Updated: January 24, 2017 9:06:15 am
Samsung Galaxy Note 7 fires and explosions were caused by defects in the battery, and the company has now released details of its investigation. The South-Korean technology conglomerate has also come up with an eight-point safety measure for its smartphone batteries in order to ensure that such a scenario doesn’t happen again. According to the company, leading industry groups namely UL, Exponent and TUV Rheinland also conducted their own investigation into this issue.
Further, Samsung now has a Battery Advisory Group, which consists of external advisers, academic and research experts around this issue. This includes Clare Grey who is Professor of Chemistry at University of Cambridge, Gerbrand Ceder who is Professor of Materials Science and Engineering at UC Berkeley, Yi Cui who is Professor of Materials Science and Engineering at Stanford University and Toru Amazutsumi, CEO of Amaz Techno-consultant.
“We look forward to moving ahead with a renewed commitment to safety. The lessons of the past several months are now deeply reflected in our processes and in our culture,” the company said in a statement.
For those who remember, Samsung had to issue two recalls for the Galaxy Note 7. The first one came in September, and then new phones were launched to replace these units. Samsung then had to pull the plug on the second batch of Galaxy Note 7 phones in early October.
After the first recall, Samsung had blamed faulty batteries, and then relied on a different manufacturer, but evidently the problem was not plugged in the second case either. It should be noted that Samsung has not yet confirmed the names of the manufacturers for the batteries. However, the US Consumer Product Safety Commission said Samsung’s own SDI battery unit was the supplier in the first case.
So what exactly caused the problems with the Galaxy Note 7’s battery? Here’s a detailed look at Samsung’s explanation, along with ones given by the independent investigating agencies.
Battery A issues
The investigating team found there was an issue with the design in battery A. The problem: Not enough room to allow for the expansion of its electrodes, which happens during the normal charge and discharge cycle of the battery.
Samsung own explanation is that “the negative electrode was deflected in the upper right corner of the battery,” which is an abnormality in the design. In a normal battery, the positive and negative electrodes are properly separated, and the negative electrode is not deflected nor is it touching the positive electrode.
An additional contributing factor, according to Samsung was the tip of the negative electrode was incorrectly located, resulted in short-circuiting of the battery.
In another detailed presentation put out by independent agency Exponent, the report highlights that the thermal failure in battery A was caused due to “unintended damage to the negative electrode windings consistently in the corner of the cell.” This report too blames a design flaw in the cell pouch for this and says there was not enough space “accommodate the electrode assembly,” thus increasing risk of failure.
Another investigation by UL, which is a global independent safety science company, found signs of “internal short circuit (ISC) at the upper right corner of the cells from 6 damaged devices.” This report also found a pattern of deformation at upper corners of the battery. The agency blames factors in battery manufacturing and assembly for the failure of the Note 7.
Samsung relied on a different manufacturer for the second batch of battery when new units of the Note 7 were sent out to replace the original ones. In this case, it looks like there were problems with the manufacturing quality and safety norms were ignored.
Samsung’s own report says there were “high welding blurs on the positive electrode,” which caused damaged to the insulation tape and separator, and once again the positive electrode was touching the negative one, resulting in the short-circuit. Additionally a number of batteries were missing the insulation tapes, which made the problem worse.
The report by Exponent blames “welding defects” and says some cells had no “protective tape over the positive electrode tab,” which resulted in the failure and short-circuiting. UL’s analysis also blames welding defects in the battery, along with poor alignment and inconsistent shape of insulation tapes for the problem.
So what is Samsung doing to ensure this doesn’t happen again?
Samsung has announced an enhanced 8-Point Battery Safety Check for safety of batteries used in their phones. The list includes enhanced durability, visual inspection, X-Ray Test, disassembling test. New measures include Charge and Discharge Test, TVOC Test and Accelerated Usage Test.
The Total Voltage Organic Compound test ensures there’s no leaked of the volatile organic compound, while the Accelerated Usage tests compares all possible consumer usage scenarios.
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