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posted by martyb on Tuesday January 24 2017, @11:11AM   Printer-friendly
from the found-after-a-battery-of-tests dept.

http://www.npr.org/sections/thetwo-way/2017/01/22/511134871/samsung-pins-blame-on-batteries-for-galaxy-note-7-meltdowns

In a packed press conference at its offices in southern Seoul Monday, the world's biggest smartphone maker again apologized to customers around the world for the bungling of its product release. Phones were initially recalled and replaced, but the replacement devices also began to catch fire.

Presentations at the announcement by outside investigators backed up Samsung's findings, which indicate batteries from supplier A were shorting because of a design flaw or in some cases a lack of insulation tape. And batteries from supplier B — which were issued in the replacement phones following the initial recall — were catching fire because of a separate manufacturing defect.

A story at Ars Technica provides additional information:

[Continues...]

In its report, Samsung refers to the battery manufacturing partners in generic terms—possibly to help those partners save face. This "Battery A," "Manufacturer A" obfuscation really won't fool anyone who is paying attention, since Samsung identifies "Battery A" as "from the first recall," and the first recall exclusively targeted batteries made by Samsung SDI.

For the Samsung SDI batteries, Samsung's investigation determined that the corner of the battery casing was too small, which resulted in the negative electrodes in the corner of the battery being bent. This made it easier to short-circuit the battery and cause a "thermal runaway" situation where the battery explodes or catches fire. Exponent, one of the consulting companies in Samsung's investigation, said that this "unintended damage was present in all of the cells examined by Samsung and Exponent." This means that in the first round of Galaxy Note 7s, nearly 100 percent of devices were defective. (Think of that as a one-more-time warning for the 4 percent of Note 7 customers who still haven't returned their devices.)

Samsung also identified an "additional contributing factor" with Battery A: the negative electrodes were too long, which led to them being bent in the curve on the long side of the battery.

With the first recall underway, "Battery B"—which previous reports said was manufactured by ATL—was used in all the replacement Galaxy Note 7s. Battery B didn't have any of the Battery A defects; it had a defect all its own. When connecting the positive tab to the battery, "Manufacturer B's" welding process—which Exponent called "poorly controlled"—created high, sharp welding burrs. Normal expansion and contraction of the battery electrodes during charging and discharging caused the welding burrs to scrape against the insulation between battery layers. Eventually this scraping could penetrate the insulation and short out the battery, causing fireworks.

Another "additional contributing factor" to the failure of Battery B sounds rather alarming: some batteries were missing insulation tape. The tape helped reinforce certain trouble spots, and apparently ATL forgot to attach it to many units.

The story goes on to report that Samsung has now instituted an 8-point battery safety check as part of its manufacturing process.


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  • (Score: 3, Insightful) by WillR on Tuesday January 24 2017, @02:44PM

    by WillR (2012) on Tuesday January 24 2017, @02:44PM (#458098)
    At best, they would be equally safe - they would be made by a "ghost shift" on the same line and have the same flaw as the genuine Samsung batteries. At worst, they would be factory rejects from the same line, with some detectable flaw in addition to the hidden one in the genuine battery.
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