After testing 200,000 Note 7 smartphone including the testing of fast chargers, Iris scanners, wireless charging and water proofing, Samsung has come to the conclusion that it was a short in a secondary battery B that was the primary problem that caused a global recall of over 3M smartphones.
Samsung’s mobile chief, DJ Koh, and other executives said that as a result of their investigation Samsung plans to improve quality control across their entire mobile production network.
Samsung says two different battery flaws were to blame for the fires that plagued its flagship Galaxy Note7 smartphone leading to two separate recalls and, ultimately, the permanent withdrawal of the model from the market.
According to Samsung, the new investigation shows that problems were isolated to the batteries, and were unrelated to other hardware components or the software that manages energy use in the device. However, some experts say that Samsung’s drive to make thinner phones with longer battery life may have contributed to the problem.
In addition to its own investigation, Samsung contracted with independent groups, including Underwriters Laboratories, to look into the causes of the fires.
The company used batteries from two suppliers in its Note7 phones—a company division called Samsung SDI and a separate company, Amperex Technology Ltd., that makes batteries for many smartphone brands. Samsung officials said the batteries from the two companies were designed and manufactured differently, and failed for separate reasons.
That distinction is important, because it helps explain the unusual sequence of events during the recalls late last year in Australia.
Samsung first said it was stopping sales of the phone on Sept. 2, and announced a formal recall on Sept. 15.
Samsung’s mobile chief, DJ Koh, and other executives said that as a result of their investigation Samsung plans to improve quality control across their entire mobile production network.
Samsung says two different battery flaws were to blame for the fires that plagued its flagship Galaxy Note7 smartphone leading to two separate recalls and, ultimately, the permanent withdrawal of the model from the market.
According to Samsung, the new investigation shows that problems were isolated to the batteries, and were unrelated to other hardware components or the software that manages energy use in the device. However, some experts say that Samsung’s drive to make thinner phones with longer battery life may have contributed to the problem.
In addition to its own investigation, Samsung contracted with independent groups, including Underwriters Laboratories, to look into the causes of the fires.
Data from Wall Street Journal.
The company used batteries from two suppliers in its Note7 phones—a company division called Samsung SDI and a separate company, Amperex Technology Ltd., that makes batteries for many smartphone brands. Samsung officials said the batteries from the two companies were designed and manufactured differently, and failed for separate reasons.
That distinction is important, because it helps explain the unusual sequence of events during the recalls in the fall. Samsung first said it was stopping sales of the phone on Sept. 2, and announced a formal recall on Sept. 15 in cooperation with the Consumer Product Safety Commission. But, with permission from the CPSC, Samsung began distributing replacement Note7 phones just a few days later.
Now, Samsung is saying that its investigation shows there was no reason to believe the new phones would malfunction. “It was a very tough period, and we are sorry,” DJ Koh, Samsung’s global president of mobile communications, said during the briefing. “The most important thing for us is customer safety,” and, ultimately, “earning back customers’ trust.”
Li-ion battery structure
Samsung says that fires in its Galaxy Note7 phones were caused by battery defects that led to short circuits. (Illustration supplied by Samsung.)
How Defects Led to Short Circuits
Like other Li-ion phone batteries, the Note7 batteries were made of sheets of material that served as positive and negative electrodes, with a separator between them. The electrodes and separator were folded up into a “jelly roll,” and then inserted into a pouch or casing.
Chemical reactions in a battery’s electrodes allow an electrical charge to flow between them, generating a current that flows through a circuit and powers the device. Normally, the electrodes don’t touch; if they do, a “short circuit” is created, and that can spark a fire.
During the presentation, executives showed a CT scan of a Note7 from before the first recall, in which one corner of the battery’s pouch impinged on the jelly roll, deforming the negative electrode. In some consumers’ phones, the positive and negative electrodes touched, causing a short circuit.
Samsung officials said that the company found that flaw before Sept. 15, and could see that wasn’t present in batteries made by the second supplier. At the time, the company did not disclose those details to the public.
We “were very comfortable” switching all battery production to the second manufacturer, marketing senior VP Justin Denison said.
Fires in the second group of batteries were caused by a manufacturing defect, Denison said. A sharp edge, or burr, was created by inconsistent welds in one section of the battery, the “positive tab.” (See illustration, above.) In some cases the burr pierced insulating material and the separator between the two electrodes, causing a short circuit.
Thin Design a Contributing Factor
Samsung says its investigation involved 200,000 handsets, 30,000 standalone batteries, and 700 engineers working in a dedicated facility. Phones were tested with the back cases both on and off (see photo at the top of the article) and with various types of software running. They were evaluated during both rapid and standard charging. According to the company, batteries tested on their own failed at about the same rate as complete phones did.
This may show that no hardware beyond the batteries was at fault, but others in the battery industry say that smartphone design trends are making flaws more likely.
According to Samsung, the Underwriters Laboratories investigation concluded that thin separators could have contributed to the risk of short circuits in both Note7 batteries. UL would not comment for this article.
If you want safer batteries, according to Hu, you’ll probably be looking at a bulkier phone with a removable battery. “They have a protective plastic case and may even have a gas relief valve to diffuse volatile conditions,” he says. “Non-removable batteries don’t have a case—just aluminum foil wrapping.”
The other option for phone makers, according to Hu, is to create a very thin phone with a shorter battery life.
Successful Recall
The saga of the Galaxy Note7 is ending with a singular accomplishment: one of the most successful recalls in history, as measured by the number of products that were recovered from consumers. As of mid-January, Samsung says 95 percent of all Galaxy Note7 smartphones have been returned in Australia Vs 97% in the USA.
“A 95 percent recall rate is almost unheard of,” says Pamela Gilbert, a former executive director of the CPSC who is now a partner at Cuneo Gilbert & LaDuca, LLP. The historic figure is often less than 50 percent, she says, even when auto safety is concerned. “People have an amazing ability to avoid doing things in their best interest if it’s inconvenient.”
Like Consumer Reports and some other organizations, Gilbert was critical of Samsung in September for not involving the CPSC quickly enough. During the Consumer Reports briefing, executives said that the company notified the agency of problems on Sept. 2. (Officials at the Consumer Product Safety Commission declined to comment for this story.) But in the end, Gilbert says, “I think [Samsung] took this very seriously and wanted to get these phones back.”
One reason for the success of the recall was the steady beat of publicity, both from news outlets and other sources. For instance the Australian Aviation authority banned Note7 phones from flights, and until Jan. 10 the agency required airline personnel to make announcements telling passengers not to bring the phones on planes.
Once the recall was put in place, 23 million text messages were sent to Note7 owners telling them to return the phones, Baxter said. When people plugged the phones in to charge, a message appeared advising them of the recall, and through a series of firmware updates, the company and its cellular partners reduced the functionality of the phones, until they were finally rendered inoperable.
Samsung officials said that they have instituted a new, eight-point program of quality assurance measures to help prevent future problems. And they plan to share what they’ve learned with others in the battery and mobile-phone industries.
