Tesla Semi Truck

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RegGuheert said:
Here is some more discussion on the LOADED energy estimated to get the Tesla Semi from Fremont to the top of Donner Pass:
InsideEVs said:
Our modeling shows that the kWh burn to get to the top of Donner Pass is 587 kWh’s.
Also
InsideEVs said:
According to an ongoing thread at Tesla Motors Club, the drivers have said that the trucks are both 300-mile range versions.
But I'm wondering if they contain 400-V batteries or 800-V batteries. My guess is 400-V batteries OR they have a DC-DC converter included just for charging from Superchargers.

Off to read the thread mentioned discussing this subject.
 
RegGuheert said:
See http://www.mynissanleaf.com/viewtopic.php?f=10&t=24551&start=180#p521210

Again, where is a base range analysis of a EV semi full loaded traveling at 60 mph on level terrain, i.e. assuming the same load
capacity as a diesel semi? It's not difficult!
 
lorenfb said:
RegGuheert said:
See http://www.mynissanleaf.com/viewtopic.php?f=10&t=24551&start=180#p521210
Again, where is a base range analysis of a EV semi full loaded traveling at 60 mph on level terrain, i.e. assuming the same load
capacity as a diesel semi? It's not difficult!
Who said anything about level ground? I estimated that and unloaded trip from the Gigafactory to Fremont would consume about 300 kWh based on a simulation result that said the trip would take about 378 kWh when fully loaded.
 
RegGuheert said:
lorenfb said:
RegGuheert said:
See http://www.mynissanleaf.com/viewtopic.php?f=10&t=24551&start=180#p521210
Again, where is a base range analysis of a EV semi full loaded traveling at 60 mph on level terrain, i.e. assuming the same load
capacity as a diesel semi? It's not difficult!
Who said anything about level ground? I estimated that and unloaded trip from the Gigafactory to Fremont would consume about 300 kWh based on a simulation result that said the trip would take about 378 kWh when fully loaded.

So you weren't specific on what you meant. O.K., I miss interrupted you. Again, can you answer my question? I couldn't care less about
Elon's battery transport stunt!
 
RegGuheert said:
GRA said:
I didn't see any mention of Megachargers in the article, but I just skimmed it. Was that mentioned?
I surmised that from the fact that they drove the trucks both ways. I had thought that is the only charger available for these trucks. But it seems that at least *some* of the prototypes can be charged using Superchargers, including one of the trucks used in this demonstration<snip>
Thanks.

RegGuheert said:
GRA said:
Reg, like most northern CA skiers I've made the drive (both ways) many times, so I'm well aware of the elevation changes.
Yeah, that's why I called you out on characterizing this trip as "downhill".
Well, it largely is, but there is that climb at the start. It's certainly more sensible to call the westbound trip downhill than it does the eastbound one; the truck climbing lanes are eastbound!

RegGuheert said:
GRA said:
The packs should fit in a container no problem (internal width about 7'8" IIRR, although whether or not the packs can be loaded lengthwise side-by-side may be a problem), the issue will be do they have to transport special racks up the hill to stack them, if so do they fold, and what do the racks weigh? I've used (non-folding) racks similar to the one on the right end of the upper gallery row here: https://tier-rack.com/application/shipping-racks.html (the picture just left of that shows the same rack folded), but there's no way they could handle the weight of a battery pack, even if putting that much weight that high up were acceptable. A battery pack could use a much lower, stronger rack. As battery packs are dense commodities maybe stacking won't be required, and using regular dunnage (plywood, foam, pallets, inflatable bags) and shipping them in a single layer will be okay.

The other option, and one that may make sense is to haul the containers to the Livermore warehouse or else a trans-shipment warehouse at the Port (in my Teamster casual days I sometimes worked at one), and consolidate 40' container loads into 48' or 53' trailers before hauling them up the hill. It will probably depend on whether or not trailers fully loaded with packs are weight critical and can't be fully loaded in any case.
Thanks, I considered that the batteries will need racking (I'm willing to bet that they do), but I hadn't thought about getting them back up the hill. Perhaps those can be transported back up with many of them in a single load.
Either can be done. It helps if they fold or are designed to stack, as it makes it possible to load them on top of other freight in rear of a container when there's room, but transshipping allows you to use them both directions. Still, there were times when there was an excess of racks on our dock and some other terminal needed them, and we'd shove a bunch of them into an empty or nearly empty trailer. Deadheading is to be avoided, but needs must. If time allowed and we were tight on space we might flip every other one upside down so we could stack them, but that shouldn't be necessary with lower battery racks.

Thinking about it, I'm pretty certain that the packs can't be loaded side by side on the floor, so racks would almost certainly be required. Does anyone have any dimensional specs on any of the Tesla packs?

RegGuheert said:
GRA said:
It's a pity they weren't able to do this kind of baseline run earlier so that they could get a bad winter weather test in, because there's a good chance that they'll now have to wait until next winter for similar conditions.
You're kidding, right? I think it would be extremely foolish to make early test runs in poor weather for a large number of reasons.
Which is why I said it would have been nice if they'd made some baseline runs earlier in good weather to work out some of the early bugs, before they attempted it in bad. Hot weather testing will largely be about how components hold up to heat, while cold weather will mainly be about range. As I guesstimated and the IEVS article you quoted calculated, the 300 mile packs probably can't make the eastbound trip fully loaded even when new. I've always thought this trip would need the 500 mile packs.
 
RegGuheert said:
we are discussing hauling batteries from the Gigafactory to Fremont.

Like I said, who really cares about another Elon publicity stunt! But here's back to reality, which this thread seems to neglect:

Using previously calculated theoretical data and assuming a fully loaded EV semi versus a diesel semi for a trip from SpaceX (SoCal)
to Tesla Fremont (NoCal), the following best case analyses result:

I. Assumed Data
a. Route - U.S. 5 (no GrapeVine/mountains, no major grades - unrealistic )
b. Distance - 350 miles (assume 400 miles for margin)
c. Range for EV semi per previous posted calcs - .40 miles/kWh
d. Battery weight - equals original diesel drive-train (unrealistic as noted below)
e. Battery size - equals original diesel drive-train (unrealistic as noted below)
f. Speed - 60 mph
g. No charging on route needed
h. EV semi requires no additional axles (???)

II. Analysis - EV Semi

1. Required battery capacity; 400 miles / .40 miles/kWh = 1000 kWh
2. Battery weight based on using MS (1200 lbs -14 lbs/ kWh) = 14, 000 lbs
3. Present market battery cost per kWh of $100 (Panasonic discount) = $100K
4. Trip cost mile for energy ($.10 per kWh) = $100

III. Analysis - Diesel Semi

1. Required fuel @ 7.2. miles/gal ~ 60 gallons
2. Diesel fuel costs - $4.00 / gallon
3. Trip cost = $240 (cost per mile $.60)
4. Diesel engine cost (Cummins) - $10K
5. Trans & diff cost - $10K

IV. Major Key Issues for EV Semi
1. Amortization period required for battery costs
2. Significant additional overall weight/size/location requirements for battery
3. When in the future a TCO economic parity occurs relative to a diesel semi
4. Assumptions for charging infrastructure costs & build-out time
5. Optimum battery capacity versus charging time versus infrastructure versus addition driver layover (charging) costs
 
If Tesla is really serious about producing a EV semi in the near term, they should build two test tractors capable
of pulling a vehicle transporter loaded with seven Tesla vehicles being transferred from Fremont to the L.A. area,
by mid 2018. From what I've seen over the last 2-3 years, Tesla makes at least two deliveries per week to the L.A. area.
Initially from a battery energy perspective, a range of only about 150 miles would be necessary traveling the 101 Hwy,
thus avoiding the GrapeVine and Hwy 152 via Hwy 5. Besides, the availability of SCs is greater along the 101 Hwy,
resulting in an initial smaller battery. The data gathered would not only further corroborate the design concept and
technology, but additionally it would greatly enhance Tesla's PR with regard a EV semi.
 
Found some guesstimates of the Model S pack size. It's stated that the batteries are located inside the wheels (F to R), and as the wheelbase is 116.5" and the width 77.3", one size guesstimate I found was about 112" x 70" (9'4" x 5'10"). Height of the main part of the pack is only about 5" though. As these dimensions are too wide to put side by side or to be loaded crosswise, if Tesla wants to ship complete battery packs from the Gigafactory they'll definitely have to stack them to get anywhere close to gross weight, presumably using racks to avoid damage. The Model 3 pack is presumably a bit shorter but the wheelbase has only dropped to 113.2", so the likelihood that a complete Model 3 pack will fit crosswise in even a wide-body trailer (102" ext. width, but about 98" internal) seems minimal. I found weight and cube for the LR pack, 1,058 lb. and 14.13 ft.^3.

I think in order to maximize cube as well as gross, and also keep the C.G. down, it might be better to ship battery components rather than complete packs and do final assembly in Fremont, but I expect Tesla will look at costs both ways and decide which makes the most sense. Either way, even at only 1,000 Model 3s/week production and stacking packs 10 high (unlikely for C.G. reasons) so they could theoretically put up to 40 in a 40' container, that's 25 round trips/week.
 
This excellent post at Tesla Motors Club makes a fairly careful estimate of the capacity of the Tesla Semi battery:
Kolodziejski at Tesla Motors Club said:
I think this strongly suggests a usable of 800kWh, with a megawatt hour being impossible with the same chemistry as the Model 3.
But I will point out that if Tesla can manage to stabilize the NMC chemistry in the batteries used in the Model 3 for operation at higher voltages, 1 MWh should be quite achievable without adding any more cells.
 
lorenfb said:
RegGuheert said:
That's a good question, but even fully unloaded, this trip likely required the consumption of at least 300 kWh and traveled over 250 miles.

Where are the data to conclude this, i.e. an energy consumption of at least 300 kWh (over 250 miles) - less than a mile/kWh?

Elon Musk has stated that the Semi would beat 2kWh per mile, and certainly 300kWh over 250 miles is that. I suspect is far closer to 500kWh for the trip.
 
FWIW, Nikola estimates efficiency to be 0.58 mi/kWh (1.72 kWh/mi) (at 22:45 in the video):

[youtube]http://www.youtube.com/watch?v=Bt6r7of5qA0[/youtube]

Other electric truck manufacturers come up with efficiencies between 1.4 kWh/mi and 2.0 kWh/mi based on unknown assumptions:
JKolodziejski at Tesla Motors Club said:
Daimler E-FUSO Vision One (slightly streamlined, flat face, 11 tonne payload) => 300 kWh / 220 miles = 1.4 kWh/mile.

Daimler unveils heavy-duty all-electric truck concept with ‘up to 220 miles’ range

Cummins AEOS (34 tonnes overall, 75k lbs, Class 7 (drayage?) ) => 140 kWh / 100 miles = 1.4 kWh/ mile.

Besting Tesla's Reveal By Just Days, Cummins Unveils AEOS Electric Semi

BYD Class 8 (Cheap, Chinese-made conventional flat-face truck) => 188 kWh / 94 miles => 2.0 kWh / mile exact.

http://www.byd.com/usa/wp-content/uploads/2016/08/T9-final.pdf


Freightliner Supertruck (65k lbs, most similar use case and possibly similar all-length drag efficiency to the Tesla Semi.)

https://www.trucks.com/2015/06/25/freightliner-supertruck-is-super-efficient/

=> 48-52% thermal efficiency, 12.2 US-mpg, => 3.22 miles / L or per 10.8 kWh(th) @ 0.48 to 0.52 = > ~ 3.22 miles / 5.2-5.6 kWh mech.
=> (5.2 to 5.6) kWh / 3.22 miles = 1.61 to 1.73 kWh / mile after engine.

... and a 92% efficient battery power equivalent to "48-52% efficient 12.2 US-mpg Freightliner Supertruck" = 1.61 to 1.73 / 0.92 = 1.75 to 1.88 kWh / mile.


And this.

Tesla Semi is reasonable, part 1 | Selenian Boondocks

"<2 kWh" was stated for a reason.

1.5 to 1.7 kWh per mile at 56-65 mph is realistic.
 
lorenfb said:
1. What is the generally accepted typical energy usage per mile (miles/gal) for a diesel rig (tractor & typical fully loaded trailer)
traveling at 60mph on a level highway?
2. What is the assumed miles per kWh for the semi in #1, given these components;
a. Rolling Resistance Losses - RR = k * V
b. Drag Losses - DL = k * V^3
c. Energy Conversion Efficiency of the diesel ICE, - assumed to be a little better than a gasoline ICEV (@ about 60%), assume 75% for diesel?
3. What is the assumed miles per kWh for an EV semi assuming RR & DL are the same for a diesel ICE semi traveling under the same
conditions and assuming about +95% energy conversion efficiency for the EV semi?

A simple solution to #3;
1. Assume 38 kWh per gallon of diesel fuel.
2. Assume RR + DL = energy output of diesel = .75 of diesel fuel energy input
3. Then miles/kWh for the EV semi = miles/gal (diesel mileage) X (EV conversion efficiency) / (kWh/gal X diesel conversion efficiency),
or simply MPG (#1) X .95 / (38 X .75)
4. Assuming a diesel ICE under conditions of #1 with an MPG = 5 miles/gal (bad assumption?) then;
EV semi miles/kWh = .167 miles/kWh
5. If one assumes that the diesel is only 50% efficient versus 75%, then the EV semi miles/kWh becomes .5 miles/kWh

Using an EV efficiency of 98% and a nominal 7 miles/gal for the diesel, the result becomes; .72 miles/kWh (1.38 kWh/mile)

Theory makes for a great starting point, but it's time for Tesla to do actual long term field testing:

lorenfb said:
If Tesla is really serious about producing a EV semi in the near term, they should build two test tractors capable
of pulling a vehicle transporter loaded with seven Tesla vehicles being transferred from Fremont to the L.A. area,
by mid 2018. From what I've seen over the last 2-3 years, Tesla makes at least two deliveries per week to the L.A. area.
Initially from a battery energy perspective, a range of only about 150 miles would be necessary traveling the 101 Hwy,
thus avoiding the GrapeVine and Hwy 152 via Hwy 5. Besides, the availability of SCs is greater along the 101 Hwy,
resulting in an initial smaller battery. The data gathered would not only further corroborate the design concept and
technology, but additionally it would greatly enhance Tesla's PR with regard a EV semi.
 
lorenfb said:
Theory makes for a great starting point, but it's time for Tesla to do actual long term field testing:
Tesla and the other companies have actually measured the energy use of their trucks. You are the one who is stuck on theory and the odd man out with 2.5 kWh/mi.
 
RegGuheert said:
lorenfb said:
Theory makes for a great starting point, but it's time for Tesla to do actual long term field testing:
Tesla and the other companies have actually measured the energy use of their trucks. You are the one who is stuck on theory and the odd man out with 2.5 kWh/mi.

No, not really! What was presented was a first order approximation, i.e. based on simple H.S. physics, which was lacking in the thread.
Each is free to use different assumptions. Surprised that you didn't present some simple analysis other than what usually gets presented,
i.e. a copy & paste. The approximation obviously didn't include mods to the losses, i.e. rolling resistance and Elon's "tweaking" of the drag
coefficient. Again, without any rigorous worst case field testing, i.e. thousands of miles over various terrains, the Tesla EV semi
projections are marginal at best and this thread "goes nowhere fast".
 
lorenfb said:
No, not really! What was presented was a first order approximation, i.e. based on simple H.S. physics, which was lacking in the thread.
And your H.S. physics causes you to come up with this:
lorenfb said:
Did you overlook this:
Using an EV efficiency of 98% and a nominal 7 miles/gal for the diesel, the result becomes; .72 miles/kWh (1.38 kWh/mile)
Let's correct your math to eliminate the confusion you are trying to spread:

7 mi/gal * 2 gal(in)/gal(out) * 1/38 gal/kWh = 0.37 mi/kWh = 2.7 kWh/mi

This result seems pretty clear: After throwing away 50% of the energy content of the diesel in the tank, these trucks achieve low efficiency due to their inability to recover some of the potential energy gained in climbing hills. They are also losing some of their energy to poor aerodynamics.
 
RegGuheert said:
lorenfb said:
No, not really! What was presented was a first order approximation, i.e. based on simple H.S. physics, which was lacking in the thread.
And your H.S. physics causes you to come up with this:
lorenfb said:
Did you overlook this:
Using an EV efficiency of 98% and a nominal 7 miles/gal for the diesel, the result becomes; .72 miles/kWh (1.38 kWh/mile)
Let's correct your math to eliminate the confusion you are trying to spread:

7 mi/gal * 2 gal(in)/gal(out) * 1/38 gal/kWh = 0.37 mi/kWh = 2.7 kWh/mi.

Yes, a simple math error, but the original relationship was correct. To help you with the units in your expression, my initial expression;

3. Then miles/kWh for the EV semi = miles/gal (diesel mileage) X (EV conversion efficiency) / (kWh/gal X diesel conversion efficiency),

Have you forgotten Tesla's estimate per your quote;
Tesla Semi webpage wrote: <2 kWh/mi

Then my assumptions weren't that far off when the math error was corrected (2.7 kWh/mi), right? As I said previously:

Each is free to use different assumptions. The approximation obviously didn't include mods to the losses, i.e. rolling resistance
and Elon's "tweaking" of the drag coefficient.

RegGuheert said:
This result seems pretty clear: After throwing away 50% of the energy content of the diesel in the tank, these trucks achieve low efficiency due to their inability to recover some of the potential energy gained in climbing hills. They are also losing some of their energy to poor aerodynamics.

So you just realized that? And it took a simple H.S. physics equation to get you thinking in those terms after all those posts in this thread?
I'm really disappointed!
 
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