The Tesla Semi Is an Engineering Failure | Hacker News Reader

The Tesla Semi Is an Engineering Failure

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34 pointschakhs43 comments

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. trade offs are not possible.

Why can't the truck just have shorter range (and thus more cargo capacity) and charge more regularly?

If there was proper carbon taxing, the cost of the driver waiting around for charging would be mitigated by the savings made from avoiding carbon tax.

Similarly with electric cars, I'm happy to stop on a very long trip for charging if it means my environmental impact is significantly lower.

I'm assuming the maths in the video is correct. The key figure seems to be that you need 20kg of batteries to achieve the range of 1kg of petrol. Which sounds plausible, but I'm no expert.

The history of the entire industries that have a perfectly functional (more functional) alternative re-factoring themselves to match some new offering is quite poor.

I agree that industries will not do this voluntarily. They will just chase a profit. Climate change is a market failure so we need governments to change incentives to make it in industries' interest to change. A carbon tax is one option.

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.

Swappable battery packs seem like a good idea. It might even be faster than waiting to pump 100 gallons of fuel.

I'm thinking existing truck stops would have a better chance of working than the weigh stations. let's leave the government it, they are barely competent at weighing a truck. Some trucks might not see a weigh station for a week. Some stations are nothing more than a pull out on the side of the road.

Ah good point, I like that idea, especially as it utilizes that infrastructure and doesn't make them disappear when there's a transition to electric.

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.

>Why can't the truck just have shorter range (and thus more cargo capacity) and charge more regularly?

This seems inevitable in the short term. But then, the trade-offs tilt less in favour of electrification. For example, shorter ranges likely means more trucks, and these trucks will likely be heavier and do more damage to roads.

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...

It can be used to transport battery while using it?

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

who pays the driver during the recharging? The truck absolutely need to match the driver endurance, so that recharges can be planned during drivers downtime. The trucks are expensive, sure, but an asset. Drivers are the cost.

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 weight of 17t. But we know a 600kwh battery is 8000lbs.[0]

This article also mentions that the max legal payload is increased by 2000lbs for ev trucks... meaning the payload is going to be very close to a gas truck.

0. https://insideevs.com/news/525765/tesla-semi-payload-compara...

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 estimates it at 17t

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

> But we know a 600kwh battery is 8000lbs.

From your own source it says 600kwh will only go 300 miles. Trucks are too big to use the existing supercharger network so a new one will have to be built for the truck to get any substantial distance.

> I'll generally go with the industry experts. Tesla has presold hundreds of these trucks to walmart, fedex, etc.

Do you have details on the terms of these deals? Dollars to donuts these companies can opt out without penalty. This is just a mutual marketing scheme between Tesla trying to seem like an industry leader and these companies trying to seem green.

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 that the 1t of diesel is replaced by batteries, (according to the video) at a rate of 1lb to 20lb. As a result, the Tesla load capacity is small (or negative, according to my calcs here).

This is wrong.

I think the 1t of fuel is calculated as part of the 25t of semi tractor, rather than a separate weight. But that's a minor problem.

The big difference is that the range of a semi on 300g of diesel is about 1200 miles. The claimed range of the Tesla is a maximum of 500m. Therefore, the Tesla battery is comparable to 125g of diesel, or 875lbs, or about 1t. As a result, the Tesla should have about the same load capacity as a normal semi, just with 42% of the range.

On the other hand, that range is a problem. Truckers routinely complain about speed limits and limiters, because the difference between 55mph, say, and 70mph over a 10 hour (say) driving day is 150 miles. Drivers get paid by the mile, so that is some number of hundreds of dollars per day.

The Tesla's range of 500 miles per day (how long does it take to charge, compared to the driving hours schedule?) compared to the 600-700 miles per day of a typical semi is again some number of hundreds of dollars per day.

Does the Tesla have a hot-swappable battery pack? And how much does the Tesla tractor weigh? And why is this article flagged?

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.

I understand the drivetrain weight argument, but this guy makes money off these negative viewpoints so.. now my YouTube feed is gonna be conspiracy theories.

I hope YouTube does not correlate criticism with conspiracy theories

> conspiracy theories

I get the feeling you use this phrase to dismiss anything you don't like. Nothing about this video at all describes or relates to a conspiracy.

Nope, try it. Open and private browser and only watch that video.

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?

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].

The video does make a good point about the load capacity being at best half of what current trucks have. I wonder what the range would be at 45MPH vs 60MPH.

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

I just copied "Diesel engine, transmission & drivetrain" and "weight" into Google and this is what the search revealed. Maybe this could be helpful?

https://dieselsales.com/diesel-engine-and-transmission-weigh...

Wikipedia has you covered: https://en.wikipedia.org/wiki/Power-to-weight_ratio

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.

It all depends if a fully loaded truck is going up or down the hill, regen of electric semi will be crazy good

it might make more sense to use this to transport batteries while using them? Since the batteries are rechargeable - that would help the truck run and also transport the battery. Win-win.

That'll make the vehicle single purpose though

> “Did Elon Musk do it? Did he finally create something that isn’t a worse version of what we already have?”

This statement strikes me as ignorant even if we talk exclusively about Tesla. The idea that Elon hasn’t improved on existing designs across all of his current companies (or Paypal) borders on indefensible. Reusable and landable stage 1 boosters come to mind.

The YouTuber made similar videos about Hyperloop and city to city rocket travel so that joke was referencing those

Why do people always bring up accomplishments at spacex in arguments about Tesla

>Why do people always bring up accomplishments at spacex in arguments about Tesla

I think some of these people believe Elon is personally designing and engineering these things, so naturally it carries over.

Gwynne Shotwell doesn't get enough credit.

Good point about shotwell. I just dont like if someone criticizes like the tesla freight truck cargo capacity. someone brings up that engineers at spacex figured out how to land rockets

>(or Paypal)

It's odd people bring up PayPal as a star on Elon's resume.

    a) PayPal, especially in the early days, was near universally reviled.  It was sort of what we were stuck with.

    b)  Elon became part of PayPal in a merger, and was later removed as CEO.

I've seen people say Musk "revolutionized online payments". That's pretty revisionist.

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