Slashdot Mirror
Engineers Explain Why the Galaxy Note 7 Caught Fire (digitaltrends.com)
Engineers with manufacturing technology company Instrumental tore apart a Galaxy Note 7 to try and figure out what may have caused some devices to overheat and explode, causing Samsung to recall and eventually cancel all Galaxy Note 7 devices. In their damning new report, the engineers discovered the root of the problem appears to be that the battery is too tightly packed inside the body of the Note 7. Digital Trends reports: They discovered the battery was so tightly packed inside the Galaxy Note 7's body that any pressure from battery expansion, or stress on the body itself, may squeeze together layers inside the battery that are never supposed to touch -- with explosive results. Batteries swell up under normal use, and we place stress on a phone's body by putting it our pocket and sitting down, or if it's dropped. Tolerances for battery expansion are built into a smartphone during design, and Instrumental notes Samsung used "a super-aggressive manufacturing process to maximize capacity." In other words, the Galaxy Note 7 was designed to be as thin and sleek as possible, while containing the maximum battery capacity for long use, thereby better competing against rival devices such as the iPhone 7 Plus and improving on previous Note models. The report speculates that any pressure placed on the battery in its confined space may have squeezed together positive and negative layers inside the cell itself, which were thinner than usual in the Note 7's battery already, causing them to touch, heat up, and eventually in some cases, catch fire. Delving deeper into the design, the engineers say the space above a battery inside a device needs a "ceiling" that equates to approximately 10 percent of the overall thickness. The Galaxy Note 7 should have had a 0.5mm ceiling; it had none.
1. Design ultra-thin phone
2. Disregard warnings from engineers
3. Profits!
>"...what may have caused some devices to overheat and explode,..."
To my knowledge, NONE of them "exploded". Those that had actual problems had overheating which led to a fire. That is not an "explosion". That word was used by the media to stir up tons of inaccurate hype.
>"...causing them to touch, heat up, and eventually in some cases, catch fire."
Exactly.
What about stop making stuff super thin?
Hopefully this provides some motivation to stop equating thin with better.
Nah, who am I kidding, people are stupid.
As in most cases, going to extremes is rarely a good thing.
If they found the problem, it means that they can reproduce it. They were entirely unable to make their test unit fail due to the tight fit, nor were they able to observe that an increase in pressure of a phone in the off condition (under which at least one of the fires occurred in the v2 Note 7) *led to* a runaway thermal condition.
They're basically just speculating because they are looking for some clicks. This is about as conclusive proof as Trump has of 3 million illegals voting in California.
Is it just my observation, or are there way too many stupid people in the world?
If you're talking about things that happen with p < 10^-5 you can can't test to any kind of reasonable confidence level. Engineers have to use the collective experience of the profession as a whole as a guide, in addition to actual testing.
Since phone design is interdisciplinary -- involving marketing, industrial design and engineering -- engineers will just have to push back when the designers and marketers try to take that half millimeter away. This case will be a touchstone for future generations of EEs, the way the Tacoma Narrows Bridge is for civil engineers and Therac-25 is for software engineers.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
Having sat through management/engineer meetings it went like this:
Manager: Why are you wasting 10% there?
Engineer: We need design margin for tolerance stackup and thermal expansion.
Manager: But we'll lose sales! (in his head: "I'll lose my bonus!")
Engineer: We need design margin or there is a chance that some of the batteries could catch on fire.
Manager: So only a chance? Make the battery 10% bigger and stop complaining.
Engineers are measured and cautious in their statements. They talk in statistics, numbers, and probabilities, all of which have been lobotomized out of mid-level managers.
I don't understand the obsession with thinness.
Ever since my phone was less than 4cm thick I have been quite happy. What is this need to keeping shaving millimeters off?
If I had a DeLorean... I would probably only drive it from time to time.
Double glazed windows have a vacuum (or sometimes a noble gas) between the panes.
Or dry air. There's no need to use anything other than air to avoid condensation. You just need to make sure the air is dry and the windows are sealed so humid air can't get in. I doubt many windows are vacuum-filled; that's just begging for trouble, and would also limit the size of panes. 15 pounds per square inch adds up to a lot of pressure very quickly.
Note to ACs: I usually delete AC replies without reading them. If you want to talk to me, log in.
Phones have been sleek and stylish for years already.
Fashion isn't logical.
Irony: Agile development has too much intertia to be abandoned now.
Looks like I made a politically incorrect joke and got someone offended.
What has the world become...
...gis sdrawkcab (usually not responding to ACs; don't bother posting as AC)
It is, but not logical in that way. Fashion demonstrates that you can do something other people can't - whether it's spend more money, wear something that is inconvenient because you don't have to work, etc. What it's definitely not is about "getting something done efficiently". Quite the contrary, and hence the assumption of a lack of logic.
Phones have been sleek and stylish for years already.
But this one is really hot off the shelves. An absolute blast to use.