A Tesla semi might come with 500 kWh of battery and a number of DC charge points. It might go 500 km loaded. Being a truck, there is nothing to stop a driver carrying, say, a 100 kW generator on the trailer and wiring it in to the battery for on the move charging when needed. Vehicles designed to carry freight can be regarded as a hybrid due to their capacity to carry a portable generator. Electric semi-trailer manufacturers should wire their vehicles so an operator can plug-in a generator for on the more charging. Tesla should do it to.
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How hard would it be to make an electric semi truck
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Serial hybrids have lower efficiency than pure ICE vehicles while operating under constant load. Taht means you are better off with a diesel semi than with diesel-electric semi.
Garbage trucks and other stop-n-go trucks that spend their life in the cities are a different story.
Tesla should and probably will combine several of their technologies to disrupt the way long-range semis operate. Battery swapping, autopilot, supercharging, solar power, stationary storage, AWD with one motor per axle, ... exciting times are coming.
Garbage trucks and other stop-n-go trucks that spend their life in the cities are a different story.
Tesla should and probably will combine several of their technologies to disrupt the way long-range semis operate. Battery swapping, autopilot, supercharging, solar power, stationary storage, AWD with one motor per axle, ... exciting times are coming.
Red Sage
The Cybernetic Samurai
500 km is about 310.7 miles. If you presume there is perhaps a 5% buffer for anti-brick protection, the 500 kWh battery pack would have 475 kWh available for use. That works out to about 1,528.9 Wh per mile, and possibly as low as 1448.2 Wh per mile (with 450 kWh usable, a 10% buffer).
According to Popular Mechanics:
In 1973, the feds estimated that semis got about 5.6 miles per gallon of diesel; today's estimate is 6.5 mpg, although different trucks get fuel economy in a range from 4 to 8. Going up a steep hill, a truck's mileage might drop to about 2.9 mpg, while going down the same hill will raise it to more than 23 mpg.
A U.S. Gallon of diesel fuel holds 40.7 kWh of energy. So in a diesel semi truck, at 8 MPG, that is 38.8 gallons to cover 310.7 miles (500 km), or an expenditure of 1,580.6 kWh, and that works out to 5,087.5 Wh per mile. Of course, quite a bit of that energy is used up by creating heat, light, vibration, and sound... But if one presumes the diesel drivetrain is as much as 38% efficient (they aren't, that would put them about the same as a Prius), then the work of travelling the 310.7 mile distance is accomplished using only 1,933.25 Wh per mile, or a total of 600.6 kWh of energy. With that in mind, a battery powered drivetrain rated at only 85% efficient would need maybe a 742 kWh battery pack to ensure covering the range. That would be effectively the energy capacity of 18 gallons of diesel fuel, or around 22 gallons of gasoline. Personally, I'd hope Tesla would aim for a semi truck that was capable of 900 to 1,200 Wh per mile in the majority of situations. Even then, you might need 900 kWh of capacity to cover 600+ miles. So, perhaps they'll start with a nice 1,000 kWh or 1 MWh capacity.
Industrial level generators are best left in stationary applications. And if they are stationary, you'd might as well use a Supercharger or Battery Swap. Tesla Motors has no intention of giving any validity whatsoever to hybrid applications. Their position is that all hybrids are essentially a stop-gap 'solution' at best, and a delaying tactic at worst. If someone else wants to build the best possible hybrid semi truck, Tesla will simply aim to prove a fully electric semi truck would be BETTER.
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Just to point out to all the people gleefully predicting replacing freight rail with electric trucks, road damage goes up with the cube of the vehicle weight. So a truck does significantly more damage to a road than the passenger car does. Also, rails are just plain more efficient as long as the origin and destination are both on a track with a reasonable routing. That's why trains exist.
One calculation I haven't really seen here is what the annual fuel cost savings really would be for a diesel vs electric truck so you could evaluate what the ROI would be on an higher up front capital investment.
One calculation I haven't really seen here is what the annual fuel cost savings really would be for a diesel vs electric truck so you could evaluate what the ROI would be on an higher up front capital investment.
rw86347
Member
We shouldn't use semi's for shipping stuff we should have electric train tracks. No batteries necessary.
JRP3
Hyperactive Member
Here is a good starting place. David MacKay FRS: : Contents High school level math. Good overview, of the entirety of the energy picture. Remember that a lot of simplification was done, and you should be fine.
Thank you kindly.
Maybe not. Currently in the US, the spillage of methane is about 3 times the greenhouse gas equivalent of the CO2 saved over other fuels. So natural gas is making things worse.
Fleets of diesel-electric locomotives beg to differ.
Thank you kindly.
Not that I advocate natural gas as a long term solution, bus is the cradle to grave impact really 'worse'? Extraction, refinement, transportation, etc...
I don't have peer reviewed studies, but it would appear to be at least worth investigating. Natural Gas (Methane) is a potent greenhouse gas (25 times more than Carbon Dioxide). It doesn't take much spillage to make things worse. Of course, spillage isn't guaranteed, it could presumably be done better.
Thank you kindly.
Further, I seem to recall that natural gas pipeline companies are not required to report how many leaks they have. Could be just a few, could be a lot. So, some people at MIT did a study of leaks in the gas line system around Boston. They found on average 4 leaks per mile. That would translate into 1.3 million leaks along 300,000 miles of pipeline nationally. That's a lot of gas leaking.
Also, producing natural gas uses a gargantuan amount of water.
I was thinking about this the other day....
What if the trailers had the battery packs, the truck would connect and drive to the next drop point, where it would drop one box and plug it in, then grab another trailer that is already charged and so on. It would slow down the individual shipping time of the container, but driver time would not be delayed. The tractor would still have its own power pack as well for short distance.
What if the trailers had the battery packs, the truck would connect and drive to the next drop point, where it would drop one box and plug it in, then grab another trailer that is already charged and so on. It would slow down the individual shipping time of the container, but driver time would not be delayed. The tractor would still have its own power pack as well for short distance.
brucet999
Active Member
Interesting thought.
Tracking loads would be more difficult, as would be dispatching drivers.
What if you don't have another load following a charging cycle behind, thus stranding the cargo?
Those drop-off-and-charge locations would have to be secured somehow to prevent theft, of course.
And who would monitor SOC and disconnect when the trailer is recharged?
I would think that trucking companies could more easily manage battery pack swap stations at intervals along their routes, but that means increased labor cost.
It seem to me that Tesla could experiment with Electric Semi technology by building a fleet of electric trucks to deliver battery packs to Fremont from the GigaFactory. It's 261 miles, 4 hours on Interstates. The cool thing is that the trip down hill with all those heavy batteries could be powered by the cargo, and they could leave two or three of them in for the trip back, or just design the cab to hold three 100kWh packs that could be charged while loading/unloading the cargo.
Of course, it's probably more efficient to move them by train, since there are tracks right next door to the factory and only about a mile from the GigaFactory -- easy to lay a spur right up to the loading dock.
But it still would look cool to see an electric Semi driving down I-80 powered by its own cargo.
Of course, it's probably more efficient to move them by train, since there are tracks right next door to the factory and only about a mile from the GigaFactory -- easy to lay a spur right up to the loading dock.
But it still would look cool to see an electric Semi driving down I-80 powered by its own cargo.
brucet999
Active Member
This is exactly what I said a few pages back.
Another thing they could use the semis for is transporting incoming Japanese cells from the port of Oakland back to the gigafactory, for the next couple years anyways.
These would be purpose built truck trailer combos for battery packs, but the r&d gains from doing this seems like a potential for a huge payoff.
I've been thinking that it would be cool for Tesla to build an electric train to transport batteries from the Gigafactory to Fremont. Depending on how much battery capacity the motor would have, they might be able to do it entirely with renewable energy, charging it at the Gigafactory with its solar/wind sources. The fact that the uphill direction is with an empty load helps in this.
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