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Comment by OxO4 | Hacker News Reader

The funny thing is that during the event, Elon claimed that the car can recharge the tanks itself [0], but in the Top Gear video, the Tesla folks say that it is recharged from an external source [1]. In the Top Gear video, they also say that they are filling it from a "high pressure nitrogen system", whereas Elon claims that the tank is filled with air. They can't even keep their own messaging straight.

[0] https://www.youtube.com/live/qt5p-_tE8d0?si=V5csPghK02wwd0or...

[1] https://youtu.be/JdkIOhFmbKI?si=ULvyIRWDRZRWlIWA&t=1340

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Elon _always_ lies and exaggerates during these things. He seemingly can't stop himself.

And the car would have 4 seats(now 2), over 1000 km range(now less than half), and be the fastest car period(now very far off). Then they say it will do 300 and something km/h, but also say it will do Mach 0.5. They are completely clueless, as usual.

I assume it's both...

it has its own pump, but if you don't want to wait 6 hours to recharge, you can fill it with a nitrogen cylinder.

The Top Gear video mentions that kind of recharge time using an external system (though they do claim that they are trying to get it down to 30min).

I've seen some claims that the gas is stored at a pressure of 10000 psi/690 bar in a 200 l tank. If that's true, then that is a gas volume of 138000 l. A commercial, stationary scuba compressor compresses around 850 l/min [0] to 350 bar. A compressor like that would take around 160 min just to compress 138000 l to 350 bar (so significantly less than 690 bar), is a _large_ appliance, and _loud_. Compressing gas quickly also produces heat. An on-board compressor seems quite unrealistic to me unless I'm missing something.

[0] https://www.bauer-kompressoren.de/en_en/pe-ve1

He's only 78% correct.

promise everything now, work out everything else later.

Perhaps they use liquid nitrogen and then just allow it to boil off inside the tanks? This would give them a safe and easy way to quickly recharge the tanks for testing.

Air is basically nitrogen. It can probably use both.

Based on a cursory search, propellant-grade nitrogen requires a high purity (99.99%) [0]. I am no aerospace engineer, but I'd be interested to know what the actual requirements are for a system like that to work reliably. If 99.99% nitrogen is actually required, then I'd assume that the corresponding compressor would neither be compact nor particularly maintenance-free.

[0] MIL-PRF-27401

Air often contains water though too which could cause problems with ice at the rquired discharge rates.

You’d want to dry the water beforehand, like is usually done in such things.

I think you meant air instead of water

It's pretty simple, actually, Elon is a pathological liar.

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