Misaligned Factory Robot May Have Sparked Chevy Bolt Battery Fires (arstechnica.com) 42
An anonymous reader quotes a report from Ars Technica, written by Tim De Chant: GM announced last Friday that it was recalling every Chevrolet Bolt it had ever made, including the new electric utility vehicle model that debuted this year. After a string of fires affected Bolt models, the company traced the problem to two simultaneously occurring defects in the cars' LG Chem-made batteries. The automaker initially discovered the problem in batteries from one of LG's Korean plants, and it recalled cars with those cells last November. But then more Bolts caught fire, and other LG plants were ensnared in the investigation, spurring two expansions of the recall. The problem, GM said, has been traced to a torn anode tab and a folded separator.
That's all GM has said so far. It hasn't said how widespread the defects are, nor has it said how, exactly, the fires started. But in what little information has been released, and in the timing of GM's recalls, there are clues. To decipher them, Ars spoke with Greg Less, technical director of the University of Michigan's Battery Lab. "What we're looking at is a perfect storm," Less said. The Bolt's battery packs are made up of pouch-type cells, which are essentially layers of cathodes, anodes, and separators that are flooded with liquid electrolyte and encased in a flexible polymer pouch. The torn anode tab, he said, would create a projection in what should be an otherwise flat battery. The projection brings the anode closer to the cathode. "And that would probably be OK if the separator was where it was supposed to be," he said.
But in problematic Bolt batteries, the separator wasn't where it was supposed to be. Separators are placed between the anode and cathode to prevent the two electrodes from touching. A torn tab wouldn't necessarily be an issue on its own because the separator would prevent any projection from bridging the anode-cathode gap. In cells with a folded separator, though, the gap would be missing from at least part of the battery. If the anode bridges the gap, Less said, "you have a short, and it's all downhill from there." "It wouldn't surprise me if both defects are caused by the same thing," he added. "I would imagine that the separator must be folded at the edge near where the anode tab is at. What I'm guessing is that at some point during the handling of the cell, before it's fully packaged, some part of the robot machine is catching. The tab is catching, the separator is catching -- something is catching very infrequently so that it hasn't been noticed, and it's causing this damage."
That's all GM has said so far. It hasn't said how widespread the defects are, nor has it said how, exactly, the fires started. But in what little information has been released, and in the timing of GM's recalls, there are clues. To decipher them, Ars spoke with Greg Less, technical director of the University of Michigan's Battery Lab. "What we're looking at is a perfect storm," Less said. The Bolt's battery packs are made up of pouch-type cells, which are essentially layers of cathodes, anodes, and separators that are flooded with liquid electrolyte and encased in a flexible polymer pouch. The torn anode tab, he said, would create a projection in what should be an otherwise flat battery. The projection brings the anode closer to the cathode. "And that would probably be OK if the separator was where it was supposed to be," he said.
But in problematic Bolt batteries, the separator wasn't where it was supposed to be. Separators are placed between the anode and cathode to prevent the two electrodes from touching. A torn tab wouldn't necessarily be an issue on its own because the separator would prevent any projection from bridging the anode-cathode gap. In cells with a folded separator, though, the gap would be missing from at least part of the battery. If the anode bridges the gap, Less said, "you have a short, and it's all downhill from there." "It wouldn't surprise me if both defects are caused by the same thing," he added. "I would imagine that the separator must be folded at the edge near where the anode tab is at. What I'm guessing is that at some point during the handling of the cell, before it's fully packaged, some part of the robot machine is catching. The tab is catching, the separator is catching -- something is catching very infrequently so that it hasn't been noticed, and it's causing this damage."
It's ITS fault. (Score:4, Interesting)
Misaligned Factory Robot May Have Sparked Chevy Bolt Battery Fires
Ah yes, first we blamed the engineers when things go wrong. Now we're starting to blame the robots.
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Sounds like human error to me.
Now we just need to create robots that align the robots. And robots who program the robots which align the robots. And...
Eventually it'll be robots all the way down!
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https://www.midstory.org/wp-co... [midstory.org]
Re:It's ITS fault. (Score:4, Interesting)
Sounds like human error to me.
Dave: How would you account for this discrepancy between you and the twin 9000?
HAL: Well, I don’t think there is any question about it. It can only be attributable to human error. This sort of thing has cropped up before, and it has always been due to human error .
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Who made and programmed the robots?
Oh yeah, humans.
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Not blaming the robot, blaming the persons and systems involved in aligning and checking the alignment.
Although, this does point to fact about modern manufacturing. People can screw up, but a machine can screw up an entire manufacturing run. This points to quality assurance problems, the alignment had no feedback apparently alerting plant managers of the problem.
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This would still be blaming the engineers, just different ones. Engineering for production is an important job because stuff like this can happen if it goes wrong. When you make large numbers of an expensive thing it needs to very good quality control.
They are in a bit of a pickle with this one because they can't easily check these packs for this defect. They probably need to remove them from the car and x-ray them. I imagine the plan will be to replace them with new ones in the short term, and in the longe
Blaming the robot is CYA (Score:4, Interesting)
Every single Bolt is being recalled. Which means they think the issue could be in every single battery made for the Bolt.
If such a high proportion of batteries have issues, then even the simplest of QA tear downs should have caught the problem. That QA didn't detect this is more problematic than a simple mis-aligned robot.
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You know this was probably brought up but the MBA guys decided to ship them anyway.
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You know this was probably brought up but the MBA guys decided to ship them anyway.
So I had an ongoing debate with a manager. There would be a bug deferral procedure before a product shipped. In it any bug could be deferred to the next release, including show stopper bugs. I claimed that a show stopper bug should be degraded to a high or medium priority bug if we shipped with it. After all, we didn't stop the show. His argument was management was making an informed decision on the business impact, not the severity of the bug. Was a fun ongoing argument either way
Re:Blaming the robot is CYA (Score:4, Informative)
Management logic always comes down to this: If we don't ship, we don't eat. So we ship and figure out the rest later. That procedure always works until the time that it doesn't and the defective product sinks the customer or the company. Everything else is just fancy word games.
Re:Blaming the robot is CYA (Score:5, Informative)
Every single Bolt is being recalled. Which means they think the issue could be in every single battery made for the Bolt.
If such a high proportion of batteries have issues, then even the simplest of QA tear downs should have caught the problem. That QA didn't detect this is more problematic than a simple mis-aligned robot.
No. This is happening because the issue is rare not because the issue is common. As the TFA says, if the issue were more common, QA/QC would have caught it. Visual inspection won't show this particular problem. You have to either open (and damage) the battery or you have to x-ray it. Because of this, the QC process was to sample a small percentage of the batteries. They need to recall all of the cars because they cannot easily tell which cars have the problem.
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Yep manufacturing is hard and engineers biggest fears are 1 in a >100 failures or it does it once a week.... so time consuming to debug.
Yesterday we had an emergency 'help' from a company near us who makes industrial led lighting. We were too expensive so they went to china. They have $$$ of boards failing because of overheating and can't work out why... and that's on a really simple product.
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Interesting that they didn't x-ray every pack though. A large industrial x-ray machine would not be cheap but would be worth it. Faults could be detected with machine vision, similar to PCBs.
I'm sure there is a good reason why they didn't, but if I were building that kind of battery pack it's the first thing I would think to do.
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Exactly. In times when every bag of sweets is x-rayed to document that there is no metal in it, this seems like a bit of an oversight.
They could have even stored the pictures, and analysed them later for the problem, identifying the vehicles that have to be recalled. But none of that is possible now.
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There might be a good reason for it. Maybe the assembled pack can't be x-rayed for some reason, too dense or something. I'm sure LG would have thought of it. Machine vision inspection of things like PCBs is routine now.
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It doesn't have to be a high proportion of cells or packs that have the problem. If there's no way to predict which packs don't have the problem, then all must be recalled. It seems like this is an LG problem as much as it is a Chevy problem. Unfortunately, Chevy has not demonstrated that they have any special institutional knowledge about battery packs. They seem to have farmed out both the energy storage and powertrain systems entirely. That kind of work is ok for long-established platforms like gas
The future has (Score:4, Insightful)
More massed produced errors.
Robots speed up and automate human error. Fail fast fail often yay.
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More massed produced errors.
Robots speed up and automate human error. Fail fast fail often yay.
Or, as Mitch Ratcliffe said:
“A computer lets you make more mistakes faster than any other invention with the possible exceptions of handguns and Tequila.”
Vision. (Score:2)
> "the separator must be folded at the edge near where the anode tab is at. [...] at some point during the handling of the cell, before it's fully packaged, some part of the robot machine is catching. "
(Where it "is at"? Sigh).
That sounds very plausible. However, I thought it was a "best practice" for computer vision systems to inspect critical parts/assemblies/steps. Was this not performed? Shouldn't it have been?
Don't miss the real story. (Score:1, Offtopic)
This is proof the Elon Musk is a fraud following a delusional ponzi-scheme business plan who will be arrested by the SEC any minute now.
That said, I have a Model Y that I got a year ago last June and I still run into people now and then that wonder if I am worried about it catching fire. Far fewer than there used to be but it just goes to show how deep the first-impression sensational media narrative runs.
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... I have a Model Y that I got a year ago last June and I still run into people now and then . . .
You need to stop using Autopilot [reuters.com] then
Really just another thing Tesla got right. (Score:3)
Really can't see pouch cells being a good idea for automotive use.
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Tesla batteries have had plenty of problems over the years. Their 85kWh packs are notorious. Those problems include catching fire.
The main issue with cylindrical cells is that they are expensive. That's fine if you are a luxury car maker like Tesla but if EVs are going to be affordable then the battery prices need to come down, and pouch cells are the way to do that. They are also more environmentally friendly, needing fewer raw materials and being easier to recycle.
The industry has mostly settled on pouch
Misguided factory robot (Score:2)
Misguided factory robot tries to burn all humans.
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Misguided factory robot tries to burn all humans.
Yeah. "Misguided".
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"some people call them terrorists... these robots have simply been misguided."
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Maligned Robots (Score:2)
I misread as "maligned factory robot" and figured my worst fears were coming to pass.
Uninformed dude spouts opinion. (Score:3)
This is a guy who knows some practical things about batteries. Granted. But he's basically making up a scenario that equates to "there was a manufacturing defect." He's almost certainly right. But he's also utterly useless, stating the obvious without specifics. His words add nothing to the topic.
This kind of whoring for camera-time is one of the reasons why many people distrust experts.
Opel Ampera e also recalled (Score:2)
It's effectively the same car but sold for the European market, also manufactured in the same facility as the Bolt. Also recalled.
Battery Management System (Score:2)
Why can’t the battery management system detect a shorted cell and sound an alarm? There are only a few thousand cells, it could not be that hard to detect an abnormal voltage on a single cell. Even a few minutes warning could greatly reduce collateral damages.
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Because GM prices parts out to the thousandth of a cent, that's why. A 0.001 cent difference on a part, in a car with thousands of parts, can add up to $1 - $2 per car. Take that times the millions of cars produced, and you've got a million dollar difference in profit.
It is very likely that the features you describe would add a few dollars to the cost of a car, which would probably have required a company vice president's signature... and given corporate politics, a very unlikely scenario. "You want to
Skynet! (Score:2)
Land of the misaligned robots (Score:2)
After reading the headline, I have this picture in my head of a misaligned robot wandering around neighborhoods, looking for cars to torch!
With robots you can introduce defects... (Score:2)
... faster and more consistently.