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Samsung has finally offered an explanation for last fall's smartphone meltdowns

Consumer Product Safety Commission Announces Recall Of Samsung's New Galaxy Note 7 Photo by George Frey/Getty Images

Last fall, Samsung was forced to recall millions of Galaxy Note 7 phones after dozens of consumers reported that they were spontaneously overheating. At a Monday morning press conference in Seoul (Sunday evening in the United States), the Korean giant announced the results of an extensive investigation. The company blamed the problem on defective batteries supplied by two battery manufacturers.

This isn’t surprising — Reuters reported last week that the report would reach this conclusion. The big question is whether Samsung can convince the world that it has diagnosed the problem precisely enough to ensure that it doesn’t happen again.

The answer matters because Samsung’s reputation has taken a beating as a result of the battery problems. Only a small minority of one model of Samsung phone have melted down. But given the risk that an overheating battery can lead to a fire, consumers still have every reason to be cautious.

Samsung claims that two different suppliers provided it with batteries with different manufacturing defects. That might sound unlikely, but Samsung also produced three different independent researchers who backed up their analysis.

If Samsung is right and the problem was caused by faulty batteries, then Samsung can avoid future problems by switching to another battery supplier. A lot is riding on whether that proves to be true.

Smartphone meltdowns are a safety hazard

Reports of Galaxy Note 7 smartphones spontaneously catching on fire started to appear within days of its August 19 released date. By the end of the month, at least 35 consumers had reported battery problems to Samsung.

Some of the reported problems were quite serious. Fox’s Phoenix affiliate reported on a man who said his Jeep was set on fire by a Galaxy Note 7 phone. Another customer in South Carolina reported a fire in his garage that he believed was started by a phone he had charging there.

Vox’s sister site the Verge has a nice explanation of the physics of the situation. Batteries are designed to store as much energy as possible, so they’re inherently volatile. Modern batteries are designed with careful safeguards to ensure that all that energy is only released in the controlled amounts required to power your phone. But a manufacturing defect apparently meant that in rare cases, the battery could discharge its stored energy very quickly and start a fire.

The inherent volatility of smartphone batteries means there’s always a (very small) risk of phones melting down. Over the years, there have been sporadic reports of smartphone meltdowns with phones from Samsung and Apple. In one 2015 case, a man said he had an iPhone catch on fire while it was in his pocket, causing severe burns.

But the dozens of Galaxy Note 7 batteries that malfunctioned within days of the phone’s release was a sign that there was something seriously wrong with this particular model.

Samsung struggled to address the problem

In early September, Samsung halted sales of the Galaxy Note 7. Concerned about people who had already bought the phone, the US Consumer Product Safety Commission issued a statement urging consumers to stop using the phones:

Samsung initiated a formal recall of the phones on September 15 and sent customers replacement Galaxy Note 7 devices. But by early October, it became clear that some of these replacement devices also had exploding batteries. Within days, Samsung gave up and cancelled the Galaxy Note 7 altogether, recalling all phones it had shipped.

In a particularly embarrassing development, the Federal Aviation Administration banned passengers from carry Galaxy Note 7 phones onto airplanes. Airlines were required to warn passengers not to bring the devices onboard, and Samsung had to set up booths in airports around the world so customers could exchange their phones for other, non-exploding, models.

All of this was particularly bad for Samsung’s brand. Samsung makes many different phone models, and only one of them had this serious manufacturing defect. But a lot of Samsung phone models have similar names — the Galaxy Note 7 is different from the popular Samsung Galaxy S7, for example — so it was easy for customers to get confused. And in any event, it’s never a good idea when your company’s name is appearing in headlines with phrases like “exploding batteries.”

Samsung is blaming battery suppliers

At a Monday press conference (Sunday evening in the United States), a Samsung spokesperson described the exhaustive process the company went through to investigate what caused the meltdowns. The company says it assigned a team of 700 engineers to conduct large-scale tests of 200,000 devices and 30,000 batteries. They set up huge racks of phones that they repeatedly charged and discharged in an effort to reproduce the problems experienced by customers.

Samsung tested thousands of phones simultaneously in an effort to reproduce the battery problems.

“We found that both fully assembled devices and batteries exhibited incidents at similar rates to those in the field,” said DJ Koh, president of Samsung’s mobile communications business. “This indicated that incidents were caused by the battery cells itself.”

The tricky thing about this explanation is that Samsung suffered from Note 7 battery fires with two different battery models. The original Note 7 devices came with batteries from one supplier, but Samsung switched to another battery supplier for the replacement models. Some of these also caught on fire.

Samsung’s analysis found that the two different batteries suffered from distinct but similar defects. At a fundamental level, a battery is just a bunch of layers of negative and positive electrodes separated by insulators. If these electrodes come into contact, it can lead to a rapid discharge of energy. Samsung found that the curved corner of the battery case for the first batch of batteries bent the electrodes and caused them to come into contact with each other, leading to a meltdown.

Samsung identified this problem with the batteries in September, leading them to believe that issuing new phones with a different model of battery would solve the problem. Unfortunately, the new batteries appear to have had a different defect: a problem with the welding process that created an internal short-circuit.

After Koh’s speech, he invited experts from three independent consulting groups to share their own findings, which dovetailed with Samsung’s. All of them agreed that separate manufacturing defects in the two different battery models led to the two sets of failures.

If Samsung is correct, this would be good news for them because it means they will be able to avoid future problems by switching to different battery suppliers and more carefully vetting the batteries they use.

That’s important because Samsung has a full pipeline of smartphones in the works for 2017. For example, the Galaxy S8, the next iteration of Samsung’s Galaxy S line, is expected to come out in the spring. If the problem with the Note 7 was its battery, and not a design flaw with other aspects of the phone, then putting a different battery in should avoid problems.

Of course, a big question here is why two consecutive batteries both had manufacturing defects. In its presentation, Samsung didn’t offer any particular theory for why two battery providers in a row supplied Samsung with defective batteries. But Koh told Cnet that the second manufacturer accidentally introduced the manufacturing defect in its rush to produce batteries for the recall effort.

Ultimately, the only way to find out for sure is to see if any problems crop up in batteries used in future Samsung models.

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