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Comment by pcl | Hacker News Reader

> This presentation will demonstrate a feasible path for solid-state cells that possess a specific energy of greater than 400 Wh/kg to enable electric aircraft

Wow!! Gasoline is 12 kWh/kg. Only 4x better!

https://chemistry.beloit.edu/edetc/SlideShow/slides/energy/d...

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I am sorry but either math or English comprehension fails me. 12 000 Wh/kg vs 400 Wh/kg is 30 times better.

Regarding gasoline: the question is how much of that energy is actually converted into motion instead of heat. With electric mirrors it's more than 90%, with gasoline it's more like 30-40%.

I am sure you meant motours/motors, not mirrors.

Yes. Gboard is getting ever more useless.

And it never fails to capitalize brand names and suggest them over normal words...

If I talk about the malus genus it always tries to turn it into Apple. Just like that.

And what is with the numerical replacement of a word? Just before pressing send, if you're lucky, you catch something like, an engine may be defined by it's 6 in cubic inches. (Instead of displacement.)

I’m about to turn off autocorrect. It’s < handling of apostrophes makes me sound like an idiot, and it’s (that’s two) auto replacement of words makes me sound like I’ve had a stroke. A couple times I have checked a response I’m (three strikes) the morning and it is so garbled I can’t remember what I was trying to say.

It used to work better, right? I’m not imagining it?

Yes, I believe it did used to be better, I feel like I'm fighting the damn thing now.

10-13x better then

Basically if you figure a EB battery weighs 1000 lbs and 10 gallons of gas plus the tank weighs 75lbs.

Gets a lot better when you include the weight of a gasoline engine plus transmission vs an inverter and electric motor. The difference there is a few hundred lbs.

Take away is even what seems like small improvements in power density saves a lot of weight. Increase the density by 10% and you shave 90lbs off the battery and reduce the cars weight by 4%. Your gain is more than the reduction of the weight of the battery because cascading reductions in the weight of the cars structural elements.

The torque required for an electric vehicle to climb a slope quickly drains the battery (if the electric motor can climb it, and if the refrigeration can manage the temperature rise along the climbing time [hill, road, etc; constant torque]).

Combustion engines have a high torque, and these variables should be included in the equation. IMHO, it should be mandatory to include in the electric vehicle specification the range with a 14-20% of slope/gradient[1], including the speed.

[1] although it does exist some ways with 30% of slope, some wicked garages included.

Indeed. Clearly I shouldn’t do math in the morning! It seemed like an impossibly good number.

...isn't that 30x? Also, I saw it listed as 500Wh/kg from the article, where was the 400 figure coming from? At 500Wh/kg, it's about 24x the energy density.

Also the NASA paper was published a year ago, and the article linked in OP was published a few months ago. Is there some development that is causing this to surface again now?

I saw the 400 number in the abstract of the paper. And yes, terrible math on my part!

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