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csours

500-Mile Range! Wow! /sarcasm

How long is a piece of string? As long as you need it to be (as long as you keep adding more string)

Samsung Press Release: https://news.samsung.com/global/samsung-presents-groundbreak...

Concrete claims:

50% better volumetric efficiency for their prototype. No mention of pack or module volume.

> "the ultrathin Ag-C nanocomposite layer allowed the team to reduce anode thickness and increase energy density up to 900Wh/L."

1000 charge cycles.

No information about: temperature range, cell voltage, material cost, manufacturing requirements, impact sensitivity, a million other things needed for a commercial product.

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I will believe in Solid State batteries when iPhones come with them.

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Power to weight ratio is also interesting for a vehicle, not just power per volume. Some variant of the Rocket Equation must come into play because you need stored power to carry around your stored power.

"Rocket Equation", thank you! I've had a total brain-block on that term as I was literally just trying to answer a question related to this, on a Tesla forum, and I couldn't remember the name! The inevitable question of "Why can't they just add more battery for more range?" Like you mentioned it's some variant of this and I'm sure there is a name for it. I'm not a mechanical engineer. But again, dragging more mass requires more energy. In an automobile, you'd need a bigger and stronger car. My Model 3 is one heavy beast. More weight and it would need bigger (perhaps more) tires and a heavier/stronger drivetrain. The new Roadster was must have been planned for "some time in the future" production (not in production yet) because they have some formula that dictated a new battery was coming. A 620 mile range on a car that can do 0-60mph in 1.9 seconds (twice the range of my car) has to have some way of reducing that weight. Who knows. Fascinating problems. I wish I had gotten myself into that sort of engineering when I was young(er).

The Rocket Equation is important for rockets because they cannot pause and refuel like cars or even airplanes can. There's no compromise or trade-off in the rocket equation. For cars or airplanes you can have a smaller tank and more refuelling. Obviously for airplanes there is some minimal tank size where you can't actually take off, and some maximal tank size where your airplane doesn't have any usable cargo/passenger space.

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The limit for cars is almost always tires, as it is in this case. Or rather the interface between tires and the road. Weight always deforms the road surface, more weight deforms the road more, and at a certain point the road quickly breaks down.

Thus, governments put weight limits on vehicles [0]. In my state, it's 20,000 pounds for a single axle (it assumes you will be using a truck and loading the rear axle).

If we take that 20,000 pounds and subtract 2,000 for the cabin and the rest of the drivetrain, you could have 18,000 pounds of batteries. I think 18,000 pounds of batteries could take you a long long way.

As a cross reference, a Commercial Drivers License is only required at 26,000 pounds. https://en.wikipedia.org/wiki/Commercial_driver%27s_license

0: https://www.txdmv.gov/motor-carriers/oversize-overweight-per...

It sounds like the key promise of solid state batteries is shorter charge times (10x better according to [1]).

[1] https://www.popularmechanics.com/cars/hybrid-electric/news/a...

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