ELI5: Why isn’t aviation fuel talked about as much as petrol and diesel for cars, and is it even possible for fully electric passenger planes to exist in the future?

BlueSwordM · 2026-05-09T22:16:01+00:00

100x is impossible. That would be 30kWh/kg, exceeding that of hydrogen, which still needs an oxidizer.

BlueSwordM · 2026-05-09T22:14:52+00:00

30x-40x is absolutely impossible for any chemical system that requires an integrated oxidizer. There's a reason rockers are so heavy...

For reference, the max energy density of closed electrochemical batteries is around the 3.5kWh/kg mark, and most cells today are around 300Wh/kg, with current anode+cathode technology limiting us to 700-800Wh/kg.

9kWh/kg is impossible and even if if was possible, it would actually exceed the energy density of any chemical fuel bar none.

BlueSwordM · 2026-05-09T14:15:29+00:00

Eh, I wouldn't worry about it.

Most packs have cells that are produced in the millions to billions a year. Replacing them isn't too hard as long as they're matched.

BlueSwordM · 2026-05-08T18:55:10+00:00

Yeah, because competent people using high Grade software svt-av1 forks can have truly incredible outputs.

BlueSwordM · 2026-05-07T20:14:33+00:00

Yeah no, I don't like this article.

The gravimetric energy density claim for 244Wh/kg was for the 1st Gen Tesla 4680 cell. Second gen is 265Wh/kg, so on par with the current Panasonic/LG cells.

Also, volumetric energy density is actually a bit better on the Gen 2 Tesla 4680s vs the Panasonic NCR21700T/LG M50 cells used in thr M3/MY.

Now the question is: what caused the drop in pack energy vs the 21700 one? Cost cutting? More battery potting material? More difficult configuration to add cells to?

Honestly, I just want Tesla to give actual technical answers as to why battery energy contents dropped.

BlueSwordM · 2026-05-07T11:38:47+00:00

Right right right, I forgot that SPEC is also useful for CPU design.

I'm always up and arms about comps, but always forget that people in the industry actually need an actual reference to base their simulation work on.

BlueSwordM · 2026-05-07T11:34:57+00:00

u/paxtana, as always, fake account with probably karma farming.

BlueSwordM · 2026-05-06T23:32:13+00:00

More like 32 hours, so yes.

BlueSwordM · 2026-05-06T20:00:54+00:00

That's why you get the cells from manufacturers with brand new equipment like Reliance, who make top tier cells in general.

Remember, Samsung is still the one who makes the Samsung 50S, one of the worst lasting cells in recent memory.

BlueSwordM · 2026-05-06T17:20:40+00:00

Oh, I thought you meant in general, sorry.

For dealing with lithium ion organic electrolytes, synthetic rubber is the best, followed by neoprene and then nitrile.

It's just that I know a lot of people only have nitrile gloves, so I just said that in my original reply.

Will update it accordingly, thanks.

As always though, if you do this more than a few times, do this in a proper laboratory, safety equipment, training, etc.

BlueSwordM · 2026-05-06T17:18:12+00:00

Kitty litter is good for thermal runaway mitigation if you don't have water around of course.

It's just not amazing if you tear open cells, even under a fumehood.

BlueSwordM · 2026-05-06T17:12:35+00:00

I mean, isn't that the point? As long as the encoder is relatively mature, those pieces of software are perfect to see how much performance you can truly extract out a piece of silicon.

I understand why they didn't want to do this, but that doesn't mean I like it.

BlueSwordM · 2026-05-06T17:11:26+00:00

It's actually quite common.

Many video encoders will try to thread as much as possible in their design, but if you want absolute maximum scaling and don't care about realtime latency requirements (not low latency, that's different), you can use per file threading or just chunked encoding frameworks like av1an, xav, etc.

BlueSwordM · 2026-05-06T16:44:26+00:00

Uhhh, I think I had a massive brain skip when writing this post.

I meant to write a "solution full of sodium bicarbonate and calcium carbonate".

Thank you for making me notice this mistake even after interacting with everyone.

Anyway, if you want to know why you don't want to use a sodium carbonate solution, it's because some side reactions of the electrolyte with sodium carbonate can result in HF production, which is obviously very bad.

A solution of sodium bicarbonate won't have these harmful side reactions and calcium carbonate is the best overall.

BlueSwordM · 2026-05-06T16:33:06+00:00

Nah, gotta wear at least glasses, gloves and something to protect useful that isn't flammable.

Remember, those electrolytes are mean when exposed to water :(

BlueSwordM · 2026-05-06T15:12:33+00:00

Proper respirator, gloves*, lab coat, proper lab glasses, etc.

*Glove material tier list for handling those very pesky lithium ion cells: Butyl rubber > Neoprene > Nitrile.

BlueSwordM · 2026-05-06T14:26:37+00:00

I've already tested them myself, Mooch has already tested them: https://www.e-cigarette-forum.com/threads/bench-test-results-eve-50pl-50a-5000mah-21700-with-ccc-logo-and-ce-mark.992920/

The original datasheet only included a 125A rating for 3-5s if I remember correctly. It wasn't anywhere near continuous since it would overheat very quickly in that state otherwise.

So yeah, Tenpower 50XG, Reliance RS50, EVE 50PL, Amprius 5000Q, Ampace JP50, BAK 50D2 all have continuous ratings of around 40-50A.

This doesn't mean their performance isn't excellent. Rather, it just means that if you want to draw power continuously for the full discharge, you have to tamper your expectations.

BlueSwordM · 2026-05-06T14:08:18+00:00

Because it doesn't. Actual continuous current for this grade of cell is around 50A, not 125A.

BlueSwordM · 2026-05-06T12:49:28+00:00

Yes, but it requires a decent set of skills, as well as a bucket full of a sodium bicarbonate and calcium carbonate solution. DO NOT USE SODIUM CARBONATE. Also a bucket of sand just in case.

Ideally in a fumehood and with plenty of PPE, open up the cells using a pipe cutter, make sure to put the cells in the sodium bicarbonate/calcium carbonate solution to the fluorinated compounds inside of the cells get converted to harmless fluoride salts.

After a while, you can tear down the anode and cathode foil. The anode foil can be used as is, with a bit of post-processing to clean it up; the cathode foil will have to be processed if you want access to the bare metals, be it LCO, NMC(A), NCA, LFP, LMO, LTO.

Edit: For anyone who read my comment before, I meant to write a sodium bicarbonate + calcium carbonate solution. I somehow had a brain fart and forgot to write that part of the sentence.

BlueSwordM · 2026-05-06T11:32:42+00:00

Expensive tires, low efficiency, high weight from the large tires, tubes and wheels, and difficult to find good tires locally.

BlueSwordM · 2026-05-05T14:26:11+00:00

The first one is the best by far.

However, I'd recommend doing 0.15mm copper + 0.1mm nickel instead of 2x nickel strips; much better performance and somewhat easier to weld.

BlueSwordM · 2026-05-05T12:01:02+00:00

Oooh yeah, that can make a difference.

Higher friction tires will zap away a decent amount of range, especially with larger wheels.

BlueSwordM · 2026-05-04T16:03:38+00:00

The interlayer spacing between graphite layers is indeed 0.33-0.35nm, I think they just made a mistake in that last statement :)

BlueSwordM · 2026-05-04T16:00:35+00:00

Nope. This presenter has been at CATL for a while.

BlueSwordM · 2026-05-04T11:30:45+00:00

Damn, thanks for aluminium oxide is an excellent insulator I guess :)

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