Samsung unveils reason behind Galaxy Note 7 catching fire

PanARMENIAN.Net - Samsung Electronics said Monday, January 23 that tests of more than 200,000 Galaxy Note 7 smartphones found defects in two sets of batteries from two different manufacturers that made the devices prone to catch fire, The Associated Press reports.

Samsung's mobile division president, Koh Dong-jin, ruled out any problems with other aspects of the Note 7, either in its hardware or its software. He said Samsung would use what it learned from its investigations to improve lithium ion battery safety for the industry, though analysts questioned if the company had really gotten to the heart of the problem.

Samsung discontinued the Note 7 just two months after it was launched on August 2, in one of its worst product fiascos ever.

The company said 700 hundred researchers and engineers tested more than 200,000 devices and more than 30,000 batteries and replicated what happened with the Note 7 phones trying to pin down why some of the phones were overheating.

The Galaxy Note 7 featured one of the biggest battery capacities so far for smartphones at 3,500 mAh, or milliampere hour, which gave it the highest energy density of all Samsung's devices. However, Koh said Samsung and the outside inspectors found no evidence that the high energy density alone had made the phones prone to overheating.

Rechargeable lithium batteries are more susceptible to overheating than other types of batteries if they are exposed to high temperatures, are damaged or have manufacturing flaws. A highly technical explanation of Note 7 problems boiled down to the relatively large battery cells not fitting well into their pouches, with not enough insulating material inside.

In batteries by one manufacturer — likely Samsung SDI — used in the phones in the initial Note 7 recall, inspectors found damage to their upper corners. That, combined with thin separators and high energy density, caused the phones to overheat. The cell-pouch design of the battery did not include enough room to safely accommodate its electrodes — another flaw.

In other batches of batteries from a second manufacturer, presumably ATL, the researchers found welding defects and a lack of protective tape in some battery cells.

Recalls of the Note 7s began in September after reports emerged that some of the phones were overheating and catching fire. At the time, Samsung blamed a flaw in batteries from one of its two suppliers, without saying which manufacturer was to blame.

In October, Samsung dropped the phone for good after new Note 7s with different batteries issued as replacements also were found to be catching fire. It estimates the problems will cost it at least $5.3 billion through early 2017.

The company has recalled 3.06 million Note 7 phones. About 4 percent, or 120,000 units, of the recalled Galaxy Note 7, are still not returned.