While Samsung is yet to divulge the details behind the batteries inside the Galaxy Note 7 exploding, a design engineering firm called Instrumental has done its own internal assessment on one unit of the handset and reached its own conclusion. According to the company’s CEO Anna-Katrina Shedletsky, the design of the Note 7 compressed the battery even during regular use that eventually led to the battery inside it exploding.

The compression put pressure on the battery which leads to the positive and negative cell layer inside it coming in contact with each other that ultimately leads to an explosion. This explains why not all the units of the Note 7 were exploding in regular use for most customers. These handsets were clearly not subjected to much use or external pressure due to which the positive and negative layers inside their battery had not come in contact yet.

What’s interesting is that there is evidence in the design of an intellectual tension between safety and pushing the boundaries. Samsung engineers designed out all of the margin in the thickness of the battery, which is the direction where you get the most capacity gain for each unit of volume.  But, the battery also sits within a CNC-machined pocket — a costly choice likely made to protect it from being poked by other internal components.  Looking at the design, Samsung engineers were clearly trying to balance the risk of a super-aggressive manufacturing process to maximize capacity, while attempting to protect it internally.

The CEO then speculates that due to rapid innovation and tight deadlines, Samsung did not put the final iterations of the batteries to be used inside the Note 7 under the same tests as the initial samples.

Interestingly perhaps, Shedletsky says that had the Note 7 units not suffered from exploding batteries, the design compression would have eventually lead the phone to separate due to the battery swelling.

And how could have Samsung avoided all this mess? By using a smaller battery.

Previous reports have also blamed the Note 7 fiasco on the 3500mAh battery being too big for the handset. Samsung is also expected to announce its own findings by the end of this year.