Hacker News Reader

Hacker News

Comment by schiffern | Hacker News Reader

Parent Full thread

schiffern

>just as newer battery chemistries moved away from cobalt

Tesla seems to be the leader here. Per Investor Day[0] and other sources, they

- developed low-cobalt and low-nickel cathodes, to reduce scarce battery metals

- increased overall vehicle efficiency to allow iron cathodes which are earth-abundant

- consolidated electronic modules to reduce microchips and wiring

- are soon switching to 48V, to further reduce low-voltage copper wiring (copper being a 'medium-rare' metal)

- switched from copper to aluminum high voltage conductors (per Munro Live), aluminum having better conductivity-to-weight

- reduced vehicle structure with structural battery design and 'gigacasting' manufacturing

Many of these seem to benefit from vertical integration.

Are any other manufacturers pushing as hard here?

[0] https://m.youtube.com/watch?v=Hl1zEzVUV7w&t=1875s

View on HN

> - are soon switching to 48V, to further reduce low-voltage copper wiring (copper being a 'medium-rare' metal)

The move of automakers to 48V has been in the works for a while:

* https://www.autoevolution.com/news/understanding-the-shift-t...

* https://whma.org/overview-of-48-volt-systems-in-the-automoti...

* https://www.google.com/search?q=48V+cars

It's just a bit of a co-ordination / chicken-egg problem in that equipment probably has to be to handle 12V and 48V for a while during a transition period.

> are soon switching to 48V, to further reduce low-voltage copper wiring (copper being a 'medium-rare' metal)

In an interview by Munro[1] , Elon Musk previously mentioned the desire to switch to 48V together with the desire to use PoE. Combining data and power over the same wires.

[1] https://m.youtube.com/watch?v=YAtLTLiqNwg

> Are any other manufacturers pushing as hard here?

Why would they. Most of those things are not sustainable.

You don't want alluminium wires in your car.

> You don't want alluminium wires in your car

Why not? I^2*r says that running 75% less current will generate 94% less heat.

Existing copper wires would be a disaster if cars ran on a 3V system. Aluminum at 48V will be fine, as long as it’s sized appropriately the same way copper is today.

> Why not? I^2*r says that running 75% less current will generate 94% less heat.

Thats not the argument, you can do that now with copper cables.

Aluminium is a good conductor, but it is reactive, brittle and not as malleable as copper.

also, copper has almost half the resistance per meter than aluminium. So even for solid bus bars, it doesn't make that much sense, unless you have structural bus bars.

Most car wiring harnesses are affixed to structural members and don’t need to flex.

And twice the resistance doesn’t matter. So you go one gauge bigger. If the material is cheaper, more available, and suitable, that’s fine. We don’t insist on gold wires because they’re “better” than copper.

It’s all tradeoffs. I don’t see a reason to be philosophically opposed to aluminum other than “it’s possible to do it wrong”, which is of course also true for copper.

> cheaper, more available, and suitable

Indeed, but automotive wiring is subject to intense and persistent vibration and heat cycles. so all those ties become stress points for fatigue to cluster around.

I'm not saying its never a good idea to use an aluminium wire loom, but I'm struggling to find a situation where its required

It's not really the flexible thing you picture with the word "loom."

The place Tesla used this was for fixed rigid bus bars, notably the "cable" from the charge port to the battery.[0]

Previously they used traditional stranded copper. Now it's a solid aluminum conductor, wrapped in insulation and protected by an outer aluminum tube.

These are thick high voltage conductors. I'm sure Tesla did their homework on flex and fatigue.

As for resistance, this is why I mentioned conductivity-to-weight as being the critical metric. Copper is over 3x as dense, at 9.0 g/cm³ vs 2.7 g/cm³ for aluminum. It doesn't hurt that aluminum is cheaper and more abundant.

[0] https://m.youtube.com/watch?v=hY9cxyvUu6I&t=1115s

> copper has almost half the resistance per meter than aluminium.

But 4 times the weight

The switch to 48v is for the low voltage which is normally 12v. The high voltage system is the 300v from the pack.

Aluminum is really easy to fatigue and fracture. In a car that is vibrating and jostling all the time, this could happen surprisingly quickly.

Airplanes flying for decades are made of aluminum.

Comparing car design and operating conditions to that of airplanes is kind of silly. The operating conditions of aircraft are far better defined and restricted.

Additionally, aircraft airframes are regularly inspected and fully radiographed at certain intervals. Components that develop flaws are changed out when the flaws are detected. The same is not true of cars.

Their cables?

Tesla isn't using aluminum "cables" either. They use the material for large rigid bus bars.

https://news.ycombinator.com/item?id=35014013

I would assume those "high voltage conductors" are more like rigid bus bars, and not flexible wires.

Edit: Judging by the picture on this article [1] I am wrong.

[1]: https://hackaday.com/2022/01/13/exploring-tesla-model-s-high...

Tesla does use traditional stranded copper too, but the aluminum I referenced is indeed a rigid bus bar.

https://news.ycombinator.com/item?id=35014013

It is really funny when West is discovering magic of cheap aluminum for wires, while former Eastern Block is ripping aluminum wires from walls because it is no.1 reason for fires.

Aluminum is perfectly fine as a conductor, and perfectly safe. In the USA, we've used aluminum for most of our power transmission and distribution since the beginning of "the grid". Everything from the power plant to the meter at your home is connected with aluminum.

Where aluminum causes fires is due to the fact that it expands and contracts more than copper does, and it can oxidize and corrode when not properly cared for (for example, when dissimilar metals are used, or when exposed aluminum wire ends are not properly coated).

We can assume that someone at Tesla is familiar with the properties of aluminum and can insure that they are using the right connectors to mitigate these issues. (or at least, we can hope)

The other problem in house wiring is that when you tighten down the screw to attach the aluminum wire to the terminal, the aluminum work hardens, and expansion/contraction/vibration will cause it to break.

Perhaps the decrease in reliability was pitched internally as a way to sell more Teslas in the future?

Unlikely: buying a replacement car because your previous one burst into flames usually involves staying away from the previous brand.

Yes, no class action suit destroying the company could ever come from that little conspiracy.

> It is really funny when West is discovering magic of cheap aluminum for wires, while former Eastern Block is ripping aluminum wires from walls because it is no.1 reason for fires.

Aluminum was used for a short time in the west for household wiring and was quickly outlawed.

It's commonly used for the main wire into homes. As long as it is sized properly and uses the appropriate connections it is fine.

Copper costs 6x Aluminium and is much rarer + in a car you want to be as lightweight as possible. You need a good reason to avoid it.

>You don't want alluminium wires in your car.

Why not?

I assume, for the same reason you don't want them in your house. It expands differently from copper as it warms, and the connections can loosen.

If Tesla has switched to aluminum I imagine they've found a way to fix that. Possibly by making the entire electrical system out of aluminum, so that it all expands the same way, or possibly a connector designed to avoid that.

The primary reason you don't want aluminum in your house is that homegamers will improperly do repairs, primarily replacing devices (receptacles, switches) with ones that are not rated CO/ALR rated. I doubt that failure will be as likely in the cars.

Properly terminated, there is no problem with aluminum wiring in your house. As another replier mentioned, most houses do have aluminum wiring in the run to the house and the run from the meter to the panel, and sometimes in the larger runs like stove and dryer.

It's also worth noting that the newer aluminum formulas like Southwire SIMpul, are not like the old aluminum like was installed in my house in the early '70s. But, buyers are still gunshy from the '70s, so copper is generally preferred

Have they delivered the robotaxis that were promised several years ago?

I don’t see why that’s relevant with the topic of reducing consumption of certain rare elements. Then failing at some of the goals shouldn’t detract from what has been accomplished. And if the end result is just electric cars that don’t use rara elements I think that’s a good thing, even without robotaxis

I assume that the relevance is that Tesla's claims don't count for much until they actually deliver. Elon Musk has a long history of misleading people about Tesla. Whether it's embellishment, overestimation of what they can accomplish, or outright lies is up for debate, but the fact remains that they habitually over-promise and under-deliver. I consider him and his companies to be completely untrustworthy. He could be selling water in the desert and I still would never buy another thing from him.

Do you mean habitually under-deliver with things like making the crazy claim that they will grow at 50% CAGR?

https://twitter.com/ICannot_Enough/status/161837414087616512...

> Elon Musk has a long history of misleading people about Tesla. Whether it's embellishment, overestimation of what they can accomplish, or outright lies is up for debate, but the fact remains that they habitually over-promise and under-deliver.

I think that everyone should look on his "forward looking statements" with a higher than normal degree of skepticism. He does seem to pull off a lot of outlandish stuff, though, so it doesn't pay to be too skeptical.

> I consider him and his companies to be completely untrustworthy. He could be selling water in the desert and I still would never buy another thing from him.

I don't think that that same level of skepticism is warranted towards his statements about what is true today. But then again, I haven't been following him very closely, so maybe his pant are constantly on fire.

Reading the original post, I assumed all of the things listed (except for one) are things that has been done already and not just promised by Elon. Buy maybe I’m wrong.

The majority of Teslas being sold right now use lithium iron phosphate batteries already. This isn't just some future plan, it's already largely implemented.

He's literally already delivered motors without rare earth elements (for other purposes) in production Teslas for nearly a decade now. He's already done what he's said he's going to do, he's just going to do it more.

This is about as silly as people who think he’s the messiah. He’s clearly over promised on many things, but he’s also delivered on a lot.

And spacex motto is turning the impossible into late, so he’s being pretty honest about his goals being off. What’s the issue? Why do you hate him so much?

Some people call that fraud

If missing a forecast was illegal then literally every executive in the world would be in jail. Elon isn't especially bad at forecasting, in fact he may be much better than average, but it's hyper focused on every time. Every time Larry Ellison at Oracle misses a forecast it doesn't become a talking point that's repeated literally a billion times every time someone mentions a computer.

Reply on news.ycombinator.com