles but there is basically a skateboard line under the cab very similar in concept to the Tesla pack/motor setup.

 

[jhm]

Trucks have more than one axle ignoring the trailer. They could easily have 2 or 3 motors (one per axle) each with a single gear just like Model S/X with two motors has each at a slightly different gear ratio.

When you look at an 18 wheeler that middle set of double wheels that looks like it is at the front of the trailer is actually part of the rig that pulls the trailer, the trailer has no front wheels.

notice not only is there two rear axles but there is basically a skateboard line under the cab very similar in concept to the Tesla pack/motor setup.

To trucks conventionally have drive to both rear axels? How about front wheels? Would there be much advantage to all wheel drive?

Musk has said that the Tesla will out torque any semi truck out there. I suspect that would include AWD, though traction and torque are two separate issues. It seems that truck operators would appreciate both. Superb traction could improve safety especial in poor weather conditions. Being able to accelerate and climb hills quickly could cut travel times.

Musk also said the Tesla's range would exceed diesel trucks. I'm having a hard time wrapping my head around that. 300 gal at 6 mpg is a 1800 mile range. So are we talking about a 3.6 MWh battery? I'm not even sure why that much range would even be desirable. Charging once or twice a day seems sufficient. Having enough range to charge only once or twice per week seems overkill.

So I look forward to the September unveiling. I suspect that Tesla will come out with an extremely over built performance version just to break down anti-EV misconceptions. It will be the baddest rig on the road. But most operators will be quite happy to save money on a more economical version.

 

[dhanson865]

Do trucks conventionally have drive to both rear axels? How about front wheels? Would there be much advantage to all wheel drive?

6×4 (drivetrain) - Wikipedia

A 6×4 drivetrain (six-by-four) is a vehicle with a drivetrain of three axles delivering power to two wheel ends on two of them.[1] It is a form of four-wheel drive[2] but not one of all-wheel drive.

It is the most common form of drivetrain of semi-tractors[2] and heavy haul fixed-chassis cargo trucks.

I think the drive train pictured is of the type described above but I pulled it from a random google search. I'd say the two rear most axles are being driven and the front wheels are steering and brakes only (I'd assume brakes on all 3 axles)

You know they'll fill the driveshaft area with battery pack modules.

I'd argue they wouldn't want to drive two axles from one motor so they'll be forced to use two motors minimum just to avoid adding another drive shaft.

The advantage Tesla could have of driving all 3 axles instead of just two is an additional gear ratio given they will be using fixed gear ratios and no transmission. But they could as easily do two motors with only two of the axles and not go for the 3rd motor.

Essentially the extra motor(s) could kick in as needed with the "torque sleep" behavior that extends range.

 

[jhm]

6×4 (drivetrain) - Wikipedia

I think the drive train pictured is of the type described above but I pulled it from a random google search. I'd say the two rear most axles are being driven and the front wheels are steering and brakes only (I'd assume brakes on all 3 axles)

You know they'll fill the driveshaft area with battery pack modules.

I'd argue they wouldn't want to drive two axles from one motor so they'll be forced to use two motors minimum just to avoid adding another drive shaft.

The advantage Tesla could have of driving all 3 axles instead of just two is an additional gear ratio given they will be using fixed gear ratios and no transmission. But they could as easily do two motors with only two of the axles and not go for the 3rd motor.

Essentially the extra motor(s) could kick in as needed with the "torque sleep" behavior that extends range.

Thanks for digging into this. My impression is that they will use at least 3 motors. Replacing a $75k drivetrain, adding extra motors is a fairly small cost by comparison. So they may as well exploit the affordability of this natural advantage.

So let's imagine what the Performance version could look like. Volvo has a hand-built truck with 2400 hp (Volvo's 2,400-hp semi is the quickest truck in the world). But 2000hp may be number to beat. So the Model S P100D has 680hp net from 259hp front and 503hp back. So the performance version is need more than 3X the power. I would expect that Tesla can build bigger motors, but an interesting option may simply to use six 503hp motors. That would provide up to 3018hp gross. So maybe 2800hp net. These motors may need about 2250kW, and a 400kWh battery may suffice, though I'd expect a much bigger battery for the performance version.

The Volvo dream truck has 4425 lb-ft torque. I suspect that with six 503hp electric motors there is some way to set gear ratios to deliver that much torque.

So this little fantasy is merely an obvious starting point for Tesla. They can take 503hp motors off the shelf, but I suspect they can do much better optimization than that. Coordinating six motors could be more of a software challenge. But I think it could be enormously impressive. Six motors could deliver very impressive traction. It could also be quite useful when tires blow or other mechanical failures happen.

I'm pretty eager to see what they come up with.

 

[dhanson865]

So the Model S P100D has 680hp net from 259hp front and 503hp back. So the performance version is need more than 3X the power. I would expect that Tesla can build bigger motors, but an interesting option may simply to use six 503hp motors. That would provide up to 3018hp gross. So maybe 2800hp net. These motors may need about 2250kW, and a 400kWh battery may suffice, though I'd expect a much bigger battery for the performance version.

The Volvo dream truck has 4425 lb-ft torque. I suspect that with six 503hp electric motors there is some way to set gear ratios to deliver that much torque.

Take a look at Semi Truck Engines | Mack Trucks 1,500 lb-ft of torque is mid range. That 4,425 lb-ft torque is off the charts.

The P100D does 864 lb-ft of torque on a dyno. 3 of those would be 2,592 lb-ft which is still off the charts vs the best powertrain on the macktrucks list.

Elon has stated repeatedly that they won't do more than one motor per axle for cars. I'm going to say this applies to trucks as well.

The limit on HP is based on the battery pack (volts), fuse (amps), inverter (easily not the overall limiting factor). The motor could do more Net HP if the other parts can keep up.


I'd expect something like one of these:

* 3 x the largest motor available for the S/X
* 2 x a new larger motor + one mid sized motor
* 2 x a new larger motor
* 2 x the largest motor available for the S/X (for a base trim, puts it in line with a standard semi tractor torque)

I don't know that they'll do the whole P trim for the semi. I don't know if they will offer multiple engine options. Maybe the engines are a given and the battery pack/fuse is all that changes.

 

[neroden]

Sooo.... I'm going to take a wild guess here and bet that we'll see an "extended cab". For the following reasons:
(1) room for aerodynamics (less of a flat striking surface of air in the front, means longer nose)
(2) the longer the tractor the more room for more battery

 

[bxr140]

Sooo.... I'm going to take a wild guess here and bet that we'll see an "extended cab". For the following reasons:
(1) room for aerodynamics (less of a flat striking surface of air in the front, means longer nose)

And sort of A380-like, the driver will sit lower than intuitive. Probably more the height of a typical pickup.

 

[Pando]

Tesla Semi: New Image, and Everything We Know -- The Motley Fool

Not sure if this has been posted yet (edit: it has, above. Sorry)

 

[Pando]

Elon Musk: Tesla's semi-truck can be driven around 'like a sports car'

Ugh. Imagine trying to pass a semi on a highway and it keeps up with you. Performance on a semi is nice, but it can easily be abused and will be intimidating to everybody around.