Lets work out the Tesla Semi-Truck Technical Specs

[Farmertom]

Thing is, if the loads in question are divisible, like foodstuffs, appliances, materials, (and not a product designed to absolute weight limit, like a turbine genset optimised to the lowest unladen weights) there's an easy way around that issue.

Apparently loads of beer are not divisible, I had a heavy truck and my prep for the next load was to be ready with full fuel if I had time. I went to load my option was to take the set weight or leave it. I chose to take it, I was 2500lb over gross legal weight for the US, it was my lucky day, all five scales enroute the Canadian border were closed. I was legal for Canada.

Yes, I know they will adjust weights if and when heavy trucks become mainstream.

 

[EfficientWatts]

Kind of late to join here...

Around charging at depots, for north america there's a standard evolving to support 3-phase charging with a standard plug that's targeted at larger EVs like trucks and buses

J3068 - 3 Phase A/C Charging for North America

Whether Tesla will support this standard or not remains to be seen. I cannot see them getting away with a standard Tesla wall connector as it will take too long for an overnight charge, unless they force the usage of DCFC at the depots. They could have their own proprietary connector for faster 3-phase A/C charging, but then they might as well use the European connector instead of designing another one from scratch (though I wouldn't put it past them to do this).

As for the existing plug itself keep in mind this is a prototype so I do not think that would be how the final connector will look like.

 

[arnis]

• Expected Base Price (300 mile range)
  $150,000
• Expected Base Price (500 mile range)
  $180,000

Therefore 100 miles of battery costs $15 000.
Therefore 500 mile battery costs $75 000.
Therefore kWh price is around 75000/800 = $94/kWh

I would actually assume 300 mile version costs slightly more
per kWh compared to 500 mile version. So actual price could
be something like 140 000 vs 180 000. Plus definitely there is
some cost hidden in battery pack skeleton (coolant loop, case,
connections, busbars). So rather 1kWh costs around $125.
Cost per kWh should be between $105-135 with high probability.
aka hardcore smackdown to other battery manufacturers.

 

[mongo]

So what is the real kWh/ mile?

Coefficient of drag is 0.36
Max cross section for a semi is 14 ft tall by 8.5 ft wide.
At 60 MPH, that calcs to 62.2 HP, or 46.4 kW. So 0.773 kWh/ mile to move through air.
If the system is only 8 ft wide, and the height is really 13.5 ft (Michigan limit).Then it's down to 0.70 kWh/mile. Carve out the area below the tractor between the wheels say 6 ft^2 and we're at 0.66 kWh/ mile .

Next major factor, tire rolling resistance.
Given axle weights of 13k front, 34k tractor tandem, 34k trailer tandem, an EPA report and a Michelin comparison site. I get 50.47 kW or 0.74 kWh/mile.

Together, that gets us to 1.51 kWh/mile for the large frontal area and 1.4kWh/mile for lower area. Add in a heater, lights, mechanical losses and we're somewhere in the 1.6 kWh/mile range.

So 800 kWh to get 500 miles of range and 640 kWh for the 400 mile 30 minute recharge @ 1.28 MW rate (10 supercharger equivalent).

Would like others to see what others get for rolling resistance.

 

[JKolodziejski]

So what is the real kWh/ mile?

Coefficient of drag is 0.36
Max cross section for a semi is 14 ft tall by 8.5 ft wide.
At 60 MPH, that calcs to 62.2 HP, or 46.4 kW. So 0.773 kWh/ mile to move through air.
If the system is only 8 ft wide, and the height is really 13.5 ft (Michigan limit).Then it's down to 0.70 kWh/mile. Carve out the area below the tractor between the wheels say 6 ft^2 and we're at 0.66 kWh/ mile .

Next major factor, tire rolling resistance.
Given axle weights of 13k front, 34k tractor tandem, 34k trailer tandem, an EPA report and a Michelin comparison site. I get 50.47 kW or 0.74 kWh/mile.

Together, that gets us to 1.51 kWh/mile for the large frontal area and 1.4kWh/mile for lower area. Add in a heater, lights, mechanical losses and we're somewhere in the 1.6 kWh/mile range.

So 800 kWh to get 500 miles of range and 640 kWh for the 400 mile 30 minute recharge @ 1.28 MW rate (10 supercharger equivalent).

Would like others to see what others get for rolling resistance.

Astonishingly similar to the results I extrapolated earlier by geometry. However I'm still skeptical that it can do exactly 80% in 30 minutes.

I think from 10% to slightly over 55% is more realistic for NCA/NCM.

 

[oneday]

This is a video of Jerome in the Netherlands.

Two things of note, Semi will be used by Tesla from Fremont and the gigafactory before any sales to customer. And the Semi is designed to have the same gross hauling capacity as compribable diesel semi’s. That answers one of the big questions speculated here.

 

[JKolodziejski]

@mongo

@arnis

Found this link on Reddit's Tesla Motors subreddit (terrible place...) Seems to be more analytical evidence that the Semi is indeed closer to 1.5 kWh/mile than 1.75 - 2. It is best-case though.

Tesla Semi is reasonable, part 1 | Selenian Boondocks

Come to think of it, an efficiency just above 1.5 kWh/mile is a good explanation for why Tesla advertised "<2kWh" as there may be just enough improvement in the future to eventually reach across this 0.5 threshold and call it "1.5 kWh" instead.

 

[mongo]

@mongo

@arnis

Found this link on Reddit's Tesla Motors subreddit (terrible place...) Seems to be more analytical evidence that the Semi is indeed closer to 1.5 kWh/mile than 1.75 - 2. It is best-case though.

Tesla Semi is reasonable, part 1 | Selenian Boondocks

Come to think of it, an efficiency just above 1.5 kWh/mile is a good explanation for why Tesla advertised "<2kWh" as there may be just enough improvement in the future to eventually reach across this 0.5 threshold and call it "1.5 kWh" instead.

Yah, just watch out that the aero number is off by a factor of two in the body of the blog. I agree with the 1.5kWh in spring/ fall best case (maybe drag is better than 0.36....). If the tractor comes in under 20k pounds, that will help too.

 

[electracity]

I hope they can get trucks running between Sparks and Fremont before the factory is finished. Imagine actual beta vehicles from Tesla. That would be so......normal.

 

[AudubonB]

Leaving aside the sarcasm with which your posts normally drip, why do you write "...can get running..." rather than make the supremely more logical supposition that that is exactly what has been happening for the past eleven months?

 

[Cloxxki]

Astonishingly similar to the results I extrapolated earlier by geometry. However I'm still skeptical that it can do exactly 80% in 30 minutes.

I think from 10% to slightly over 55% is more realistic for NCA/NCM.

Don't forget, it's Tesla we're talking about. I didn't hear 80% in the presentations, I heard 400 miles. They are not the same necessarily.
The 500 miles is based on 60mph, full load, worst case, right?
Charging in Tesla terms goes by typicalrange unless explicitly specified otherwise. The "typical" range of a Semi, using so much regen, optional drafting in convoy, lower speeds due to speed limits, being half loaded on average, etc, etc, could well end up below 1kWh/mi. Or, imagine an EPA cycle (if such exists for trucks) where the acceleration is as slow as a similar diesel powered one. Adding 400 of those miles could mean just 400kW.
But hye, 2019 would not be a bad moment (kind of late) for Tesla to join today's reality off charging speeds. No all other brands, even low cost ones, use cells as slow as Tesla's. Slowness has been their choice, overcome by having the largest packs, made viable by sticking them into quite luxury high priced cars. Like for like, they're slow cells. If Tesla were to outsource batteries to LG, getting such charge speeds would not be a problem. Just build the pack, and build the charger. With today's Power Pack cells, it doesn't really seem to be on the cards. Unless maybe you use my little calculation, going back to typical range raher than worst case range in the case of recharging.

Someone posed that perhaps the Roadster is over-charged to get 200kWh. Could the Semi get 500 miles worst case by being overcharged? Seems unlikely. If that can be done reliably, it's no longer overcharging.

 

[WannabeOwner]

I'm still skeptical that it can do exactly 80% in 30 minutes

I expect I'm missing something, but what is it that makes you sceptical?

I think I'm right in saying that all the MS / MX models do 80% in 30-ish minutes, after that the taper is significant.

Assuming enough power and that the cells can be charged in a balanced manner, doesn't that suggest that even a 1,000 kWh battery can be charged 80% in 30 minutes?

 

[mongo]

Did a little dimensioning in Paint today.

From the Tesla Twitter video, The 5th wheel is basically directly over the fore rear axle. This means the air suspension can lift the trailer using this axle to the max legal of 20k pounds without impacting the load distribution of the other two axles.

So, base numbers (pixels)
Front axle 0
Fore rear axle 669
Aft rear axle 891
Battery pack center line: 313
Pack weight 8,000 lbs (800 kWh pack 39k cells @ 66 grams each +2,300 lbs structure)
Drive axle weight 2,000 lbs (including motor/inverter/ tires structure)
Trailer 5th wheel weight at 5th wheel 25k lbs (based on 34k max for tandem - 9k typical tractor weight)
Frame weight on front axle 4k lbs (not including battery,includes front suspension and tires)
Frame weight on aft rear axle 3k lbs (not including battery, axles)

Gives a weight distribution of (in pounds)
Front: 11,700
Fore rear: 17,000
Aft rear: 15,300

So there is still 1,700 of motor/axle weight available.

No idea what a normal truck weighs (engine, trans, and 100 gallon of fuel seem to be around 4k), so some numbers may be off, but Tesla's goal of matching diesel capacity seems feasible.

 

[electracity]

Leaving aside the sarcasm with which your posts normally drip, why do you write "...can get running..." rather than make the supremely more logical supposition that that is exactly what has been happening for the past eleven months?

You really miss being an alpha dog moderator, don't you?

What a glorious month you had!

 

[AudubonB]

....a certain poster will be off for ten days.

 

[scottf200]

Apologize if this was shown already. Saw it in a presentation here: Tesla’s VP of Trucks talks about new electric semi, weight, charging, and more

Drivers log on left and Thermal display on right. Obviously I zoomed in so some things are blurry. Wonder if the thermal display is for diagnostics and not part of the normal user interface.

Semi display from video above:

Car - Tesla Model X/S display:

 

[mongo]

Apologize if this was shown already. Saw it in a presentation here: Tesla’s VP of Trucks talks about new electric semi, weight, charging, and more

Drivers log on left and Thermal display on right. Obviously I zoomed in so some things are blurry. Wonder if the thermal display is for diagnostics and not part of the normal user interface.

Semi display from video above:

Car - Tesla Model X/S display:

Well, assuming that is an accurate layout of the tractor cooling system, and not just a modified S system, I wonder if the 8 pin charger feeds 2 sets of Delta+Ground to the two chargers in AC mode? On second thought, maybe not since UL doesn't like having switches in ground circuits...
But going with it anyway:
Superchargers run at 480V Delta, so that would provide 250kW per feed at 300 Amps. 500kW for the pair (Or I messed up the power calculator). If the sub packs normally take 320kW each, this would provide a 90 minute 400 mile charge.
But I would guess the real on board charge rate is much lower.

 

[arnis]

This thermal screen likely is just for demonstration.
Semi can't have it exactly like that.
There are 4 stand-alone drivetrains. Can't cool all that with one fluid pump.
There is no reason to have two condensers of AC and one glycol radiator, like S has.

 

[juanmedina]

Little frustrating to see that so many are still assuming the truck has as much as one megawatt hour. For cost reasons the Semi isn't likely to use anything other than 2170 cells (in production at least), and I am sure it's not physically possible to have more than 800-850kWh from the geometrical analysis I did earlier in the thread. Have a look at it.

Can send Solidworks files if anyone cares, but this site doesn't allow ".sldprt"

Put the files in grabCAD.

I can't believe the Tesla semi cost so little. Do you guys think they are loosing money on every truck and the are just doing it to kill the competition?

 

[jkn]

How many trucks are manufactured yearly? No matter what they do, they cannot kill competition in next 10 years. Perhaps small developers have now difficulties to get development money, but large companies have increased their efforts.