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Comment on A robot just swapped my electric car's battery

Nollij@sopuli.xyz ⁨11⁩ ⁨months⁩ ago

You lack imagination. What if they had multiple smaller batteries, as some cell phones do? The big reason it’s not more common in phones is that space is a massive premium, which is less of a concern in cars. Weight is a bigger factor here.

EV batteries have hundreds of cells that could potentially be charged in parallel. It’s even possible to do battery swaps one cell at a time, albeit that’s unlikely.

And these are just possibilities that I came up with as a non-EE. I’m sure they have their flaws, but it would bypass those physical limits.

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eerongal@ttrpg.network ⁨11⁩ ⁨months⁩ ago
This is already what they do. Dry batteries that are bigger than about your phone are generally comprised a whole lot of battery cells. If you ever take em apart, you’d basically see the cells are made up of what looks like a whole bunch of AA batteries (but larger).

They do charge “in parallel”, but that’s limited by how much electricity you can feed through into the system as a whole, and doesn’t speed up the process, it just makes them all fill at about the same rate.

Making the cells swappable is basically what this video is about.

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- Nollij@sopuli.xyz ⁨11⁩ ⁨months⁩ ago
  I mean separately. Why limit it to a single charging system? What if you had 2 (DC) charging ports, each capable of only charging half of the cells? Many heavy duty trucks have 2 gas tanks, each with a separate fuel door. They can be filled by 2 pumps simultaneously, cutting refueling time in half. What about 4? 10?
  
  Obviously there would be downsides (cost being a big one), but it would enable faster charging.
  
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  - eerongal@ttrpg.network ⁨11⁩ ⁨months⁩ ago
    I mean, this is still more or less what the fast charging standards do; they’re pouring more power into it faster with higher bandwidth cables and sectioned charging.
    
    The level 3 fast charger is basically the equivalent of 4 power cords from your wall. Also, adding more and more hardware and things for it will effectively make the electronics more complicated, which means more expensive, difficult to manufacture and repair
    
    But also, as you scale this up more and more you’ll start running into issues that make it difficult to start pulling more power; energy from the grid isn’t infinite
    
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phoenixz@lemmy.ca ⁨11⁩ ⁨months⁩ ago
Ugh, again…

Your imagination cannot break physics and just because you can imagine it that doesn’t mean it’s a good idea or that it would ever work on an engineering level.

Take Hyperloop. Anyone with a basic insight into engineering that takes more than two seconds to think about it can conclude that it’s a horribly stupid idea that will never come to reality, yet people have invested billions in it, universities jumped the Elon band wagon because… I don’t know why but for ducks sake, it’s stupid and will NEVER work. Meanwhile in that decade that the US was playing with the Hyperloop shit, china built out thousands of kilometers of high speed rail that actually works and the US is still stuck with the laughably sad Amtrak toy trains. What has Hyperloop done in a decade and tens of billions of dollars? NOTHING.

Just because Elon musk says it’s his idea (it wasn’t, but he lies all the time so there is that) doesn’t mean it’s a great idea.

Batteries as they currently are will NOT get any more efficient. “Yes but” No. Won’t happen “BUT” No. We might be able to squeeze a few % extra here and there but a doubling or anything like that won’t happen.

We might get a new energy storage solution where maybe we store electrons in a plasma cloud in a container or something (this idea is pulled out of my ass right here and now), THAT would be a revolutionary new energy storage that maybe could give us double, tripple storage capacity.

But to give you an idea of energy storage: even the best battery out here still doesn’t get beyond 10-20% of the energy density of gasoline. You want an electrical plane? Sure, make battery energy density about 5x better (that’s a 500% increase) than it currently is and we’ll talk. Until then, it’s physically possible but practically stupid as your batteries will use 50-70% if your aircraft. That is not mentioning what will happen in case of fire. Kerosine is flammable and a problem, but kill the airflow and it’s out. Batteries, on the other hand, are a bitch. A batteries catches fire and it will go until it’s done. A battery catching fire in an airplane is a problem. An airplane on batteries with one of those batteries catching fire is a “you’re fucked” situation. You won’t survive, you’ll get roasted. So again, engineering wise things aren’t that easy.

Take Elon’s SpaceX. Everyone wows it for doing stuff badly that NASA did great 50 years ago, I am not kidding. If NASA did as bad as SpaceX 50 years ago they would have been disbandoned, but SpaceX has deep pockets, apparently, and so people applaud fuckup after fuckup. It’s painful to watch.

I’m dumping on Elon now as he is the biggest abuser of “if I imagine I can then I can” bit he is far from the only one. Dreaming is fine but if you want to make it real then you HAVE to comply with science and engineering. You can solve complicated or hard problems with interesting solutions (flying an airplane with static wings, hello Orvilles)

Have an open mind, but not so open that your brain falls out, please.

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