The company brought in outside investigators, who found that Samsung’s manufacturers experienced different problems building and rolling out the Note 7 battery
Samsung announced that problems with battery design and manufacturing were the causes of the Note 7’s catastrophic failure, leading to the recall of nearly 4.3 million devices last fall due to spontaneous combustion, at a cost of at least $5 billion.
Koh said that Samsung set up a special test facility to replicate the conditions that led to the Note 7 fires. Samsung tested more than just the batteries, though, running tests on the Note 7’s software, fast charging technology, USB type C port, iris scanner, and waterproofing features.
None of these issues were found to be related to the combustion problem, however.
The investigators instead found, as many outside observers had predicted, that the problems lay in the lithium ion batteries, both the “Battery A” from the original devices and the “Battery B” that was rushed into replacement phones.
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A combination of design and manufacturing mistakes at companies A and B, which were respectively identified as Samsung SDI and ATL by The Wall Street Journal last week, meant that the original batteries and the replacement ones issued had their own unique fire risks.
Samsung and the investigators did not name “Company A” or “Company B,” though. (As of this writing, neither Samsung SDI nor ATL have yet issued statements.)
Sajeev Jesudas, President of UL’s Consumer Business Unit, described the problems found in the original batteries and the replacement ones. The original, Battery A, was deformed on the upper left and right hand corners when placed inside its casing, and the deformation was exacerbated by thin separators and the battery’s high energy density. The stress this put on Battery A meant that the separator could not keep the aluminum and copper foils from touching, which can cause an internal short circuit.
That is, because there wasn’t enough space around the corners, the battery folded up on itself and its internal safeguards wore away to the point of catastrophic failure.
In contrast, Battery B showed internal short circuits in different spots. And Battery B samples met Samsung’s current, temperate, and voltage safety standards. But, these batteries were found to often lack insulation tape and also have improperly welded joints. Battery B suffered less from design flaws than from manufacturing mistakes that were not caught in quality control before shipping out.
This was likely due to Battery B being hurried out as a replacement for Battery A by Samsung, to keep the Note 7 on the market. And ATL just couldn’t handle the demand, according to USA Today. That said, separator thinness and high power density also put stress on Battery B, given that it shared Battery A’s design, a design that originated not with SDI or ATL, but Samsung itself.
That size was an issue was further supported by Kevin White, Principal Scientist at Exponent. Their investigation showed that Battery B devices didn’t have spacing issues that deformed the corners of the battery, while Battery A samples were always folding up on themselves. Instead, Battery B samples caught fire because of the welding and tape defects on both the positive and negative electrodes inside the power plant, which caused swelling and overheating.
White also noted that many of the failures observed in the batteries are common with other kinds of lithium ion batteries, but tend to show up after a device has aged considerably and its parts started to break down, not early in its operational life as was the case here.
Holger Kunz, Executive Vice President for Products Business Division at TÜV Rheinland, then announced the results of an investigation into Samsung’s battery supply chain across South Korea, China, and Vietnam, which was the only real positive finding for Samsung and its partners. TÜV found that the logistics and assembly processes in all three countries met international safety standards, so did not contribute to the Note 7’s many woes.
Samsung made a significant concession to its own secretive corporate culture with the investigation, bringing in the three American and German firms to conduct the review. Samsung, unlike other smartphone manufacturers, has resisted outside review of its battery supply chain, but decided not to go down that path this time around due to the scale of the problem.
Koh closed out the conference by describing how Samsung wanted the Note 7 to be more compact yet have more power than similarly sized products so it could run more apps. He admitted that since Samsung had supplied the original designs to the battery makers, it was the ultimate source of the problems. Koh then promised that Samsung would expand its quality assurance practices, something the company did in 1995 as part of a sea change in its corporate culture then, to avoid further recalls. This includes maintaining an independent advisory group of academics, running “8-point battery safety checks” on the batteries, and changes to phone size and energy management software to reduce the risk of overheating.
Koh also said Samsung can now account for 96% of all Note 7s, leaving just 4% unaccounted for.