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> 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

> 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.

eimrine 4y ago
> copper has almost half the resistance per meter than aluminium. But 4 times the weight
brookst 4y ago
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.
- KaiserPro 4y ago
  > 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
  - schiffern 4y ago
    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 https://m.youtube.com/watch?v=hY9cxyvUu6I&t=1115s
deleted 4y ago
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eimrine 4y ago

> copper has almost half the resistance per meter than aluminium. But 4 times the weight

brookst 4y ago

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.

KaiserPro 4y ago
> 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
- schiffern 4y ago
  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 https://m.youtube.com/watch?v=hY9cxyvUu6I&t=1115s

deleted 4y ago

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