Samsung's Note 7 battery holds an impressive 3,500mAh, despite its slim profile. "Imagine if you had a toilet paper roll and it wasn't packed tightly," says Sadoway. With the same size roll, you'd run out a lot quicker. At first, Sadoway has two theories: perhaps Samsung simply pressed so hard that the positive and negative terminals poked right through the separator and managed to touch. Or perhaps it's the sponge-like separator itself that got squished. Normally, says Sadoway, the separator allows the liquid electrolyte to pass through pores connecting the negative and positive sides of the battery, even as it keeps the two terminals separate. "If they press really hard, they constrict the pores, the resistance goes up and you generate more heat," says the professor.
But there's another, turquoise blue sea turtles in ocean iphone case more interesting theory: perhaps Samsung's batteries are skewering themselves on their own tiny spears, When Sadoway explains these theories, one thing doesn't seem to add up, Today's cell phone batteries generally charge faster (and get hotter) when they're first plugged into the wall, not at the end when they're trickle-charging the last few percent to reach their maximum capacity, But these Note 7 phones didn't explode right away, In practically every reported instance of a Note 7 catching fire or exploding, it happened after the phone was plugged in and left charging, sometimes overnight..
Then, there's the little matter of how Samsung plans to make these phones safer -- by issuing a firmware update that keeps the Galaxy Note 7 from charging to more than 60 percent of its full capacity. How could that possibly help, if things heat up the moment a phone is plugged into the wall?. Sadoway has a theory -- albeit one without proof. What if only part of the battery was squished improperly, so that the phone couldn't tell when it was 100 percent charged, and kept on charging the cell?. When lithium ion batteries are continually trickle charged, the lithium ions can start to cover the surface of the negative contact in a coating of lithium metal through a process called "plating." And in extreme conditions, that lithium metal can form tiny spikes (called "dendrites") that can poke right through the separator, creating -- you guessed it -- a short circuit.
That would seem to line up with the "variations in tension" Samsung says it found inside the defective battery cells, "My guess is by backing off to 60 percent charge, they'll be well below the threshold where these things happen," says Sadoway, "Imagine we're trying to fill our gas tank, we don't have a really good regulator, and we don't want to spill the gas all over our shoes, We want to make sure we're cutting off the flow well before this thing turquoise blue sea turtles in ocean iphone case gets to overflow conditions."Samsung didn't respond when asked for comment on the theory..
These are just a few theories based on one battery expert's remote analysis of Samsung's initial findings. We don't have the whole truth yet, and the truth is what Samsung and government agencies around the world are looking for as we speak. Just one mystery: why the replacement batteries might also be exploding. We'd confirmed that the replacement Notes had a battery from a different supplier -- the manufacturing issues were found in batteries built by Samsung SDI -- but maybe that wasn't enough.
