While we wait for Samsung to publish the results of its official investigation into the Galaxy Note 7 fires and subsequent recall, a new teardown from Instrumental, completed with a fire extinguisher at hand, gives us our clearest look yet at what went wrong with the Note 7. In short, Samsung engineers didn’t allow enough internal space for the handset’s large battery, leading to a pressure build-up, short-circuit, and fires.
Many of the early reports about exploding Galaxy Note 7 handsets pointed to a major issue with the battery and a breakdown in the lithium ion battery’s electrolyte-soaked separators was thought to be the most likely cause of the fire, and this seems to have been the case. While it’s still possible that the manufacturing technique or a fault in Samsung SDI’s design is still partially responsible, the teardown reveals that excessive pressure on the battery is what is most likely to have cause the positive and negative layers of the thin polymer separator to touch, causing the fire. Put simply, the engineers crammed the battery in too tightly.