Nobuo said:
I think that like as other many cases, they do 24h torture tests, until they reach valuable results and extrapolate data. So they use that and previous real tests to make the data sheets. unless they have a time machine, is not really possible to predict precise behaviours
The paper shows you
cannot extrapolate calendar life based on aggressive cycle testing (torture tests), but you can infer it from charge slippage. Dahn's lab is the first lab that built chargers precise enough to do these type of measurements. That is why Telsa just partnered with them. Telsa has been hiring his graduates for over five years now to build chargers for their own battery lab. The goal of the gigafactory is not to build a cell with the highest energy/power density in the world, but to build a cell that will last 15-25 years in a car or grid battery. Tesla is playing a long term game. The Chevy Bolt may have higher density higher voltage (5V) LG Chem cells than the cells in the Model 3, but I can assure you they will degrade much faster. GM plays the idiot game, a.k.a. planned obsolescence
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LIVERMORE -- Imagine a world in which light bulbs never die.
People could live their whole lives without ever scorching their fingertips trying to change an incandescent bulb. Long after they were gone, the lights above their kitchen tables and bathroom mirrors would burn on.
That sci-fi vision might have become a reality if Adolphe Chaillet, inventor of Livermore's famous Centennial Light, and other early light bulb creators had continued on their way, according to the 2010 European documentary "The Light Bulb Conspiracy."
Livermore's bulb -- considered the world's longest burning as it nears 110 years -- is one of the stars of this illuminating film by director Cosima Dannoritzer, of Spain. On trial in "Conspiracy" is planned obsolescence -- the practice of deliberately designing products with limited life spans to drive consumerism.
"There's all these lovely conspiracy stories -- grannies always saying that everything used to last longer. I wanted to know (whether) that was just subjective or (if it) was really true," Dannoritzer said.
In fact, it was profit-driven scheming by industry titans, not technological limitations, that led to the evanescent incandescent bulbs of today, she contends.
In meticulous detail, the film lays out how, initially, manufacturers strove for long-lasting bulbs. Thomas Edison's first commercial bulb in 1881 lasted for 1,500 hours; soon, bulb-makers were proudly advertising 2,500-hour bulbs.
But in 1924, the main bulb manufacturers in America and Europe secretly formed a cartel to limit the average life of lamps to 1,000 hours, according to internal documents, Dannoritzer said. By the 1940s, 1,000-hour bulbs became the standard.
Eventually, the cartel was exposed, and in 1953, General Electric and other industry leaders were banned from limiting the light bulb's life span.
Although many patents have been awarded since, no super-long-lasting incandescent bulbs have succeeded commercially, the film argues.
Donated to Livermore's fire department in 1901, the Centennial Light was made by the defunct Shelby Electric Company in Shelby, Ohio, in the late 1800s. Documents suggest its inventor, Adolphe Chaillet, hoped to create a more efficient, long-lasting bulb.
"It struck me as almost ridiculous that this 100-year-old technology is still functioning. I thought for sure that all the physics must have been worked out," said Debora Katz, a U.S. Naval Academy physics professor who first learned about the bulb when it was featured on the "Mythbusters" television show.
Intrigued, she sent her students to dig up Chaillet's patent. Its contents were disappointing: Only the configuration of the filament and the shape of the handblown glass he used in an effort to reduce light refraction and better direct the bulb's light were described. Information that might have shed light on his bulb's life span, such as the composition of its filament and the gas surrounding it, were absent.
Livermore's bulb can't be tested directly for fear of destroying it, Katz said. Still, experiments conducted on identical Chaillet bulbs might hold clues.
To determine its thickness, Katz's team shined a laser on a Shelby filament and measured the pattern produced on a screen behind the bulb. The results showed Chaillet's filament was eight times thicker than that of a modern bulb.
Another difference is wattage. Modern household bulbs range from 40 to 200 watts -- the Centennial bulb now gives off 4 watts, about as strong as a night light. Thought to have been a 30-watt bulb when installed, the Livermore light seems to have decreased in power over time.
"You can think of it as sort of an animal with a low metabolism. It's giving us less energy per time, so it can keep on going longer," Katz said.
Other data add credence to the reports that the Centennial Light filament was carbon-based -- the norm before tungsten filaments were introduced in the early 1900s. The results are documented in "The Centennial Light Filament," a 2010 paper by one of Katz's former students.
Author Justin Felgar found the hotter the Shelby got, the more electricity got through it. The opposite is true for modern tungsten filaments, suggesting the Shelby filament is made of something else.
To determine its makeup, Katz said she wants to rip apart a Shelby bulb that isn't functioning and run its filament through the Naval Academy's particle accelerator -- hopefully before the Centennial Light's 110th birthday in June.
"Perhaps there's just some fluke with that particular (bulb)," Katz said, adding, "I think we should at least be able to talk about what the differences are between the Shelby bulb and the contemporary bulb. Whether those differences account for longevity, I don't know."
