Samsung says Galaxy Note 7 fires due to battery short circuit
Negative electrodes and jelly roll issues.
In a press conference in Seoul today, Samsung revealed the result of its investigations into why its Galaxy Note 7 devices were so prone to catching fire.
DJ Koh, president of the mobile communications business at Samsung, said that comprehensive internal testing showed that the problems with the Note 7 were caused by the battery within the device. Specifically, the ultrasonic welding process used to attach the negative electrode in the upper right corner of the batteries and to the "jelly roll" connecting different battery components appeared to have caused problems and increased the likelihood of the batteries short circuiting internally.
Missing insulation tape and sharp corners on the connectors exacerbated the problem. External testing also suggested the high energy density of the batteries means that any short circuit was likely to cause bigger problems. Similar issues were encountered with both the original Note 7 battery and the ones used in replacement devices when the issues was first detected.
Samsung ran tests on 200,000 fully assembled Note 7s and more than 30,000 batteries, and built a dedicated testing facility to recharge and discharge batteries. It also hired external testing organisations to identify potential causes.
Samsung says it will improve its quality assurance processes in future to avoid similar issues, and has appointed a battery advisory group of academic experts to advise on future battery plans. It seems likely that it will not attempt such ambitious battery life goals for its next models.
While the Galaxy Note 7 was well reviewed upon launch, problems with the devices catching fire led to a permanent recall, with Samsung offering refunds to all Note 7 purchasers. To ensure that people wouldn't use the devices, Samsung rolled out system patches that cut down battery life and eventually made it impossible to make calls using the phones.
The recall has clearly had an impact on interest in Samsung's sales, and may ultimately impact its status as the biggest-selling Android manufacturer. Prior to the recall, it sold some 51,060 of the Galaxy Note 7 in Australia. Koh said that 96% of the 3 million Note 7 phones sold globally had been returned. finder.com.au research shows from August to September, brand intent for Samsung on our Mobile Phone Finder site dropped by almost a third. It moved from 32% of mobile comparisons involving Samsung devices to 23%, and steadily decreased to 19% in December.
Samsung's next device is expected to be the Galaxy S8. It's widely assumed that this will launch at Mobile World Congress in Barcelona in February next month, though some reports have suggested it won't go on general sale until April.