TOKYO -- Though Samsung Electronics declared that battery defects caused its Galaxy Note 7 smartphone to catch fire, the factors that add up to such combustion are often difficult to determine.
Fires in lithium-ion batteries are frequently started by chemical reactions, but these may owe to a complex interplay of factors, both internal and external. Increases in battery capacity and other technical aspects add to the challenges facing investigators.
Sony encountered the problem in 2006 when its batteries used in personal computers caught fire. A report on a joint investigation by the company and third parties fingered metal particles contaminating the batteries. The particles increased the likelihood of combustion when the batteries were intermittently exposed to higher voltages than they were designed for in rapid-charging mode, according to the report. But some PC makers disputed this. Sony shouldered recall costs.
In 2013, lithium-ion batteries used in Boeing 787 jetliners caught fire. The aircraft builder modified the battery system to prevent a repeat of the phenomenon, known as thermal runaway. But the reason that the batteries, supplied by Japan's GS Yuasa, overheated in the first place was never clearly established.
With the Samsung Note 7 scandal, the South Korean company clearly blamed defective batteries for the fires but also said it has no intention of seeking damages from the suppliers.
Japan's TDK, parent of a Hong Kong company said to be one of the suppliers, said it would not comment on a specific customer. As in past cases, the lack of clarity over where responsibility lies suggests behind-the-scenes bargaining between manufacturer and suppliers.