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The Tesla Semi Is an Engineering Failure

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Re: The Tesla Semi Is an Engineering Failure

#31

Post by mcguire »

jimkleiber wrote: post #9
RobinL wrote: post #6

The video argues that, with current battery technology, to achieve the same range as a current semi, most of the weight of the truck will be batteries, leaving little weight for cargo (3 tonnes relative to 19 tonnes). I've noticed there is a common theme to arguments against electrification: that they assume it's necessary for an electric vehicle needs to match all the capabilities of a fossil fuel equivalent. i.e. t…

Or just swap out the batteries on the way. I think someone on here once suggested to do so at existing weigh stations in the US.

Does the Tesla semi have hot-swappable battery packs?

Re: The Tesla Semi Is an Engineering Failure

#32

Post by mcguire »

RobinL wrote: post #6

The video argues that, with current battery technology, to achieve the same range as a current semi, most of the weight of the truck will be batteries, leaving little weight for cargo (3 tonnes relative to 19 tonnes). I've noticed there is a common theme to arguments against electrification: that they assume it's necessary for an electric vehicle needs to match all the capabilities of a fossil fuel equivalent. i.e. t…

In this case, not matching the range of existing trucks means that you need to have more trucks and more drivers.

Re: The Tesla Semi Is an Engineering Failure

#33

Post by mcguire »

nehalem wrote: post #28
fallingknife wrote: post #19

This video is bullshit. The 1:20 ratio for battery weight is nonsense. A Model 3 long range has a 1060 lb battery vs 20 gallons of gas which weighs 126 lbs. So it's more like 8.5x. Also he doesn't take into account the simplicity of an electric motor vs a ICE engine. e.g. an electric truck doesn't need a transmission, so there will be a lot of weight savings there.

It is also noteworthy that the video assumes that the truck would carry a battery equivalent of 1135 litres of diesel. But driving about 600 km a day at 30l/100km the truck only needs about 180 litres (140 kg) of diesel a day. Even with the 1:20 ratio, that would result in a 2.8 tonnes battery. Still punishing in terms of load capacity but much more realistic to offset through weight savings along the drive train.

The typical diesel semi drives 950-1050km per day [in the US].

Re: The Tesla Semi Is an Engineering Failure

#34

Post by mcguire »

MrBuddyCasino wrote: post #5

I realize this won’t make a huge difference, but how much does the Diesel engine, transmission & drivetrain on a conventional truck weigh?

The video assumes the Tesla semi weighs the same as a traditional diesel semi. Tesla doesn't seem to publish the weight of their Semi, which is awkward.

Most of the weight is likely going into the frame and structure of the tractor.

Re: The Tesla Semi Is an Engineering Failure

#35

Post by chakhs »

mcguire wrote: post #30

Interesting. The problem described is the load capacity. According to the video: The maximum capacity of a truck is 80,000 lbs or 36 metric tons. The average weight of a semi-tractor is 25,000 lbs or 11t, leaving 25t for fuel, trailer, and cargo. 300 gal of diesel at 7lbs/gal is 2100lbs or about 1t. A trailer is around 10t. That gives a cargo capacity of 14t. The difference between the Tesla and a typical semi is tha…

The trailer was included in the semi weight in the video.

No idea why it was flagged I thought it was interesting.

I hope Tesla will release their numbers sometime soon.

Re: The Tesla Semi Is an Engineering Failure

#36

Post by mcguire »

RobinL wrote: post #21
rgbrenner wrote: post #15

When I see insiders in the industry adopting new technology, while a commenter with no background in the tech says it's terrible.. I'll generally believe the industry experts. Tesla has presold hundreds of these trucks to walmart, fedex, etc. The question is what did he miss... Here's the first big mistake I think he made in the video at 3:45. He pulls this "1 to 20" number out of no where to come up with a battery w…

Thanks, I was curious about that. Key quote for others: > [...] Tesla would need a 600 kWh to 1,000 kWh battery pack to produce the Semi’s 300-mile (483-km) and 500-mile (805-km) variants. Since a 600 kWh pack weighs about 8,000 pounds (3,629 kg), it would eat into payload as Class 8 trucks have a total weight capacity limit of 80,000 pounds (36,287 kg). That would mean 6050kg for the 500 mile range. The video estima…

Technically, the video assumes the Tesla would have the same range as a diesel tractor.

Re: The Tesla Semi Is an Engineering Failure

#37

Post by aurizon »

I feel this is a work in progress = the delays. The drive train will be lighter, and the new battery cells will also be lighter, but it seems to me that a well designed frame will also be needed to maintain the usual 36 tonnes load and keep within the total max weight. It is possible that a rules variance for electric trucks will be requested - and granted to raise the total by 4-6 tonnes with the same 36 Tonne load, since this will help meet the carbon lowering that mankind MUST have. IC engine makers will fight this, but not strongly as they see the need for electric and will also back Tesla. Tesla has stated he will mutually allow access to all Tesla patents, so a convergence towards an EV truck will emerge. Those who refuse access to their patents will soon fall behind the Tesla de-facto patent pool. This is much like the way the radio patent pool worked.https://www.jstor.org/stable/792163. Back in the days of Kitty Hawk the right brothers were classic patent trolls and never made another major advance - and set back US aviation for many years.https://time.com/4143574/wright-brothers-patent-trolling/

Musk is well aware of this and has been very creative in earning many new and valuable EV patents. I expect these to serve him well in creating this pool.

Right now his cars are battery starved and he is unable to fill all his own needs, and others are also after lithium and related minerals - I expect lithium reserves will serve adequate, esp if other metal battery techs emerge - it is quite possible lithium will be surpassed by a new-tech battery?

Re: The Tesla Semi Is an Engineering Failure

#38

Post by rascul »

chakhs wrote: post #17
RobinL wrote: post #6

The video argues that, with current battery technology, to achieve the same range as a current semi, most of the weight of the truck will be batteries, leaving little weight for cargo (3 tonnes relative to 19 tonnes). I've noticed there is a common theme to arguments against electrification: that they assume it's necessary for an electric vehicle needs to match all the capabilities of a fossil fuel equivalent. i.e. t…

Cargo transport needs long distance and big capacity. You don't need those in cars so they're not comparable. The video is not against electrification, it just argues it doesn't work with cargo transport, it is very inefficient.

> Cargo transport needs long distance and big capacity.

In the US, "Approximately 50 percent of the weight and 37 percent of the value of goods were moved less than 100 miles between origin and destination in 2015" according to the Bureau of Transportation Statistics [0]. This is well within the range of the Tesla Semi. I'm not sure the capacity of the Tesla Semi, though.

[0] https://www.bts.dot.gov/sites/bts.dot.gov/files/docs/FFF_201...

Re: The Tesla Semi Is an Engineering Failure

#39

Post by mcguire »

chakhs wrote: post #35
mcguire wrote: post #30

Interesting. The problem described is the load capacity. According to the video: The maximum capacity of a truck is 80,000 lbs or 36 metric tons. The average weight of a semi-tractor is 25,000 lbs or 11t, leaving 25t for fuel, trailer, and cargo. 300 gal of diesel at 7lbs/gal is 2100lbs or about 1t. A trailer is around 10t. That gives a cargo capacity of 14t. The difference between the Tesla and a typical semi is tha…

The trailer was included in the semi weight in the video. No idea why it was flagged I thought it was interesting. I hope Tesla will release their numbers sometime soon.

Ooh, good point. Should have read my own backup sources! :-)

"A semi-truck without a trailer weighs between 10,000 and 25,000 pounds, depending on the size." (https://www.tcsfuel.com/blog/truck-weight-classification/)

That's 10-11t.

Re: The Tesla Semi Is an Engineering Failure

#40

Post by aurizon »

mcguire wrote: post #31
jimkleiber wrote: post #9

Earlier quoted context omitted.

Or just swap out the batteries on the way. I think someone on here once suggested to do so at existing weigh stations in the US.

Does the Tesla semi have hot-swappable battery packs?

Not as far as I know, but a standard may emerge, as there is not way that an interstate system can operate if they all had hot swaps for each maker of trucks. I am sure they makers will develop a standard if swapping wins this game.
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