Initial conclusions indicate an error in production that
placed pressure on plates contained within battery cells.
That in turn brought negative and positive poles into
contact, triggering excessive heat. Samsung however
stressed that it needed to carry out a more thorough
analysis to determine “the exact cause” of battery damage.
I seem to recall an article not too long ago (perhaps here on HN?) that analyzed the Note 7 battery failures; their conclusion was along the lines that the phone was designed too slim for the battery manufacturing tolerance.
So in some percentage of the phones the battery will be under constant mechanical pressure because the battery is slightly bigger than the space allocated for it. This pressure may eventually force the plates inside the battery into contact with each other, or at least close enough to cause leak currents and overheating.
> Does turning them off prevent them from catching on fire?
Not necessarily. Assuming the cause is as Samsung describes it, it can happen even with the phone turned off. But overheating to the point of thermal runaway is more likely at higher voltages (during charging, or with fully charged battery), and probably more likely during high current drain (aka using the phone).
For more technical details, I suggest the Electrical Engineering Stackexchange.
Judging by the fact that the new version of the phone may still be catching fire, we may not know what the cause is. If Samsung had accurately diagnosed the problem in the first place then this incident probably wouldn't have occurred.
According to the article it said that he powered down the phone and put it in his pocket before it started smoking. Maybe it started combusting when he powered it off.
Nevertheless I would be freaking out if that happened mid flight.
I seem to recall an article not too long ago (perhaps here on HN?) that analyzed the Note 7 battery failures; their conclusion was along the lines that the phone was designed too slim for the battery manufacturing tolerance.
So in some percentage of the phones the battery will be under constant mechanical pressure because the battery is slightly bigger than the space allocated for it. This pressure may eventually force the plates inside the battery into contact with each other, or at least close enough to cause leak currents and overheating.
> Does turning them off prevent them from catching on fire?
Not necessarily. Assuming the cause is as Samsung describes it, it can happen even with the phone turned off. But overheating to the point of thermal runaway is more likely at higher voltages (during charging, or with fully charged battery), and probably more likely during high current drain (aka using the phone).
For more technical details, I suggest the Electrical Engineering Stackexchange.
http://electronics.stackexchange.com/a/230164/64021