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Updated: Samsung says this was what went wrong with the Note7 battery

By Alvin Soon - on 1 Oct 2016, 5:41pm

Samsung says this was what went wrong with the Note7 battery

Updated 15/9/16: Samsung provides more details about why the charging cutoff protection couldn’t prevent the affected phones from catching fire.

Updated 9/9/16: Samsung provides further details about the battery issue, pointing to a supplier fault.

First published on 7/9/16.

Samsung announced last week that they were going to replace all Galaxy Note7s that have been sold, due to reports of batteries bursting into flames while charging. This is a recall that is estimated to cost Samsung US$1 billion.

Yesterday, Samsung Singapore announced more details on how local users can exchange their existing Note7s for a new one, starting from 16th September. In the meantime, Samsung can provide Note7 owners with a loan phone (subject to availability) from now until they get their Note7 replacements.

Galaxy Note7 owners can call 1800-SAMSUNG for further assistance, that’s 1800-7267864.

As to what caused the batteries to explode? According to Samsung, the anode-to-cathode came into contact to cause the overheating:

“Based on our investigation, we learned that there was an issue with the battery cell. An overheating of the battery cell occurred when the anode-to-cathode came into contact which is a very rare manufacturing process error. We are working with multiple suppliers to ensure that a rigorous inspection process is conducted to ensure the quality of our replacement units and we do not anticipate any further battery issues.”

The anode and cathode lie on opposite ends of a lithium ion battery, with an electrolyte between them.

While Samsung’s latest explanation offers some more insight into how the Note7 devices caught fire, there are still some unanswered questions at this stage:

  1. Most batteries would have a protection circuit that cuts off charging once it senses temperature rising to an unusual degree. Why didn’t this work on the damaged Note7 units?
     
  2. Are all Note7s affected, which is why Samsung is recalling all of them, or are only certain batches affected, and Samsung is just playing safe? We know that the Note7 phones in China are not being recalled, for example, because the models there use a different battery.
     
  3. What if the Note7 customer doesn’t want to exchange his or her Note7 for another one?

Update: In response to our questions, we received the following reply from Samsung. It seems that the battery issue was caused by a faulty manufacturing from a specific supplier, and that all Note7 replacement devices will be equipped with batteries from other suppliers:

“The defect was revealed when several contributing factors happened simultaneously, which included sub-optimized assembly process that created variations of tension and exposed electrodes due to insufficient insulation tape.

“The coexistence of the above factors can result in a shorting path between the positive and negative layers inside the battery cell. It is a very rare manufacturing process error.

“In order to ensure the quality, we’ve stopped using the battery from the supplier in question. All Galaxy Note7 replacement devices will be equipped with the battery from other suppliers.

“We have worked around the clock with our supplier partners to ensure the highest quality manufacturing and quality assurance processes are in place. Based on a thorough inspection, we are confident that the battery issue has been completely resolved with the other supplier.”

Update: Samsung responds to our first question about why the protection circuit didn’t manage to prevent the affected Note7s from catching fire when charging:

“The Galaxy Note7 has a charging cutoff protection circuit which works when it reaches a certain temperature. In the reported incidents, it has been observed that an internal short circuit (ISC) occurred in a battery cell. Since this internal short circuit caused the overheating inside the battery, the protection circuit outside the battery could not prevent these incidents although it did cut off the charging or discharging externally.”

Read next: Everything you need to know about the Samsung Note7 battery saga.

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