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Tesla Class 8 Semi Truck Thoughts

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AWDtsla

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Mar 3, 2013
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#1
TonyWilliams said:
My calculations for EV truck energy consumption are based one gallon of diesel #2 is 38kWh, so using 7mpg = 5.4kWh of diesel energy per mile. If we assume that is 45% efficient, and electricity is 85% efficient from the grid to the truck, plus truck consumption, then 2.86kWh of electricity is required per mile, or 0.35mile/kWh.
Click to expand...

Cummins has been aiming for 55% thermal efficiency. If you take wintertime travel into account, the thermal efficiency increases further as waste heat heats the cab, no idea how much but I suspect it's significant.

I suspect a Tesla truck will need to make significant improvements in drag to compete at all.
 
#4
AWDtsla said:
Cummins has been aiming for 55% thermal efficiency. If you take wintertime travel into account, the thermal efficiency increases further as waste heat heats the cab, no idea how much but I suspect it's significant.

I suspect a Tesla truck will need to make significant improvements in drag to compete at all.
Click to expand...

With a truck that has 1MWh of batteries (ten S-100D batteries... well over 5 tons of batteries) that is required to make the Class 8 truck go 333 miles, I suspect cabin heating is an afterthought. Heck, they could use a simple heater that burns diesel, that every truck stop will have. It can supplement battery heating, too. It doesn't need to be very big; just enough output to be a base level of heating for extreme cold. Of course, if things catch on, then the truck stops will have methanol, or hydrogen, or natural gas or propane or any number of other sources to power a small heater.

By the way, the diesel motor and transmission is over 1 ton, I think. The heavy drive axles are probably another ton. The rest of the truck is pretty light... aluminum / fiberglass / plastic bodies, and two simple C channel frame rails. I'll bet Tesla has to change the frame rails to save any significant weight. I suspect a unitized body / frame with air suspension to hold the "fifth wheel". No matter what, without relatively light weight capacitors being used, the truck will be TONS overweight.

The aerodynamics is where Tesla already shines, so I have little doubt that any truck will be one of the lowest drag units out there. They need to get rid of those rear view mirrors!!!

The biggest mistake Tesla can make is to build the truck too "dainty". I have welded frame rails on "brand name" trucks that cracked under load. I suspect this is an area that saving weight will get a really bad reputation. Everybody expects the range to be less than a diesel, so that won't be a surprise, and they also expect it to improve over time (more range, quick refuel), so this won't be the shortcoming.

The Tesla truck needs to be as good or better than a Freightliner, Mack, Peterbuilt or Kenworth at a significant savings in fuel costs. Tesla will have to give it away to compete with the hydrogen truck guys (Nikola).
 
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#5
TonyWilliams said:
With a truck that has 1MWh of batteries (ten S-100D batteries... well over 5 tons of batteries) that is required to make the Class 8 truck go 333 miles, I suspect cabin heating is an afterthought. Heck, they could use a simple heater that burns diesel, that every truck stop will have. It can supplement battery heating, too. It doesn't need to be very big; just enough output to be a base level of heating for extreme cold. Of course, if things catch on, then the truck stops will have methanol, or hydrogen, or natural gas or propane or any number of other sources to power a small heater.

By the way, the diesel motor and transmission is over 1 ton, I think. The heavy drive axles are probably another ton. The rest of the truck is pretty light... aluminum / fiberglass / plastic bodies, and two simple C channel frame rails. I'll bet Tesla has to change the frame rails to save any significant weight. I suspect a unitized body / frame with air suspension to hold the "fifth wheel". No matter what, without relatively light weight capacitors being used, the truck will be TONS overweight.

The aerodynamics is where Tesla already shines, so I have little doubt that any truck will be one of the lowest drag units out there. They need to get rid of those rear view mirrors!!!

The biggest mistake Tesla can make is to build the truck too "dainty". I have welded frame rails on "brand name" trucks that cracked under load. I suspect this is an area that saving weight will get a really bad reputation. Everybody expects the range to be less than a diesel, so that won't be a surprise, and they also expect it to improve over time (more range, quick refuel), so this won't be the shortcoming.

The Tesla truck needs to be as good or better than a Freightliner, Mack, Peterbuilt or Kenworth at a significant savings in fuel costs. Tesla will have to give it away to compete with the hydrogen truck guys (Nikola).
Click to expand...

The low hanging fruit in the electric truck world is local delivery trucks and utility trucks. Over the road big rigs need to keep moving to make money and the supercapacitors efficient enough for EVs won't be available until at least the mid-2020s. However, any truck that spends at least half the day idle (like most delivery trucks) can charge while idle and there is an artificial market being created in Europe as a lot of city centers are banning ICE vehicles in the next decade. Delivery trucks will have to switch to electricity or use horse carts.

Outside of Europe there is a ready market for electric trucks too. The post office would love to replace their ICE fleet with electrics. The military is also looking at getting away from fossil fuels as much as possible. They have been seriously researching biofuels, but they would probably be interested in an electric truck chassis for some roles. For vehicles used in areas with good infrastructure like all domestic bases and most airfields, even in war zones, electricity will be abundant enough that it makes sense most of the vehicles on base be electric. Many bases have enough open land around them that can be filled with solar arrays and make the bases much more self sufficient. It would actually enhance security, the base would not be dependent on the grid for power to keep it's communications systems going as well as all it's other electric powered systems.

Nikola is aiming at the big rig market, but I suspect Tesla's first foray into the truck market will be smaller, local vehicles. Less prestigious, but much more practical with the tech we have available today and it's a huge market that is very ripe for the picking.
 
#8
Yes, like busses, local vans / trucks are a foregone conclusion. A local use van is not much different in concept than a car.

But, planning and design must be "to the moon", even if we only plan to orbit the earth.

Class 8 long haul trucking will take real work, and hydrogen CAN give it a real run, as well as increasingly better diesel motors.
 
#10
Certainly, today, it would be somewhat easy to make current 120kW Superchargers supply the car through left / right ports at up to 240kW DC.. No fancy "800 volt" stuff. The problem, as stated above, is neither the battery nor the vehicle cooling system can withstand that for more than a very short amount of time (if at all). By the way, the Porsche 800 volt car is only talking about 220 kW of charging. Folks like to jump to the theoretical limits of the charger (like 350kW and 400kW that is being casually used) as anything meaningful for the car. The Tesla Supercharger has a limit of 135 to 145 kW, but the Supercharger output and car input is only 120 kW DC max.

With the current charge module capable of 72 amps (72 * 277v = 20kW each), I suppose it would be possible to upgrade the current Supercharger box with 12 of these units for about 240 kW AC input, with about 200-215kW DC output capability (85-90% efficient).

The cooling issue could be routed off-board the vehicle, with a large heat exchanger sitting at every Supercharger. This would require a cooling fluid coupling to the car, much like the coupling used for battery swapping.

I think we all presume that the 2170 cell will charge faster, but I'm not as convinced. The larger the diameter of the cell, the harder it is to cool. In addition, we have no idea what chemistry is used, but it's safe to say that it won't be a radical departure from what they are using now... NCA. Tesla cannot afford to bet the farm on something radical, and they are way past experimenting with a Roadster.

As to super capacitors, they could be energized with other super capacitors to recharge vehicles. The Tesla Uber Charger could be chugging along at 1MW to charge up the Uber station capacitor, which would then get plugged into a Class 8 semi truck, which downloads to an onboard vehicle capacitor at 3MW. Obviously, there would be some time before the Uber capacitor could do this little trick again (about once per hour).

Using my example, a Class 8 truck with a 1MWh battery would charge in 20-30 minutes, and the load on the grid is 1MW. Currently, Superchargers already have a 500KVA transformer for 4 Superchargers / 8 stalls, so going to a single "pump" at 1MW isn't too crazy. Getting 5-10 Uber Chargers at one site would be an entirely different equation! Like the Gigafactory, it might take a lot of batteries nearby to be practical, particularly in rural areas.

This is the minimum that will be required for a Tesla truck to be competitive. At least 300 mile / 500 km range under load. 2-4kWh per mile) with 20-30 minute refill times every 150 miles (like Superchargers). The offset in increased donwtime over a traditional diesel truck can be offset with decreased energy costs, but the savings can be surprisingly small to non-existent:

$0.73 per mile @ 6.5mpg with $4.73/gal diesel (using $1.25 USD per liter in Europe equals $4.73 per US gallon)

$0.46 per mile @ 6.5mpg with $3.00/gal diesel (that will likely go up in price over time)

$0.38 per mile @ 8.0mpg with $3.00/gal diesel (latest Cummings X15 diesel motor at over 50% efficiency)

$0.57 per mile @ 0.35mile/kWh with $0.20/kWh electricity (California electricity can easily be over 20 cents, plus demand fees will inflate costs further)

$0.34 per mile @ 0.35mile/kWh with $0.12/kWh electricity (nationwide average US retail price, no demand fee)

$0.17 per mile @ 0.35mile/kWh with $0.06/kWh electricity (wholesale, Pacific Northwest retail, no demand fee)

My calculations for EV truck energy consumption are based one gallon of diesel #2 is 38kWh, so using 7mpg = 5.4kWh of diesel energy per mile. If we assume that is 45% efficient, and electricity is 85% efficient from the grid to the truck, plus truck consumption, then 2.86kWh of electricity is required per mile, or 0.35mile/kWh.

If electric trucks catch on, expect a road tax surcharge like diesel trucks pay on fuel per gallon, which will further narrow any savings with EV trucks.
 
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#12
This link is courtesy of Michael Russo at M3OC:
https://autconomy.com/2017/02/03/tesla-incs-first-autonomous-trucking-fleet-could-create-the-most-important-supply-line-in-america-by-2020/

Interesting article. A couple of points though... Tesla's need to 'double' the world's output of Lithium-ion batteries was based upon projections from late 2013. With the apparent success of the Model ☰ Unveil Part I in late March 2016, they have since increased the projected final output of their Gigafactory and revised their time schedule so that the original 'maximum' will be reached in/by 2018. The final Gigafactory will have three times its originally specified output by 2020, enough to supply 1,500,000 vehicles per year.

Further, Lithium is a rather abundant element, available just about everywhere, and amounts to no more than 'the salt in the salad' within the chemical formulation of Lithium-ion battery cells at barely 2% by weight/volume. It is certainly convenient to have Lithium available at mines so close to the Gigafactory, but is not of vast importance.

Also, I'm pretty sure that a Tesla designed autonomous semi truck will probably look a bit more like the MAN Concept Driverless Truck from a few years ago than a Freightliner.

MAN-driverless-truck.jpg


daimlers-autonomous-trucks-to-be-tested-in-nevada-1.jpg


teslasemi.jpg
 
#13
A megawatt battery pack with a 333 mile range might be a workable system for an essentially self driving truck. Musk has been hinting at much higher output D.C. Superchargers and the Semi version might plug in more than one snake charger for separate battery packs. It would be the Tesla "MegaTruck".

That's kind of the brute force solution. Every 300 miles or so the truck pulls into a Hyper Super charger station....snake robots connect and do the charge in 10-15 minutes.

A self driving truck that works 24/7 wouldn't be especially limited by stopping for an hour out of every 1200 miles to recharge.

It would have the same sort of advantages that Nikola promoted for their Hybrid Electric that it could handle Hills faster and more efficiently using superior power and torque on the upside and regen braking on the downside both saving brake wear and recapturing power.

It would probably cost twice as much as diesels up front but a fraction as much to operate considering both driver costs and lower energy and maintenance. Like other Tesla products it's stretching for a pure solution at an initial premium price. Like other Tesla products if it has an initial market it only gets stronger over time as battery costs fall and renewable electric sources get cheaper and more available.

Id picture something distinctive looking and sleek like the MAN concept but no custom trailer...it's got to pull any trailer. There would be some corporate image benefit to using zero emission pure electric trucks and they'd get noticed. This would be a breakthrough proof of concept product like Tesla Roadster rather than a mass market solution. It could still succeed at a pretty high price point.

Unlike Nikola's hydrogen fuel cell version which seems to be just a pretty rendering and unworkable fantasy technology, Tesla could likely build a MegaTruck and supporting charger network...the only real issues would be cost/price/capex not technology.
 
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#15
so, i was going to share my thoughts in the /r/teslamotors post, but it would have been lost in the crowd. as soon as i heard people talking about the long haul trucking biz, my mind did a 180 and though about the short haul trucks that go in and out of the port of long beach and los angeles everyday. meanwhile, there is a massive effort to reduce emissions of trains, boats and trucks at the port. the port of los angeles launched a program for clean trucks and was inundated with applications. meanwhile port traffic is likely to double in the next few years. im interested to see what tesla is going to be showing, but there sure is a market for trucks that dont cross the country every 5 days,
 
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#16
Here's a link to a rather speculative bit I wrote three years ago on the subject:


Companies like BYD seem rather content to do the short range fully electric haulers that are used at airports, train depots, and shipyards, typically out of the public eye. Those often have a range well below 100 miles, and often under 50 miles. Yes, it would be cool to have a fully electric bobtail/pup truck that could run from Long Beach to Victorville and back... But it would be even more suitable to be able to go from Long Beach to Las Vegas and back. Not all transport is nationwide, sure... But quick regional turnarounds can be handled on a daily trip fairly easily and are a big part of transport, just as are local delivery runs. No electric vehicle should be limited to a specific purpose. Better to be open to as many options of use as possible. Especially when it comes to trucks and heavy vehicles.
 
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#17
What if the batteries aren't in the cab but in the trailer itself?
Then Tesla builds trailer depots where drivers (or the trucks themselves) drive into the depot. He/she/it then deposit a trailer with depleted batteries and picks up a trailer with a full charge.
The truck then continues on to a new depot (maybe in a totally opposite direction) where it is repeated.
 
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#19
SageBrush said:
This is all extremely exciting, but I keep wondering about utility demand charges.
Click to expand...
If battery packs are swapped, demand charges are an absolute non issue, its just a matter of having a larger inventory of batteries at each station so they can keep charging them all day long and completely stop charging at peak demand hours.
If regular L3 charging is the way, those stations are going to have at least a few MWh worth of PowerPacks to create the same effect.
GF + 2170 cells is paradigm changing.
GF1 goal is 250GWh/yr in packs. 1% of a single year full production split over 1000 supercharger stations is a whopping 2.5MWh of storage per station. All it takes is demand charges over 10 years be higher than the cost of those powerpacks, I think its a slam dunk scenario. The busiest/largest super charger stations will eventually have 5-10MWh of storage each. Its the only way to make busy super charger stations become 100% solar powered, cause the trend is those stations won't have full net metering long term, it will be far more economical to produce and store most solar production than selling electrons for peanuts and then buying them at a premium later.
And lets not forget that stationary cells are either cheaper or more durable than chemistry for vehicles.

On the other hand, I bet Tesla will offer a wide range of pack capacity on those semis, perhaps even sub 200 mile range while hauling heavy loads. There's a lot of market for hauling heavy loads through short distance in urban environments where the zero emissions factor is an absolute requirement. Those are also the kinds of scenarios where regen is most significant (either urban stop and go or short hops between plant and nearby ports). For instance here in my state Fibria has a celulose plant ~3 miles from its own operated port (with heavy traffic between plant and port). There are similar scenarios for intra port transportation (imagine those ports that are 10+ miles long). In such scenarios, a smaller battery can make the EV semi outright cheaper than the competition, with the massive electricity savings an even bigger win, overwhelming any extra costs to having a few extra semis so L3 charging isn't required.
A cheap enough semi can haul a shorter trailer economically in places where perhaps a full length trailler is forbidden.

On the high end for semis that will travel long distance, I will decline to speculate and hope Tesla will amaze us.

There is a captive market of several municipalities that will mandate zero emissions semis once those are available in large numbers. Call it compliance semis. A very acceptable strategy as a first step towards a non compromise semi that can go for 6 hours at 60mph between charges/driver meals.
 
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