Your opinion on Samsung Note 7 battery explosions

bestsystem

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Under what condition would cause Lithium polymer cell manufactured by such a reputable company to explode?
 

radellaf

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Under the condition that the separator failed, despite quality engineering and best efforts at flawless manufacturing?

I don't think they really know what it was, but something was probably physically wrong with the batteries. Or the charge circuitry, perhaps, but I doubt that. Cathode and anode weren't separated at some point, and foomp! Did they ever really "explode"? All I saw photos looked like fire damage. There's nothing in a LiPo or phone to really contain pressurized gas, and the battery materials can only burn so fast.

There's a nail penetration test video of a laminated lithium cell that would be worst case. I guess it is sort of an explosion. Rapid inflation of the LiPo bag and burning, really. If popping a balloon full of hydrogen counts, then this would: https://youtu.be/nUg7cDbRBo0?t=1m

I don't know if the Note 7 had particularly fast charging, but that seems like a risk factor along with light & thin. Unintentionally "flexible" phones are going to bring out battery defects that might have been silent if not heated and squished repeatedly.

Article about it: How Samsung's phone design caused battery problems

Samsung, in one public announcement, acknowledged that "an overheating of the battery cell occurred when the anode-to-cathode came into contact, which is a very rare manufacturing process error."

"Energy storage is nature's abomination,"
"The more of those lithium ions you have in a very close proximity to each other, stored up, the more trouble you could be in. That's a very energetic environment."
"They're reaching a little bit when they make the batteries. Whenever anything new is mass produced that contains a flammable liquid, you have to cross your fingers a little bit."
-- Jay Whitacre, energy-material scientist and engineering professor at Carnegie Mellon University.

Whitacre was also quoted in an earlier article: Why Hoverboards Keep Exploding. Those were blamed on defects and abuse of batteries made by non-reputable-company batteries, but even a good company can have problems. Just, less often.

"We've got an unstoppable force meets an immovable object. The unstoppable force is that I want more energy in my phone so it lasts all day. The immovable object is the more energy I put into these thin layers, the more likely my phone is going to blow up on an airplane."
"You want price, performance and safety? You get to pick two."
-- Matthew Nordan, energy investor, MNL Partners.

"When you start putting increasingly more energy in smaller and smaller packages, that's tricky in terms of safety. Because it starts to sound like an explosive device, which tends to be high energy, small package."
"The lithium-ion battery for electric vehicles is projected to be $90 billion. Batteries are, in a sense, becoming the new oil."
-- Steven Visco, guest scientist at the Lawrence Berkeley National Laboratory, CEO of Polyplus.
 
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FRITZHID

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Under the condition that the separator failed, despite quality engineering and best efforts at flawless manufacturing?

I don't think they really know what it was, but something was probably physically wrong with the batteries. Or the charge circuitry, perhaps, but I doubt that. Cathode and anode weren't separated at some point, and foomp! Did they ever really "explode"? All I saw photos looked like fire damage. There's nothing in a LiPo or phone to really contain pressurized gas, and the battery materials can only burn so fast.
I don't know if the Note 7 had particularly fast charging, but that seems like a risk factor along with light & thin. Unintentionally "flexible" phones are going to bring out battery defects that might have been silent if not heated and squished repeatedly.

Article about it: How Samsung's phone design caused battery problems

Samsung, in one public announcement, acknowledged that "an overheating of the battery cell occurred when the anode-to-cathode came into contact, which is a very rare manufacturing process error."

"Energy storage is nature's abomination,"
"The more of those lithium ions you have in a very close proximity to each other, stored up, the more trouble you could be in. That's a very energetic environment."
"They're reaching a little bit when they make the batteries. Whenever anything new is mass produced that contains a flammable liquid, you have to cross your fingers a little bit."
-- Jay Whitacre, energy-material scientist and engineering professor at Carnegie Mellon University.


"We've got an unstoppable force meets an immovable object. The unstoppable force is that I want more energy in my phone so it lasts all day. The immovable object is the more energy I put into these thin layers, the more likely my phone is going to blow up on an airplane."
"You want price, performance and safety? You get to pick two."
-- Matthew Nordan, energy investor, MNL Partners.

"When you start putting increasingly more energy in smaller and smaller packages, that's tricky in terms of safety. Because it starts to sound like an explosive device, which tends to be high energy, small package."
"The lithium-ion battery for electric vehicles is projected to be $90 billion. Batteries are, in a sense, becoming the new oil."
-- Steven Visco, guest scientist at the Lawrence Berkeley National Laboratory, CEO of Polyplus.
Nuff said. [emoji106]
 

The_Driver

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Here is what I have heard from someone who works in the battery business:
Samsung tried to make the battery smaller in these phones by using a pouch-type Li-Po cell for the first time in such a phone. Until now the batteries have had hard, outer enclosures.
The problem is that when charged, Li-Po batteries expand a tiny bit. The standard phone batteries in most phones have enough additional space inside their enclosures to account for this expansion.
Samsung supposedly made the mistake of forgetting to include this extra space.
When charged the battery basically crushes its self and that's when all the bad stuff happens.

The reason for all of these problems (in my opinion): the constant drive of the manufacturers to make the new phones even thinner each year. In my opinion this does not make any sense. A 7mm thin phone is not easier to hold than a 9mm thin phone. Both are "thin". It also dosn't really make a difference in ones pocket if the thickness is 7 oder 9mm (the actual screen and bezel size is much more important in this regard). It does make it more problematic to put in a large enough battery for the large, power-hungry displays that everybody wants. The manufacturers try to overcome this problem by resorting to drastic measures like raising the voltage of the batteries to >=4.3V, which generally reduces their cycle life, implementing extreme fast-charging solutions (added danger, complexity and cost) and what led to Samsungs problems above.

It would be much easier and safer to take a current phone design, make the phones case 2-3mm thicker and put in a standard hard-case battery that runs down the entire backside of the phone with a much larger capacity compared to current phone batteries. There would be no need for any of the things mentioned above and people who don't need the additional runtime could use a special mode where the battery is never completely discharged and never fully charged (>=4V). This would greatly increase the cycle life of the batteries. Tesla does this in their cars.
 
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vadimax

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I guess this is a situation when tolerances were so tight that they managed to keep them in test environment, but mass production deviations were enough to pass the limit.
 

The_Driver

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Here is a picture of the inside of the phone from ifixit. It's easy to see that the battery is very small compared to the size of the phone.
 

Capolini

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I do not know all the technicalities as to why they caught on fire.

From a visual perspective,to me, that battery is NOT very small compared to the size of the phone!It covers at least 25% of the area of the phone. Maybe 35%.

It is hard to tell how wide the phone is in comparison to the battery because of the camera angle[shot]
 

radellaf

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make the phones case 2-3mm thicker and put in a standard hard-case battery that runs down the entire backside of the phone with a much larger capacity...use a special mode where the battery is never completely discharged and never fully charged (>=4V). This would greatly increase the cycle life of the batteries.

Dunno about hard cases being worth the space but I do love that line about how we should be so happy to get a little bit more battery life on the iPhone 7 with some credit to the space saved by removing the (I think mandatory) headphone jack. I'm thinking, y'know, make it 1mm thicker, and wow could the battery last longer. 2-3mm more and, it might even get people to quit complaining about battery capacity altogether. The iPhone 4S (9.3mm) was as thin as I'd ever need, though a little lighter would have been great. The iP 6 is 6.9mm, so that's 2.4mm to spare right there. The Note 7 is 7.9mm and much bigger in the other directions. 1.4mm to spare, at least, for a return to a sane thickness.

Not only would the cell have been squished when expanded in the chassis as-is, but I have to imagine any pressure on the front or back could easily cause another 0.1-0.3mm of squish. Maybe more.

Lenovo laptops have an option to limit charge to 80% instead of 100%. I so wish I could do that on my iPad and MBP. The phone, maybe not all the time, but that too. I think customers would demand that feature if they had any clue how much longer the batteries would keep that 80% capacity, instead of being degraded down to 80% by a couple years running at 4.2V or higher charge.
 

Overclocker

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i've had these hundred or so 18650 cells since last year. they were from a company i've never heard of before: ATL Amperex. they've just been sitting on a shelf...

then suddenly this Note7 fiasco just burst into the scene (pun intended) and i was surprised to see Amperex in the news! apparently there were two sources for the Note7 batteries. Amperex supplied the cells for phones intended for the chinese market. Samsung SDI supplied the rest.

guess what, the Amperex cells weren't exploding

i'll soon be building these Amperex cells into a new electric motorcycle :)
 

NoNotAgain

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I'm an iFixit kinda of guy. Been replacing my own batteries in iPhones since the iPhone 4 when Verizon first started selling Apple products.
The batteries used by Apple are prismatic batteries, not hard cased.

There's more to the Note 7 defects than batteries, otherwise Samsung would have just reduced the thickness on new batteries instead of cancelling the entire phone.

They've got charging circuit problems. If it were just a battery issue, handling cases of batteries in the supply chain would have caused fires in transport.
 

Dr. Mario

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It wouldn't matter what battery brand used in Note 7, any batteries, including those from Amperex, will still blow up if intentionally overcharged.

Why? I am pointing the finger at the battery management system. It's obvious Samsung screwed up badly here. Any mistakes in the motherboard design and / or second-stage bootloader (they make their own ABOOT image) will inevitably lead up to a serious electrical problem.

I am all for LiFePO4 pouch cell, as it's actually proven hard to set on fire, but the manufacturers are not always honest, they'd rather keep on using Lithium : Nickel-Magnesium Dioxide cells (or even worse, Lithium : Cobalt Oxide cells) for their much longer runtime. But even with electrical faults in Note 7s, motherboards may catch on fire instead of the battery if you are to use LiFePO4 cells in them.
 
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TinderBox (UK)

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What was the maximum charge voltage for the N7 battery cells, they have been using 4.35volts for a few years, They did not go beyond this on the N7 did they.

John.
 

Dr. Mario

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Given they have tried to cap the charging to 60%, I'd think so. Static charging (done via cheap, low part count Lithium-ion battery charger chip) usually pump the batteries with 4.4 Volts, and gets switched off once current reaches the shutdown threshold of the particular charger chip (probably it's actually 4.2 Volts as the cheaper Lithium-ion charger chip is literally a linear voltage regulator).

Smarter, firmware defined charger like the ones used in the recalled (and now cancelled) Note 7, dynamically track the charging voltage with the battery's state of charge and shuts off once it hits the desired charging voltage (4.2 - 4.35 Volts) and amperage drops to charge halt threshold (usually around 200 mA to the cell) - all done by the software (either first or second stage bootloader - since having studied how Qualcomm bootloader works, I'd say it's the latter).
 
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