While we await Samsung’s report into what happened with the Galaxy Note 7 (promised by the end of the year), others aren’t waiting for the explanation for the Note 7’s notorious battery and self immolation issues. The team at Instrumental tore apart a Note 7 to try and find the answer for themselves, and what they found is a little disturbing.
It appears that Samsung’s design for the Note 7 is to blame, applying pressure to an already compacted battery. This would (and seemingly did) cause major issues if the battery swelled at all from being used, or if the phone’s body was compacted from being in someone’s pocket. These small changes to the dynamics of the Note 7 case could be enough to compress the battery to the point of failure immediately, or as we saw, after some time when it was least expected.
From the pictures above, you can see the maneuvering Samsung had to pull off to fit the battery into an incredibly small space; these ultra-fine tolerances — less than 0.1mm in some places — mean that there is no margin for error, and in fact, as good as no margin at all. All it would take is extremely minor changes to the shape or volume of the battery (and heat caused by charging could absolutely account for all that was needed) and the battery would immediately be put under pressure and potentially compromised.
That said, I’m not convinced that this is the only cause; smartphone manufacturers have been packing more into ever decreasing spaces for some years now, and if any company has the manufacturing finesse to pull this off, Samsung has to be close to the top of that very small list.
No, I don’t think the 0.1mm gaps are to blame, at least not by themselves. Almost certainly, what we saw with the Note 7 was a compound failure; defective battery cells which, perhaps, were more prone to swelling under stress, combined with virtually zero room to expand, causing compression on the battery, causing cell walls to fail, and thus the battery to short and ignite.
My speculation to one side, we should have the official answer soon enough.