4 ms·

My question is why wasn't their QA process catching this in the factory? Especially after the first recall. It seems like they didn't bother making a special ef

My question is why wasn't their QA process catching this in the factory? Especially after the first recall. It seems like they didn't bother making a special effort to verify the second battery source was producing good batteries. (I honestly have no idea, I'm not involved in manufacturing.)

owenversteeg 10y ago
Samsung SDI is separate enough from the smartphone makers that I'd guess it just wasn't prioritized as much as it should have been. 2.5 million phones were sold, at 14 watt hours per battery that means that the Note 7 batteries would only be a few percent of their total production (35 MWh of Note 7 batteries produced.) Catching problems like this can be pretty tricky and at the end of the day it's also possible that a few people getting lazy and programming the machines wrong led to this.
bluetwo 10y ago
I agree. They didn't talk at all about any QA processes that should have or would have caught issues, or what they have instituted since.
kurthr 10y ago
It's worth noting that the number of actual failures is measurable only after millions had shipped. 10-100 dppm is a reasonable guess (~100 phones out of 2.7M shipped) with relatively low "infant mortality" until they were compressed into a phone and used (and abused as normal). As a tester, you build a 10k ($10M) unit test run and none of them fail, and then another 10k ($10M) run and again none of them fail... statistically you might not expect reliably catch a single failure until you run 10 times.... that's a $100M test you need to get your boss to sign off on. Note that when you get a failure it will burn up and you won't be able to identify the cause. Now, if you knew the failure mode, you could test for it directly and you wouldn't have to waste an entire assembled phone in a destructive evaluation, but that's hind sight. The failure defects they see seem like pretty standard problems, but other than sampling, I'm still not sure how they are going to catch them in manufacturing. What's amazing is that more batteries don't go up (the original Prius was notorious).
- Dylan16807 10y ago
  Missing insulation especially sounds like a problem that would be in a whole lot of batteries, and should be easy to find in a test run.
  - grandalf 10y ago
    It was only a factor after the case had been partially damaged. Let's hope that the testing procedure will start to inflict similar damage to catch this sort of failure more quickly.
    - Dylan16807 10y ago
      It only causes a fire if there are other factors. But it's very easy to find on an intact battery being examined for flaws.
- taigeair 10y ago
  What's the original Prius issue?
  - dmethvin 10y ago
    Corrosion from leaking electrolyte would eventually short the battery terminals to the protective shield around the battery cells. At that point the battery would catch fire. It just happened to me 3 months ago, 2002 Prius on a battery that was serviced for the recall in 2004. Electrolyte continued to leak, obviously. :/ https://twitter.com/davemethvin/status/782610209525170176 https://twitter.com/davemethvin/status/782610209525170176
sangnoir 10y ago
> My question is why wasn't their QA process catching this in the factory? Especially after the first recall There were 2 battery suppliers, the initial recall was done because batteries from the first supplier (a Samsung subsidiary) had structural/design defects. To make up for this lost capacity, they ramped up production at the second supplier without much of a heads-up. Unfortunately the Quality Control was not adequate for the higher volumes, resulting in well-designed but sloppily made batteries that were also prone to explode. The problem in the second case was not a structural one, but in the manufacturing process.

owenversteeg 10y ago

Samsung SDI is separate enough from the smartphone makers that I'd guess it just wasn't prioritized as much as it should have been. 2.5 million phones were sold, at 14 watt hours per battery that means that the Note 7 batteries would only be a few percent of their total production (35 MWh of Note 7 batteries produced.) Catching problems like this can be pretty tricky and at the end of the day it's also possible that a few people getting lazy and programming the machines wrong led to this.

bluetwo 10y ago

I agree. They didn't talk at all about any QA processes that should have or would have caught issues, or what they have instituted since.

kurthr 10y ago

It's worth noting that the number of actual failures is measurable only after millions had shipped. 10-100 dppm is a reasonable guess (~100 phones out of 2.7M shipped) with relatively low "infant mortality" until they were compressed into a phone and used (and abused as normal). As a tester, you build a 10k ($10M) unit test run and none of them fail, and then another 10k ($10M) run and again none of them fail... statistically you might not expect reliably catch a single failure until you run 10 times.... that's a $100M test you need to get your boss to sign off on. Note that when you get a failure it will burn up and you won't be able to identify the cause. Now, if you knew the failure mode, you could test for it directly and you wouldn't have to waste an entire assembled phone in a destructive evaluation, but that's hind sight. The failure defects they see seem like pretty standard problems, but other than sampling, I'm still not sure how they are going to catch them in manufacturing. What's amazing is that more batteries don't go up (the original Prius was notorious).

Dylan16807 10y ago
Missing insulation especially sounds like a problem that would be in a whole lot of batteries, and should be easy to find in a test run.
- grandalf 10y ago
  It was only a factor after the case had been partially damaged. Let's hope that the testing procedure will start to inflict similar damage to catch this sort of failure more quickly.
  - Dylan16807 10y ago
    It only causes a fire if there are other factors. But it's very easy to find on an intact battery being examined for flaws.
taigeair 10y ago
What's the original Prius issue?
- dmethvin 10y ago
  Corrosion from leaking electrolyte would eventually short the battery terminals to the protective shield around the battery cells. At that point the battery would catch fire. It just happened to me 3 months ago, 2002 Prius on a battery that was serviced for the recall in 2004. Electrolyte continued to leak, obviously. :/ https://twitter.com/davemethvin/status/782610209525170176 https://twitter.com/davemethvin/status/782610209525170176

sangnoir 10y ago

> My question is why wasn't their QA process catching this in the factory? Especially after the first recall There were 2 battery suppliers, the initial recall was done because batteries from the first supplier (a Samsung subsidiary) had structural/design defects. To make up for this lost capacity, they ramped up production at the second supplier without much of a heads-up. Unfortunately the Quality Control was not adequate for the higher volumes, resulting in well-designed but sloppily made batteries that were also prone to explode. The problem in the second case was not a structural one, but in the manufacturing process.