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Chinese EV maker BYD says new fast-charging system could be as quick as filling up a tank (www.theguardian.com)
submitted 2 years ago by to c/technology@lemmy.world
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[–] 21 points 2 years ago (15 children)

Maybe with a supercapacitor in the station and a chrging cable with the diameter of a fuel hose.

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  • [–] 16 points 2 years ago (4 children)

    Not really, just make the vehicle 800v and then use the same Amp limits. That's where everyone is out pacing tesla now. Tesla went for amps, the others went for volts

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  • [–] 10 points 2 years ago* (3 children)

    Energy is amp x volt. Same energy faster is more energy in same time, be it amps or volt. Dunno if your grid can bear it multiple times in each city but still better buffer it. And more volts needs more gum or you get the volts.

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  • [–] 1 point 2 years ago (2 children)

    P=i x v

    But also

    P=i^2 x r

    Power goes up with linearly with voltage but to thw square or I.

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  • [–] 2 points 2 years ago* (last edited 2 years ago) (1 child)

    That second formula is for how much power gets dissipated in a resistance (hence the R in it) , not how much power travels through a line.

    That said the previous poster was indeed incorrect - the required thickness of a cable through which a certain amount of power passes depends only on current, not voltage: make it too thin and it can literally melt with a high enough current and the formula of the power it is dissipating as heat that can cause it to melt is that second formula of yours and the R in that formula is inverselly proportional to the cross-cut area of the cable, which for a round cable is the good old area of a circle formula which depends on the square of the radius - in other words the thicker the cable the less current it can take without heating up too much or, putting it the other way around, the more current you want to safely pass through a cable the thicker it needs to be.

    In summary, thinner cables heat up more with higher currents (and if they heat up enough they melt) because even pure copper has some resistance and the thinner the cable the higher the resistance. If you need to move Power, not current specifically (such as to charge something), you can chose more current or to have a higher voltage (because P = V x I), and chosing a higher current means you need thicker cables (because as explained above the cables would overheat and even melt otherwise) but a higher voltage doesn't require a thicker cable.

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  • [–] 8 points 2 years ago (2 children)

    Assuming this is about the same thing as the other BYD charging article I saw a couple days ago, they're using a higher voltage, which would let them charge faster without needing a thicker* cable.

    (* The copper need not be thicker, but the insulation might need to be)

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  • [–] 3 points 2 years ago* (1 child)

    The copper need not be thicker, but the insulation might need to be

    Exactly. More energy means either more copper or more rubber in the cable.

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  • [–] 6 points 2 years ago*

    Rubber is cheap though, and flexible. If it's the size of a gas pump hose, oh well; gas pump hoses are also rubber. As long as they don't have to make the copper ridiculously thick, it shouldn't matter how thick the cable overall is

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  • [–] 4 points 2 years ago (6 children)

    I always imagined that portable future wizard (??nuclear??) power would be as simple as unscrewing a 5 gallon cannister from the back of a vehicle and exchanging it at the power/charging station for money. Like the small 20 lb LPG cooking gas tanks. I still think that electric cars are a phase of tech that cannot be sustainable in terms of money and environmental cost and waste for too long and that it is just transitional in our quest. Hydrogen power was always supposed to be the future in my mind.

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  • [–] 9 points 2 years ago

    Hydrogen has extreme structural problems. Hydrogen tanks need constant maintenance, due to how small the molecule is - it's very difficult to contain and prevent corrosion. You then have significant conversion loss between the powerplant-native format of electricity, and the hydrogen. So nothing can be as cheap as pure electricity. Fuelling the car with ammonia that then gets converted to Hydrogen inside the car is the solution to the first problem, but further increases the loss on the second.

    What you're describing sounds like a small, high-capacity battery to me! Like a super AA battery. Maybe in 50 years :)

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  • [–] 5 points 2 years ago (2 children)

    Hydrogen power is the past not the future it's just a past that never came to be so we sort of feel like it's something futuristic.

    It's a great idea in theory but there's so many problems with the idea not least of which is where do you get the hydrogen from? The amount of power that you would need to compress hydrogen into liquid on an industrial scale would practically necessitate dysonsphere.

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  • [–] 1 point 2 years ago (1 child)

    I think Toyota and Honda... maybe somebody else was developing a Hydrogen cell car. I remember seeing James May on Top Gear talking about it and driving it. It was in California. It seemed really promising and very exciting at the time that's why the memory imprinted on me a bit.

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  • [–] 3 points 2 years ago

    Toyota at least was getting their hydrogen from natural gas which rather defeats the whole point really.

    In order for hydrogen power to be sustainable it has to come from electrolyzing water. But the power requirements are prohibitive since the process is unimaginably inefficient. Something insane like 80% of the power goes to waste when converting water into hydrogen and then you've got to find a way of compressing that hydrogen and transporting that hydrogen.

    I'm not saying it's impossible but in a world where you can recharge an electric car in 5 minutes what's the point in even going to the effort of solving those problems.

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  • [–] 4 points 2 years ago

    Well, you'd need to standardise battery formats and legally mandate that they have to be easily switchable. I imagine that would get pushback from the car lobby - they do so love to make proprietary branded parts if you let them. If they can't force you to only use original parts for repairs because some part is generic by law, they'll lose out on precious markups.

    That said, the car lobby can go take a hike for all I care.

    The other issue is that it would have to be easily reachable, even if your trunk is loaded up. The underside is difficult to get at with any kind of setup you'd let amateurs touch. Maybe something on the side could work like you've already got for gas, depending on the weight of the battery. I'm sure it's a solvable problem, if there is some will to see it done.

    I'm all for the idea, mind you. This isn't me arguing against it, but rather trying to consider what's stopping us (and the answer is probably "rich people that don't like sharing" as usual).

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