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You kind of missed my point here.
Sorry. I guess I focused on the original point. Regarding the "related" issue; The fire risk defects won't show up like a "normal" weak cell imbalance issue, which can be detected before it gets too bad. The cars that have caught on fire have not shown sudden loss of capacity before the fire. If there was a connection between a cell imbalance issue and the fires, there would be at least some fires with this "tell".

Furthermore, all cells have imbalances. No two cells are exactly alike. The differences between a fire-prone cell and a normal imbalance would not be detectable with the hardware sensors installed in the Bolt, which are installed across cell groups of three, making it all the more impossible.

From a technical standpoint, the failure mode is completely different. Fire-prone cell failure would be caused by dendrites forming at the tear and bridging the folded separator area. This is a well-known type of failure that occurs suddenly with no warning whatsoever. There's some lab-level test methods for detection on individual cells, which don't work reliably, but that's it.
 

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From a technical standpoint, the failure mode is completely different. Fire-prone cell failure would be caused by dendrites forming at the tear and bridging the folded separator area.
You described the physical defect. What I am still unclear on is what types of warning signs CAN this produce while it is happening? Is a cell in this condition more likely to create a
significant imbalance? I don't know.
I am speculating that GM's next round of software looks for some sort of anomaly that is produced by the specific scenario you laid out. Based on GM's use of the term "might" when discussing whether the software will identify bad cells, I assume whatever it is won;t occur in every cell that has the defects, but is present enough of the the time to be worth watching for.
 

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What I am still unclear on is what types of warning signs CAN this produce while it is happening?
None. Imagine connecting a pair of jumper cables to the 12v battery. Now slowly bring the two clamps closer and closer until KABOOM! You had no way of detecting that giant spark the instant before it happened. That's how dendrite failure works. The dendrite grows closer and closer until suddenly, KABOOM!

Now, there is a possibility of tiny dendrites going poof, without starting a fire, as a precursor to the big one. But that's back to lab-level detection methods and there's no way of knowing if a cell will have minor ones or go straight to the big one.
 

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Just because the solution won't help YOUR inconvenience doesn't mean that they aren't trying. And this is designed simply as a stopgap until batteries get replaced. I'm sorry to hear that it isn't going to help you.
I was only speaking for myself and why I said we might be looking at the same thing differently... indeed we are. I will admit I find it hard to think reducing to 80% is helping anyone, but if that allows them to get back up above 90% and that was a hindrance, then yes it's helping. My hypothesis is those of us that are inconvenienced are more so hindered by the 70 miles of range and not the 10% of charge at the top though... so helping, perhaps, meaningful, not really.

On a different note, how long is your commute?
My commute changes daily right now due to a large interstate construction project. Someday I can go full highway, other days my exit is closed and I take back roads in (dropping from a 70 MPH limit to 55 MPH) and some days I head to the exit after mine and backtrack. More to the point...

170-180 miles is "fully" charged at 90% currently. I tend to arrive home somewhere around 110-120 miles of range. My return trip (in the morning, when temps have dropped) puts me 70 or less miles of range. If I wanted to run an errand, or head out for dinner with my wife, or anything else other than commute to/from work then I'm adding 20 miles consumption. I have to pick and choose how and when I use my Bolt. I'm not actually upset about the defect (me and the wife are not thrilled about the perceived risk), nor am I upset about remedy. I'm concerned about making it to/from work when I can't get a rental car and nobody can tell me when my car will get repaired. I'm not asking or expecting to be moved up the priority list, but I don't think it's crazy of me to expect the rental when gm says they are doing this for customers.
 

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I was only speaking for myself and why I said we might be looking at the same thing differently... indeed we are. I will admit I find it hard to think reducing to 80% is helping anyone, but if that allows them to get back up above 90% and that was a hindrance, then yes it's helping. My hypothesis is those of us that are inconvenienced are more so hindered by the 70 miles of range and not the 10% of charge at the top though... so helping, perhaps, meaningful, not really.
That's my case, significant impact on road trips where you would have done 20-80 and now have to do 30-90 and if that 80 means 30-80, then looks like one would need to drive on the truck lane at 55-60mph while getting passed by trucks driving 70mph.
 

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None. Imagine connecting a pair of jumper cables to the 12v battery. Now slowly bring the two clamps closer and closer until KABOOM! You had no way of detecting that giant spark the instant before it happened. That's how dendrite failure works. The dendrite grows closer and closer until suddenly, KABOOM!
So are you implying that a cell with a folded separator and a torn anode is NOT more likely to get out significantly out of balance (regardless of dendrite growth)? Are there ANY other differences that these physical defects can cause that might serve as an alarm? If GM is saying they have software that will HELP detect problems, I am inclined to believe there is something. We just don't know what it is.
I was only speaking for myself and why I said we might be looking at the same thing differently... indeed we are. I will admit I find it hard to think reducing to 80% is helping anyone, but if that allows them to get back up above 90% and that was a hindrance, then yes it's helping. My hypothesis is those of us that are inconvenienced are more so hindered by the 70 miles of range and not the 10% of charge at the top though... so helping, perhaps, meaningful, not really.
Who said the software will limit the top charge at 80% AND keep the low-end restrictions in place? That part is still very much unknown. If the software leaves a customer with a total of 80% range, then that is an improvement over current guidance right away. I suppose we merely have a difference of opinion on this. We also have a lot of speculation, as we lack details on what this software update will ACTUALLY accomplish.
 

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Are there ANY other differences that these physical defects can cause that might serve as an alarm?
Doubtful. If it was possible to open up a battery pack at a specialized facility and test for the defects, replacing only the cells or module sections that are defective, that could save GM and/or LG about a billion dollars in replacement cells. The fact that they have no plans to do this and will replace the entire battery should be clear indication that it's not possible under any conditions.

So it goes back to what is currently available in the pack to sense differences. Yes, there could be minute differences in charge/discharge behavior. VERY slight differences that would require calibrated laboratory equipment to detect on individual cells. It's not possible with specialized equipment so it's clearly not possible with the relatively low resolution sensors attached to groups of 3 cells in the Bolt.

P.S. There may be certain areas of the individual cell that would heat differently under charge/discharge, but you're certainly not going to detect that with the 6 temperature sensors scattered throughout the pack.
 

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Doubtful. If it was possible to open up a battery pack at a specialized facility and test for the defects, replacing only the cells or module sections that are defective, that could save GM and/or LG about a billion dollars in replacement cells. The fact that they have no plans to do this and will replace the entire battery should be clear indication that it's not possible under any conditions.

So it goes back to what is currently available in the pack to sense differences. Yes, there could be minute differences in charge/discharge behavior. VERY slight differences that would require calibrated laboratory equipment to detect on individual cells. It's not possible with specialized equipment so it's clearly not possible with the relatively low resolution sensors attached to groups of 3 cells in the Bolt.

P.S. There may be certain areas of the individual cell that would heat differently under charge/discharge, but you're certainly not going to detect that with the 6 temperature sensors scattered throughout the pack.
Then what do you think GM's newest round of software is going to look for? If there is nothing, then why roll out software that is going to cost the company MORE money. Either there is SOMETHING that they can see, or the entire notion of the next software update is a complete and total waste.
 

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Then what do you think GM's newest round of software is going to look for? If there is nothing, then why roll out software that is going to cost the company MORE money. Either there is SOMETHING that they can see, or the entire notion of the next software update is a complete and total waste.
They may be looking for charging patterns that may produce elevated risk, to prioritize for new battery. Or it could, like the last 2 updates, be a complete and total waste.
 

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They may be looking for charging patterns that may produce elevated risk, to prioritize for new battery. Or it could, like the last 2 updates, be a complete and total waste.
OnStar can already isolate the charging patterns and GM has indicated that this is currently being used to help prioritize vehicle order, so that seems unlikely to me.

And there has truly only been one software update that was billed as any sort of "fix". And that did identify several batteries that had significant cell imbalances, resulting in modules (and possibly batteries?) being replaced. So while it most certainly wasn't an actual "fix", I argue that it was not a "total waste".
 

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They may be looking for charging patterns that may produce elevated risk, to prioritize for new battery. Or it could, like the last 2 updates, be a complete and total waste.
Or maybe it's just a random number generator everytime you switch on your car. LOL
 

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The cars that have caught on fire have not shown sudden loss of capacity before the fire. If there was a connection between a cell imbalance issue and the fires, there would be at least some fires with this "tell".
One of the early fires did occur in a car where range loss was seen for some time before it caught fire. Because the evidence is burned up, it is likely impossible to tell whether that was related or coincidental in that specific case.
 

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Well, summer is over and winter is coming fast with the associated battery warming need - esp if parking outside the garage... If you can't charge overnight, does that mean we will be lining up at the DCFC daily? What a nightmare!
Today in Seattle, we got our first near-freezing temps (36F where I was). It was also the first time I saw battery conditioning take up 5% of my 30 kWH of energy used. I'm going to wait-see what the software updates do for others first before bringing mine in for the update. I don't want to lose range due to safety cutoffs in the winter. I average 170mi in the winter with a 100mi commute (+/- 50 mi depending on job sites, traffic, and errands).
 

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I knew I would find joining this forum to be beneficial. The percentage of automotive and electronics engineers here are almost as high as the percentage of medical professionals on Facebook. This is truly a brain trust the likes of which automobile manufacturers can only dream.

The level of absolute certainty some are demanding here is, frankly, laughable. While we all try to mitigate risk and I'm confident none of us here are keen on having a car experience a runaway thermal event while in our possession, I'm relatively certain that, for many, the likelihood of your domicile catching fire due to lint in your dryer vent or the fact that you've not emptied the crumb tray in your toaster is significantly higher than from charging your Bolt.

Can we all keep some perspective here, please? The circumstances are most regrettable and I'm sure both companies are doing their best to bring our vehicles back into the realm of an acceptable level of safety in as short a time as feasibly possible.

It reminds me of when I would get calls from customers (who were in possession of loaner cars from the service department) complaining about why their vehicles were taking so long to be repaired. I assure you, nobody is more interested in getting you back in your vehicle than I am...
 

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I knew I would find joining this forum to be beneficial. The percentage of automotive and electronics engineers here are almost as high as the percentage of medical professionals on Facebook. This is truly a brain trust the likes of which automobile manufacturers can only dream.

The level of absolute certainty some are demanding here is, frankly, laughable. While we all try to mitigate risk and I'm confident none of us here are keen on having a car experience a runaway thermal event while in our possession, I'm relatively certain that, for many, the likelihood of your domicile catching fire due to lint in your dryer vent or the fact that you've not emptied the crumb tray in your toaster is significantly higher than from charging your Bolt.

Can we all keep some perspective here, please? The circumstances are most regrettable and I'm sure both companies are doing their best to bring our vehicles back into the realm of an acceptable level of safety in as short a time as feasibly possible.

It reminds me of when I would get calls from customers (who were in possession of loaner cars from the service department) complaining about why their vehicles were taking so long to be repaired. I assure you, nobody is more interested in getting you back in your vehicle than I am...
It's a real thing!
 

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...

Who said the software will limit the top charge at 80% AND keep the low-end restrictions in place? That part is still very much unknown.
^This is part of my issue. Because gm can't and hasn't said what the impact will be I need to take action about a rental car now. Why now... because gm is slow to make anything happen. If I wait until the software is available in Nov. and my range is limited further, I won't be able to go to work. I bought a car to drive, not to be limited in my driving. If their defects and temporary fixes can't do what the vehicle is intended to do (which it hasn't now for almost a year) they need to make some alternative available.
 

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^This is part of my issue. Because gm can't and hasn't said what the impact will be I need to take action about a rental car now. Why now... because gm is slow to make anything happen. If I wait until the software is available in Nov. and my range is limited further, I won't be able to go to work. I bought a car to drive, not to be limited in my driving. If their defects and temporary fixes can't do what the vehicle is intended to do (which it hasn't now for almost a year) they need to make some alternative available.
Or you could just pass on the software update until your battery is ready. Don't overthink this one. Either it will help you or it won't change anything. It cannot hurt you any further than GM's current guidance.
 

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EV techs have to go through a ton of training before they can work on these batteries. Many dealers have received visits from their GM reps recently to go over everything about this recall. So, right now, these techs that you think so lowly of are probably the best source of INFO we can ask for.
I didn't say I thought "lowly of them". All I meant was they are very likely only told exactly what they need to know.to do a particular repair, and nothing more. And you can tell from what the Tech posted that he really doesn't know anything more than what owners are going to be told very shortly. There were no revelations in there. But there was some personal speculation, which he really shouldn't have done because that can cause confusion.
 

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But there was some personal speculation, which he really shouldn't have done because that can cause confusion.
Yes, no one should speculate on the internet!!! ;-)

To be fair, he mentioned that it was his personal thoughts...
First let me say that I am not an official GM spokesperson and I am expressing my interpretations of the information I have gathered.
 
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