Independent Galaxy Note 7 analysis theorizes that too-tight battery led to inevitable failures

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An independent analysis of the Galaxy Note 7 suggests that Samsung engineered the device too tightly, and failed to give the battery any buffer between it and the surrounding metal of the case, which lead to the conflagrations experienced by more than 100 users in the summer and early fall.




As a result of the too-tight tolerances, the slightest expansion of the battery or contact between the battery and the enclosure from external forces appears to inevitably impinge on the battery's membrane, or compress it so tightly that the positive and negative terminal plates inside the battery would touch. The resulting energy discharge appears to be what caused the fires in the device.

However, the engineers don't believe that choices that led to the design flaw were all by accident.

"The battery also sits within a CNC-machined pocket -- a costly choice likely made to protect it from being poked by other internal components." said Instrumental regarding the battery mount. "Samsung engineers were clearly trying to balance the risk of a super-aggressive manufacturing process to maximize capacity, while attempting to protect it internally."
"They shipped a dangerous product." - Instrumental on the Galaxy Note 7
The machined pocket was intended to protect the relatively softer battery membrane from the rough edges of the circuit board. As a result of inclusion, the widest gaps between the battery and the edge of the case was 0.5mm, with one part of the battery nearly in contact with the battery frame, measured at less than 0.1mm.

The disassembly also showed that there was no "ceiling" above the battery at all, with no apparent swell developed in the sacrificial unit. In the iPhone, and similar, safe, devices, there is at least a 0.5mm ceiling above the battery to allow for the normal expansion of the battery over time.

Instrumental believes that had the devices not been totally recalled, nearly all the phones would have been burst open by battery swell given enough charge and discharge cycles.

While the engineers performing the tear-down weren't present during the design process, they theorize that the battery manufacturing process was changing during the development of the Galaxy Note 7, and the newest versions that originally shipped with the phones "weren't tested with the same rigor" as sample phones built before mass-manufacturing began.

"In this case, Samsung took a deliberate step towards danger, and their existing test infrastructure and design validation process failed them," claimed Instrumental. "They shipped a dangerous product."

Still no solid data from Samsung

Samsung has not as of yet publicly declared what the engineering problem with the Galaxy Note 7 was. The company has not said much more about the issue than it said when it stopped production in October of the device, and issued a world-wide recall of the phone.

"We recently readjusted the production volume for thorough investigation and quality control, but putting consumer safety as top priority, we have reached a final decision to halt production of Galaxy Note 7s," Samsung said in the October recall statement.?"For the benefit of consumers' safety, we stopped sales and exchanges of the Galaxy Note 7 and have consequently decided to stop production."

After the first wave of failures, employees involved in the post-recall testing claimed that they were required to keep communications about the evaluation process offline, with e-mails and other accountable forms of communication forbidden. Samsung allegedly feared lawsuits and subpoenas as a result of the fires, leading to the drastic restrictions on staff.

Samsung drew complaints from the CPSC in how it handled the initial "voluntary recall" of the device. Samsung reports that it is "fully cooperating" with the CPSC at this time to work out what happened, and to ensure that it doesn't happen again in other devices.

AppleInsider has learned that unreturned Galaxy Note 7 devices are still causing fires, with a CPSC employee telling us that there have been "more than 10" fires since the full recall, all caused by hold-outs refusing to return the devices.

In late November, Samsung issued a statement declaring that the Galaxy S7 family was safe, after a handful of device fires tied to the S7 and S7 Edge were reported to media.

Comments

  • Reply 1 of 15
    calicali Posts: 3,495member
     Independent research because Samsung still doesn't give a sh** about their customers. 
    jbdragonwatto_cobrajony0pscooter63
  • Reply 2 of 15
    This makes the design of replacement phones even stranger. This was suspected as a cause at the time, so why did they not use a smaller battery in the replacement units?
    Solijbdragonwatto_cobrajony0
  • Reply 3 of 15
    Interesting comment about over time all phones may have failed. Without knowing the issue, Samsung knew there was a growing issue or they would not have recalled considering how costly it is to recall devices. 
    Solinetmagewatto_cobrajony0pscooter63
  • Reply 4 of 15
    webweasel said:
    This makes the design of replacement phones even stranger. This was suspected as a cause at the time, so why did they not use a smaller battery in the replacement units?
    Rush-job, note7's shipped with one of two different batteries, they wrongly assumed the cases were all linked to one type of battery and switched to the other for the refurbs. both batteries were the same size so it made no difference. Total balls up from start to finish to be fair.

    Samsung should be coming clean with this info, as it will put owners of other samsung devices minds at rest knowing it was a design fault restricted to the Note7 phone only and not a general samsung phone problem. Then again, they probably don't want to admit such a school-boy error.
  • Reply 5 of 15
    Rayz2016Rayz2016 Posts: 4,518member
    webweasel said:
    This makes the design of replacement phones even stranger. This was suspected as a cause at the time, so why did they not use a smaller battery in the replacement units?
    I don't think they knew what the problem was before the replacements went out. They thought  swelling batteries was the problem so they put new batteries in the same phone, with the same tight fit. 


    edited December 2016 netmagewatto_cobrapscooter63
  • Reply 6 of 15
    SoliSoli Posts: 8,433member
    cali said:
     Independent research because Samsung still doesn't give a sh** about their customers. 
    Samsung surely looked into this as this issue cost them billions in lost revenue.
  • Reply 7 of 15
    SoliSoli Posts: 8,433member
    webweasel said:
    This makes the design of replacement phones even stranger. This was suspected as a cause at the time, so why did they not use a smaller battery in the replacement units?
    Smaller in height, width, and/or thickness, and/or smaller in Watt hours?
  • Reply 8 of 15
    holyoneholyone Posts: 377member
    Wow galaxy even ugly on the "inside"
    watto_cobraredgeminipa
  • Reply 9 of 15
    SoliSoli Posts: 8,433member
    Is tolerance the proper word choice here? If this independent study is accurate, Samsung had poor tolerance if they were allowing their battery to be placed to closely to other components. It's like putting in a wood floor and not having enough space along the wall for expansion, which will cause your beautiful wood floors to buckle after a fashion.
    jbdragon
  • Reply 10 of 15
    melgrossmelgross Posts: 31,267member
    It took them this long to find what I've been saying everywhere since it first happened. Good work!
    watto_cobrapscooter63
  • Reply 11 of 15
    SoliSoli Posts: 8,433member
    melgross said:
    It took them this long to find what I've been saying everywhere since it first happened. Good work!
    What we say and what can be proven with thorough testing are very different things.
    StrangeDays
  • Reply 12 of 15
    glynhglynh Posts: 128member
    AppleInsider has learned that unreturned Galaxy Note 7 devices are still causing fires, with a CPSC employee telling us that there have been "more than 10" fires since the full recall, all caused by hold-outs refusing to return the devices.
    It's bad enough that Samsung fucked up but the scary thing for me is the above statement.

    Why would anybody in their right mind want to hang on to a device that could spontaneously combust with life-threatening consequences?

    What if the 'shit-for-brains hold-out' decided to pack their phone in check-on luggage to save the embarrassment & possibility of the device being confisticated from them in the cabin of an aircraft?

    After hearing the cabin crew go through the normal safety procedure and adding that Samsung Galaxy Note 7 should be turned off and not checked in when this fiasco went live I'm sat onboard the aircraft looking round wondering who might have done that.

    No one would likely put their hand up following the announcement and say 'Oh hang on a minute I've packed mine in my checked luggage' now would they?

    It might not even be their phone and by that I mean they could have picked up one cheap when visiting another country for themselves or a present for a friend and packed it in their suitcase.

    Not sure if baggage X-Ray would have the resolution to distinguish the GN7 from similar devices or not?

    Scary thought and the fact that there are some morons out there holding on to them despite still catching fire doesn't bear thinking about.
    watto_cobra
  • Reply 13 of 15
    melgrossmelgross Posts: 31,267member
    sog35 said:
    No way the problem is this simple.

    Samsung would have figured it out in a couple of hours.

    The problem is much, much, much deeper. We are talking about software
    Nope. It's this simple. They heard the new iPhones had better battery life. The old 6s series already had slightly better battery life. So they switched to a larger battery. This is known. But the phone was designed for the  (literally) smaller battery. The space for the battery was designed for the smaller, thinner, battery. The bigger battery fit, but just barely.

    when a battery is used, it heats up and expands slightly. Normally the width of the battery is far greater than the thickness. So it expands slightly, becoming thicker. The normal slot for the battery accommodates this expansion. But the new battery, being thicker, had less room to expand. Because of that, two things happened. One is that the battery was restricted from expanding fully when heavily used, or charged, particularly quick charged. So it also tried to expand through the edge, which would balloon out.

    the result was that the battery would not expand enough, and so would slightly crush the internals of the battery itself. After a few of these cycles, the elements inside would short. It would then balloon out through the open edge, the edge would rapidly burn from the hot gasses (about 2,000 degrees), and we know what happened afterwards.

    no software is involved. It's a simple engineering problem of a mechanical nature. Companies make mistakes like this all the time. Figuring it out is difficult. There's a reason for that.

    the reason is that only a small percentage of batteries caught fire. There are tolerances in manufacturing. Those tolerances, like most everything else, fit a normal curve. The goal is the very top of the curve. But that's rarely achieved. We have two parts that work together, the battery, and the slot it fits into. With the proper battery, the trailing edges of the curves never meet. That is, the thinnest slot is always thick enough so that the thickest battery isn't too thick. Also, the thickest battery is never too thick for the thinnest slot.

    but when they went to a thicker battery, that safety margin disappeared for a very few batteries. In those cases, the thickest batteries were slightly too thick for the thinnest slots. The normal curves crossed with the thickest batteries and the thinnest slots. In the worst cases, we saw what happened when specs are not met. It was difficult to find this problem because almost all the batteries were just thin enough. The ones that weren't, blew up, and couldn't be measured. They needed to check a huge number of phones until the statistics added up. And now they have.

    i'd like to point out that the head of the Consumer Product Safety Commission here said that the batteries were too thick some time ago, shortly after I began saying it. So there wasn't a lack of people who figured it out back them.
    watto_cobrapscooter63
  • Reply 14 of 15
    Soli said:
    webweasel said:
    This makes the design of replacement phones even stranger. This was suspected as a cause at the time, so why did they not use a smaller battery in the replacement units?
    Smaller in height, width, and/or thickness, and/or smaller in Watt hours?
    Yes.
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