My Chevy Bolt Is On Third Battery Pack: Here’s Why


General Motors says that I’m special.

Nearly 43,000 Chevy Bolt electric cars have been sold in the United States. According to General Motors, only one of those Bolts needed its battery pack replaced not once, but two times. And who is the winner of that unfortunate lottery? Me.

“You’re the one in a million second-event person,” Tim Grewe, chief engineer of electric propulsion systems at General Motors, told me in a phone call last week. “This is a terrible thing that happened to you. And even though it’s so rare, we never want it to happen again.”

The saga is long and detailed. So I’ve encapsulated it in a timeline. Below that, you’ll find an excerpted interview with Grewe.

The Story Begins

  • Mar. 6, 2017: My 2017 Chevy Bolt Premier rolls off the assembly line.
  • June 16, 2017: I receive the car in a three-year lease.
  • Aug. 8, 2017: The Bolt abruptly stops, leaving me dangerously stranded on the side of the road.
  • Aug. 22, 2017: GM diagnoses a low-voltage problem in Cell 25. The entire battery pack is replaced. My Bolt shows 1,746 miles on the odometer.
  • Aug. 24, 2017: I post an account of what happened on I report that GM notified about 100 Bolt owners that they could face a similar issue.
  • Sept. 11, 2017: GM Communications informs me in an email that the company made “improvements throughout the supply chain” to correct the cell low-voltage problem.
  • Sept. 18, 2017: I learn of additional Bolt drivers (including a pregnant woman on a busy Los Angeles highway) who were stranded on the roadside but had not been notified by the company. GM says that OnStar data needs to be collected for some time to identify at-risk vehicles. Therefore, new Bolt owners (or cars on dealerships lots) could encounter the same problem.
  • Sept. 2017 – Mar. 2018: Bolts with new battery packs appear to be reliable. GM works with LG Chem, the battery supplier, to make multiple changes to the cell manufacturing process. The company believes the problem is fixed.

Software Fixes for Earlier Warning

  • April 2, 2018: Chevrolet issues a recall for drivers of 2017 Bolts to get a software update to provide more warning about any potential “cell low-voltage condition” and loss of propulsion. The software change allows cars to continue driving with a diminished range rather than forcing drivers to make an immediate stop.
  • May 11, 2018: GM releases a new software update for all Bolt owners (not just for 2017 models) to “provide additional warnings.” GM later tells me the software “increases the accuracy of the range estimation in addition to providing more warning at low states of charge.”
  • May 14, 2018: My Bolt receives the April and May software updates. GM tells me that the company is continuing to monitor all Bolts so it can “proactively contact owners to have their batteries serviced as soon as our diagnostics confirm batteries are suspect.”

Deja Vu All Over Again

  • Oct. 2018: I begin to notice diminished range. I use a dongle-based tool provided by FleetCarma to pull more precise data from my Bolt’s diagnostics port.
  • Nov. 20, 2018: In a post on, I report detailed range numbers about a 184-mile late trip that reveals my Bolt’s battery capacity is reduced from 60 kilowatt-hours to about 35 kWh.
  • Nov. 21, 2018: I alert GM about the problem. Chevy Communications responds: “The team is looking into what could be the cause using remote diagnostics.” I am later told that the problems with my Bolt are communicated “all the way to the top” of the company.
  • Dec. 3, 2018: I receive a standardized OnStar diagnostics alert stating, “An element in the battery has slipped below the threshold required for good performance. If unrepaired, it could cause a stalling situation while driving.”
  • Dec. 2018 – Jan. 2019: I unsuccessfully try to wrangle Chevrolet and a local dealership to pick up the car for service. Chevrolet Communications tells me that my car is safe to drive – although with diminished range.

My Bolt was back in the shop in January — to get its third battery pack.

  • Dec. 2018 – Jan. 2019: I continue to pull data from my Bolt’s computer system, revealing that the threshold of low to high voltage is beyond the accepted threshold. (See screenshots below.)
  • Jan. 16, 2019: I drive my car 25 miles to the closest Chevy dealership. Diagnostics show the offending low-voltage cell is No. 68. My Bolt receives its third battery pack. The car shows 11,940 on the odometer. I continue to pull data from the computer, which indicates a healthy battery pack and my range is restored to the expected level.

Trying to Understand

  • Jan. 2019: After diagnosing my car’s second bad cell, General Motors – working with LG Chem –  makes additional changes to the cell manufacturing process.
  • Jan. 16, 2019: Six hours after I dropped off my car, Automotive News, reporting from its World Congress event, tweets this quote from GM CEO Mary Barra: “We’ve sold over 200,000 electric vehicles and we have yet to replace a battery pack.” Multiple owners on social media say that they’ve had packs replaced, some as recently as January 2019.
  • Jan. 18, 2019: Chevrolet Communications tells me that, “Mary’s original statement was in reference to the wear out of a battery due to regular use. Upon further review, an estimated less than 0.01% of customer battery packs or sections have been replaced due to suspected wear out.”
  • Feb. 1, 2019: I speak with Tim Grewe, chief engineer of electric propulsion systems at General Motors.

The Interview

On Feb. 1, I spoke with GM’s Tim Grewe for nearly 40 minutes. Here’s how the conversation went – edited for clarity and brevity.

InsideEVs: Was the issue of the delta between low and high voltage of cells the same problem during both the 2017 and the 2018 incidents with my car?

Tim Grewe: It resulted in the same customer experience of reduced range and early capacity fade. When you do a 100-percent charge, and you have one cell not at the 4.1 level, like a cell at a lower 3.8 voltage, then that cell is not matched to the other cells in the pack. It was not the same quality issue as before although they were related.

On my second pack, Cell 68 had low voltage, thus creating an imbalance and low range.

Help me understand the difference between the two.

We have 280 cells in a Bolt. It has to do with the geometry of the cell. Even at a smaller level than the cell, there’s a lot going on. You have to make sure everything ages appropriately. Batteries expand, contract, and vary with temperature. It’s electrochemistry. And so there were two problems that took a while to manifest themselves. There were some very subtle things that happened in the supply chain and in the cell assembly that caused the inside of those cells to fade.

Do you test every single cell before it goes into a pack?

We do extensive tests. When you make a cell, it’s not energized. You have to put it through a formation stage. The anode and cathode formation phases take a long time. Then we have a quality system where we monitor them. They’re stored to make sure there are no subtle changes happening. We also have quality-control systems that monitor the pre-compression and post-compression phenomenon.

What do you mean by compression?

We literally press them together. We put highly engineered foam between them. Then we put them all together in the cell-module assembly. Each cell has a validated pressure throughout its lifecycle for hot and cold. Even with all the monitoring we did along the way, these got through all that because the phenomenon took longer to present itself.

When you say phenomenon, you mean something in the chemistry created a diminished capacity to hold the voltage?

Yes. So instead of having a 238-mile pack, you had a 155-mile pack.

That’s what happened the second time. The first time when the system detected the problem, the software said pull over and just stopped me. But the second time it just changed the range number on the indicator?

Exactly. With the prognostics using OnStar, there’s a lot of range of variability in people’s use of the car. So literally your article on InsideEVs was written right at the time when they would have been calling you to say this looks suspicious and bring it into the dealer.

Data after a charging event provides a clearer picture of low voltage.

Are you confident that someone else a month from now is not going to encounter a problem and say, hey, why didn’t you notify me?

Highly confident. I’m not just saying that. You are the only one I know of in the second round.

There were a series of recalls and service bulletins. Did I miss any of them?

No. We want to be confident, but we also want to be humble because this is pioneering stuff. We’re watching with OnStar to protect your experience. We were the first ones out there with these high-range electric cars. We’re doing extra prognostic work to try to make sure things happen the way we expect.

We were so upset with your first experience that we got a fix out there right away, as fast as we could, to make sure the fewest number of customers would have your first experience because that was terrible. Between August 2017 and May 2018, we were trying to hit the problem as hard as we could to prevent the [cars] shifting to neutral and coasting down a hill.

Are you saying that it was partly my case from 2017 that led to new software development and the recall for all Bolt drivers?


Can you go into more detail about the differences between what happened in the first case and second case?

When you make a battery cell, there are a hundred steps. You take the aluminum. You take the copper. You laminate on a cathode material the nickel, the manganese, and the cobalt – and then you put the graphite on the anode. Then you have something called a separator that keeps those two from touching each other. And then you have to put a lot of those in parallel in each side of each and every cell.

There were different subtle manufacturing variance issues between the August 2017 and the January 2019 pack that caused it to lose capacity before the life of the car. It would be misrepresenting it to say it was one thing or another. It was subtle.  Both resulted in capacity losses but for very different reasons. It’s a long tech paper to go beyond that.

Can you locate where the problem was?

We know exactly what happened. Tool usage, maintenance schedules, and that kind of subtle stuff. It was LG Chem’s best practice. It was our best experience with previous batteries. We needed to do some things differently. Not necessarily better, just differently.

The way it’s packaged?

The way it’s manufactured. A battery cell assembly lab is sort of like a newspaper printing press. You start with these huge rolls of paper. And in this case, it’s copper, and then it runs through this coating machine, and then you press it down. Then you heat it and cut it up. And then you fold it into a newspaper, and there are very subtle things in some of those process steps that degraded the capacity in different ways between the two different cells failures.

Have you made any changes in that process?

100 percent. Not only did we fix the issue, but we put extra monitoring to make sure it never happens again. In each case, we work directly with our supply chain. You fix it there and add a monitor in there. Where could a similar thing happen somewhere else in those hundred steps? And how do you make that additional monitoring and those steps as well?

It had to do with maintenance schedules and monitoring. We didn’t just attack just one operation that was the root cause of your cell problem. We read it across to all other similar operations, and we improved it and increased the monitoring of those as well.

Did these corrections happen only on the 2017 issue or the more recent case as well?

We made multiples improvements in 2017 and 2018. But it wasn’t enough. Now the data shows the cells in your 2019 pack are super tight. That’ll be the proof that we finally nailed this thing. But we’re going to continue to monitor with OnStar to make sure that’s true.

The problem in 2017 was experienced by about 100 people. Could one or more of those 100 people also suffer a second fault like what I experienced?

We haven’t found one yet. You’re special.

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265 Comments on "My Chevy Bolt Is On Third Battery Pack: Here’s Why"

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That was thorough. I expect all EVs have this prognostic capability, right?

All Western modern EVs. I expect some models in China do not, and the rudimentary lead acid based EVs of the 1970’s and ’80’s would not either. That said, this is a problem largely specific to the EVs using the far larger prismatic cells shaped like pouches instead of the cylinder cells Tesla uses. A Tesla will have five to seven thousand individual cells, and if one is defective your car should still be able to provide the expected range, and will not need to shut down or limit performance. Tesla still works very hard to ensure all the cells are good. When there are only 280 cells if one goes bad it is a much larger problem, and it seems with the LG Chem pack design they are unable to isolate if from the rest of the battery module it is in, meaning you lose the module.

Most companies other than Tesla are going with prismatic pouch cells, so expect more of these problems with new EV models on the way. Tesla early on did have some faulty battery packs, there is a learning process.

Actually, lead-acid EVs had the same issue– if you have a single string with a single cell running high impedance you will lose range. The old solution was to replace them regularly, but that isn’t economical for a mass-market solution.

@Carmi Turchick, Lead Acid batteries have their own set of problems. Some can be much worse that this story.

My Dad had a 12v blow the hood of his truck open when he tried to start it one day at work… Hydrogen build up.

We cleaned it up with a hose and and baking soda.

“This is a terrible thing that happened to you. And even though it’s so rare, we never want it to happen again.”
At least they have the right attitude about it. I immediately thought of Barra and her “never replaced a battery” remark. All manufacturers will make a lemon here and there, you should try to ditch it.

Bingo ‼️

Somebody tweet Mary Barra and bring her back to reality.

Fortunately the Bolt is on lease, per the article, I believe? So GM is going to get this ill fated Bolt back.

I’m glad things worked out, but I have to wonder how things would have turned out if the vehicle wasn’t owned by someone who isn’t a very active member of the EV community with various articles and publications under their belt.

However I’m probably just being cynical.

Nope. Bank owns or whoever financed the lease

GM ends up with the car in the end in most cases and some poor soul will end up with the car once they sell it again.

No, GM Corp does not, the lender will run this car through an auction and it goes to the highest bidding dealer who’ll put it on his lot…

Crappy way to do it IMO.

Still is a huge problem for the next customer.

Good to know GM/GMAC like to wash their hands of their cars.

Even Nissan resells grounded leased Leaf’s through their dealer network.

Nissan and every other manufacturer offers their lease vehicles back to the dealers in a set process. I’m familiar with one where the receiving dealer has 2 or 3 days to buy the lease return, after that it’s made available to other brand dealers for a week or two, and then it’s offered at open auction. I’d guess that factory leases from GM are handled in much the same way.

Why do you automatically assume the car will be a problem for the next customer since the offending battery has been replaced?


yes, depending on the car maker, lease returns usually go through something like this:

1) Dealership processing the lease return usually gets the chance to take ownership of the car at a fixed price.
2) If the dealer doesn’t choose to take the car, it usually goes onto an online dealer-only site where branded dealerships can buy them.
3) If no other branded dealerships grab them, they go to Mannheim private auctions.

Not sure why you got down voted, you’re entirely right. We need to publicize the VIN number of this vehicle when he trades it in, so when the next customer has the inevitable issues, maybe they can find their VIN number all over, associated to this issue. It would save them thousands.

The VIN number does not identify the battery pack, does it?

If anything, this VIN will have the best and newest battery out of all 2017 Bolts out there, making it the “best” 2017 of the bunch.

GM DOES have the two failed packs though…

It’s all about how she worded it. Technically they haven’t replaced a battery based on degradation. These issue are cell defects.

Sure. The battery degrades to a certain percentage then crashes completely…is that degradation or defect? i guess that’s the beauty of it, you can choose the one you like best. And no, it’s not a GM issue….Tesla had similar incidents.

I have a friend with a Tesla with like 90,000 miles. He got a call from Tesla that something was going on with his pack so they gat him a new one.

My point exactly. Battery issues will happen on a few cars if you sell enough of them.

The nuance here is that one single cell rapidly degrades in the case of a Bolt pack. versus Nissan’s issues with many, many packs where the whole thing just wears out too soon. The Bolt issue is about 100 bad cells in otherwise good packs, Nissan’s issue was that every cell in every battery they made wasn’t up to the task of withstanding use and heat.

Yeah…Tesla uses cyclindrical battery cells, LG Chem uses prismatic pouch cells for the packs it makes for the Bolt. There are five to seven thousand cells in a Tesla, 280 in a Bolt. Usually if one cell goes bad in a Tesla the car still works just the same. So Tesla did not have similar incidents. It has had to replace some packs, the vast majority of them in the first year of Model S production. Things can go wrong, but you are highly unlikely to be stranded by a Tesla with a faulty battery pack.

Beyond the cell count, Tesla also does a parallel-series combination, so there is never a single cell in series with other cells.

That’s right. This problem was the result of a manufacturing defect, which is much different from degradation that occurs from normal operation of the vehicle. The Volt and Bolt have been nearly immune to the latter. About 100 Bolt customers have suffered from the former, and this poor guy suffered from it twice.

Re: Mary…

A total trump move.

It’s all in the chosen words.

In the end it’s too confusing for most to question.


Or a total Musk move. Didn’t Elon write the following tweet today?

“Model 3 starting cost now ~$35k. . .
— Elon Musk (@elonmusk)
February 6, 2019”

It’s all in the chosen words.🤦🏻‍♂️

At least make the effort to post the entire tweet, troll!!

Exactly ‼️

It’s not what you say but how you say it. said:
“I immediately thought of Barra and her ‘never replaced a battery’ remark.”

At least make the effort to post the entire remark, troll!!

You’re the troll, dude. That was the entire remark. Perhaps she meant it to be taken only in the context of battery aging (rather than malfunction), but what she is quoted to have said is exactly what’s quoted above.

OK kids. So my question, does anybody have the entire context of the Mary Bara quote? Or all we all just trolling?

Oh bother:

Automotive News
✔ @Automotive_News

Barra: We’ve sold over 200,000 electric vehicles — and we have yet to replace a battery pack. #ANWorldCongress

7:40 PM – Jan 16, 2019
She lied. Is that clear enough for you.

You don’t know what context means do you?

Context is irrelevant. She made an all inclusive statement.

Agree here with you Null. Barra, like almost all GM Execs – talks blather all day and you get little information…

Don’t know why cell equalization wasn’t mentioned as a method.

My Bolt was actually down to about 52 kwh until after I let the car fully charge and equalize – after the first cycle I was back up to 57.1 and after the second 57.5 kwh . The car has 39,000 miles on it and the ’60kwh’s ‘ battery’s long term rating (after the initial use) is 57 kwh – as this is the capacity listed on the paper label on the battery.

Since I’m still a bit more than its ‘long term rating’ I’m satisfied.

Of course the cell equalization can only happens in groups of 3 – there is no access within the group of 3 so that limits a perfect equalization – but it – as my experience has shown – IS NECESSARY from time to time and DOES apparently basically help things.

Hmmm, why did have him drive the defective car for so long. Tesla would have simply picked up his car, replaced the battery and have him back driving in a couple of hours. Tesla would then have run their own diagnostics.
Fail on GM once again.

Lee…you are in charge of determining when Tesla replaces a battery pack? Sounds like it. LOL

Have you been following Bjorn Nyland problems trying to get his Model X repaired? Tesla made him wait something like 39 days, with poor communication during that time! No car company is perfect, but I does seem like GM handled this relatively well.

He used it for truck pulls.

That blows the warranty out the door.

You replaced half his tweet with “. . .”

Not really a Trump move. Trump doesn’t bother picking weasel words, he just brazenly outright lies.

Trump is no more liar than Obummer “deporter in chief” who canceled fusion research while claiming “I care about climate change”.

If you really want to see the liars, take a look at Dumbocrat politicians who claim “I care about climate” yet driving around in giant gassers. Those are the real liars too stupid to know that evidence to the lie is plainly obvious.

This is really confusing except as a parody. Yes, Obama really did care about climate change and took several effective actions to reduce carbon emissions. Fusion research continued under the Obama administration. Whether or not fusion research was cancelled doesn’t mean someone lied about caring about climate change. Fusion power has thus far not reached ignition and cannot be counted on as a viable energy source.

Trump doesn’t believe in addressing climate change and habitually undermines the science behinds it. Trump cancelled several NASA programs to study the climate as well as the Clean Power Plan and acted to block higher CAFE standards. He also still has a special tariff on solar panels above and beyond other Chinese tariffs in addition to uncountably many other initiatives to undermine climate-mitigating policies started during the Obama administration.

More than anything, deflecting to Obama or Democrats doesn’t make Trump less of a liar. It is extremely childish to use name-calling, deflection, and extremely poor logic to cover up for the failings of someone in your tribe. Now I understand that you may in fact be a child, but even so, you should avoid this type of behavior.

In your view, someone who cancels a technology that will hugely benefit curbing CO2, yet claims he cares is not a liar. But someone who says he doesn’t believe is a liar? This is the fundamental problem of echo chamber brainwashing. You can’t tell a lie from truth.

As for “climate change is going to kill us all” religion that you believe, humans are doing better than ever despite climate change. There is literally zero evidence that climate change harming humanity as a whole other than propaganda films.

But facts be damned, you will continue to push to support Dumbocrat politicians who drive giant gassers if they say they will forcefully take other people’s money (including yours) in name of climate change religion.

I was very careful to only state facts in my response to you. What I said is true independently of which political party you or I support. That isn’t easy. My browser tabs are usually filled with primary sources for every claim that I make even in a casual article comment section such as this one. If there is even a single sentence in my response that you can directly factually refute, you are welcome to do so.

However, your response to me is conversely filled with a completely unhinged and hyperbolic abandonment of reason and factual arguments. But since the crux of your claim is that Obama cancelled fusion research, can you start by stating exactly which fusion project Obama cancelled?

When your response to a claim that someone is a liar is that other people have lied too, you’ve already lost the argument.

He’s closing in on 9,000 lies since inauguration alone.


If you think Trump is lying all the time, you’re brainwashed. “Poll Shows Americans KNOW Media Is Lying About Trump” by very respectable and probably most trustworthy journalist out there.

It is extremely dangerous to believe someone unconditionally and it is important to maintain the ability to evaluate the truth of a statement independently without being coached in what to think. It is true that almost everyone lies. It is true that Trump pathologically lies. Those are conclusions that you can come to independently of any external narrative and it is not the media’s fault that people have come to that conclusion. It would take much more conditioning and brainwashing to come to the conclusion that Trump doesn’t lie at least more than normal.

You can keep your DOCTOR! From the biggest lier of all time!

Even if Obama planned for everyone to lose their doctor and then went on stage and declared that they wouldn’t, you can’t use the same line to nullify every single lie ever made from that point onward. At the very most, that would nullify a single health care promise from the Trump administration.

In reality one lie doesn’t negate another, so seriously, grow up and demand better from politicians.

You right wingers can only point to ONE time Obama was partially incorrect. OTOH, Trump lies 12 times a DAY. You are seriously twisted to actually compare these two presidents on truthfulness.

This is why Trump has the support of 35% of the electorate no matter WHAT Trump does. You folks have inhaled the Trump-ade to the point where he can do no wrong.

Trump is no more a liar than most other politicians, and less of a liar than Obummer. In fact, the biggest liars are socialists in Dumbocrat party who promise paradise by promoting policies of North Korea and Venezuela. How many of them drive giant gasser while spewing lies about climate change?

Make no mistake, they do not support Nordic model that promote business (ie, zero minimum wage, lower business tax than US), instead they only talk about policies of Venezuela that doomed one of richest countries in South America.

But again, I doubt you’ll see the lies when you’re so entrenched in propaganda.

Again, there is nothing in my response to you that was not objective and if you disagree, I hope that you would at least try to falsify an actual statement that I said. What you did was go on a hyperbolic rant, which again included name-calling, deflection, and poor logic and did not in any instance prove or show that Trump does not lie more than normal. I understand that this is a defense mechanism, but I’m not easily distracted by tangents on North Korea and Venezuela.

And also again, the conclusions I have come to are not a product of propaganda. I still possess the ability to think independently and clearly about topics as well as re-evaluate any conclusions I have made in light of new evidence.

You really can’t draft a coherent argument without blowing insults out your hole, can you? Once someone of any reasonableness reads your little “Dumbocrat” insults and your so original “Obummer” screeds, they all know where you come from.

t-Rump is our POTUS, and a very effective LSOS.

I’m still wondering when his pants will ignite!

It’s clearly Trumpian, call it a battery pack, or part of the propulsion system, or cells, or whatever, but there has never been a problem, difficulty, or poor engineering.
The person wants their battery to fail, and they absolutely love it when it does, and they can’t pick up their paycheck.

Yeah…and what is the most miles on any Bolt? They would be torture on a road trip with their slow recharges, so I assume 30,000 miles would be the most someone could have driven one of these cars already. No batteries back because of degradation should be a given as the vast majority of the packs have fewer than 100 charge cycles so far.

More concerning:

“Jan. 2019: After diagnosing my car’s second bad cell, General Motors – working with LG Chem – makes additional changes to the cell manufacturing process.”


Or so they say.

It’s like Nissan bringing my Leaf in to perform a update that does absolutely nothing.

Only in Europe does the software update preform, “absolutely nothing” is for the US Leaf MAGA crowd.

#rapidgate is supposedly fixed, with the latest patch for 2018-19 40 kWh EuroLeaves.

Nissan has done very little.

That’s another reason why no longer buy Nissan.

The other is the scandalous way they operate, combined with Japan’s hostage justice.

I am not deeply informed on the case, BUT Nissan is not to be confused with those keeping the man in jail. Wealthy individuals tend to go missing to the Carribean. Yes there is history to that. So for a story with much to be established the jailhouse has a purpose.

Well then do some reading on some of the details and you will see nothing but corruption on the parts of everybody involved including Nissan’s current Sleazebag CEO, to whistle blower, Hari Nada that turned on his good friend Greg Kelly who is also stuck in Japan after his arrest on November 19th as well.

Nissan & smaller partner Mitsubishi are both super corrupt, as is Japan Inc. when the business deal doesn’t go their way regardless of how small their interests are.

Crazy wild ride of a story that would no doubt make one hell of a movie.

LG Chem makes the battery cells, battery packs, motors, inverters, basically everything electrical in the Bolt. Probably GM had little to do with any changes made, and may not even know all of the changes made. LG Chem is going to be making battery packs for lots of automakers with, one assumes, the same cells and similar design, so they need to get it right.

Your response is completely illogical. Given that the problem was the battery, and he has the most closely watched battery in the entire Bolt fleet, why would he want to lose this car now?

“All manufacturers will make a lemon here and there, you should try to ditch it.”

The lemon in this case was the battery pack and it’s been completely replaced. Ditching the rest of the car that apparently has been just fine would be pointless.

With nearly 12K free battery miles and a new pack, you should buy the car at lease end.

“Between August 2017 and May 2018, we were trying to hit the problem as hard as we could to prevent the [cars] shifting to neutral and coasting down a hill.”
What?! That’s news to me! Where do i read about this?

Google it.

Thanks for the help.

Bush League. GM is not ready to play in the EV big leagues.

How many packs have been replaced in Tesla Model S?

Should we ask Barra? She has all the numbers….

“How many packs have been replaced in Tesla Model S?“ Now, that is a dumb comment. I wasn’t talking about any other EV company. I was thinking about: 1) Six Sigma and quality control in production management given article CLEARLY stated GM had to revise its battery manufacturing process a few times. Really?! So GM had to learn AFTER real live feedback as in let’s experiment on live customers. That is BUSH LEAGUE planning and manufacturing. 2) Redundancy, fail-safe, and margin of safety: How one bad cell in 280 cells ruins the remaining 279 good cells and kills the battery pack. Now, that is retarded and WASTEFUL. Image if NASA used GM’s approach when building a rocket or spaceship. You think about the RATIO of how little that one battery cell costs to manufacture and it’s ability to DISABLE a car costing $37K+. That is some horse sh*t logic GM is using. Keep in mind, the author is not alone. Other Bolt owners have gone through similar if not comparable situations. In summary: I was commenting on GM and solely GM without any regards to other EV manufacturer. I am sorry you got butt-hurt if my opinion is that… Read more »

Nah. Jason, your first comment is a dumb comment.

Are you shorting GM? And exactly how much Tesla Kool-Aid did you drink today?

Why would anyone short GM

GM is poorly managed and is going through a lot of turmoil and confusion. The BEV revolution is going to cost them more and more as time goes on. They are in last place in the big boys auto world.

You could say Telsa is poorly managed too. Going bankrupt, and the worse quality on the planet…

Perhaps if you weren’t shorting Tesla stock, Mr. Serial Tesla Basher, you wouldn’t jump to the conclusion that someone else is shorting GM stock.

It is quite understandable, if you remember that ALL the cells used by GM’s Battery Packs are simply wired in Series. How Tesla deals with challenges like this, is with the 2 or 3 rows of some 15-21 or so lower capacity cells, first Electricly bonded in a circuit, in Parallel, before bonding them (Electricly) in series. GM does basically what any EV Conversion done by an individual or small shop typically does, with a straight and simple series pack wiring design. Those types by design, have this flaw, if any cell is a weak link. On the other hand, way back in 2007 or 2008, the UBC EV Club, Electric Volkswagen Beetle Conversion, used LiFePO4 cells, @ 160 Ah each, wired in 3’s in Parallel, then of those sets, 32 in Series! That gave them some safety and redundancy, for their drive across Canada, from Pacific Coast to Atlantic Coast! My own imagination for My Electricfly new pack, settled on 5 of the 15 Ah Headway Cells in Parallel, and 32 of those, in Series. 75 Ah x 96+ Volts, for a little 7.5 or so kWh Pack. It never came to fruition, for a number of reasons. But,… Read more »

You’re mistaken. The Bolt has 288 cells in 96s3p configuration — 96 cell-groups connected in series where each cell-group containing 3 cells wired in parallel, grouped into 10 modules arranged in 5 sections with two modules per section.

3p means if one cell of three cells die (either fuse or just prematurely age to zero capacity), the remaining two will allow only 2/3 of the charge to pass through it, and this limit affects the other 95 series.

So far it looks like the cells have a very low failure rate, but it could be a problem over time. Having more in parallel would be better.

I have often puzzled at Tesla’s use of very small cells, but there does appear to be a significant reliability advantage, since failure of a single cell (which blows the interconnecting wire/fuse) has little impact on the module which has so many cells in parallel. And the small cans take away the need to squeeze the larger pouch cells, apparently. The fact that Tesla can assemble so many small cells in a cost-effective process is interesting, I doubt anyone else has mastered that yet.

The reason why the Bolt’s pack behaves differently than Tesla’s is the number of cell. The Bolt has 288 cells whereas Tesla uses thousands. So one cell out of 288 is different than 1 cell out of 3000.

So one cell in the Bolt goes bad (out of 288) and it basically renders the pack ‘no good’?

/unlike Tesla which ‘should’ be able to isolate a bad cell (or cells) and keep the integrity of the remaining pack ?

That’s about the size of it. Though the Tesla pack may still need to be replaced, it won’t “Brick” like the Bolt does, though there have been cases of user abuse with Tesla’s where the packs were run down and left for a week or so and would not charge, most of these cases were due to failure of the 12 Volt battery, without which the car will not start. Hint: keep your 12 Volt battery within suggested parameters, also good when posting to inside evs.
The Bolt is pouch batteries, considered to be an inferior configuration for certain aspects of a battery pack:

“Prismatic & Pouch Battery Packs. … Its specific energy is often lower and the cell is less durable than Li-ion in the cylindrical package. Pouch Cell Battery Pack Inside Application. Swelling Pouch Cells. … It is best not to stack pouch cells but to lay them flat side by side. Prevent sharp edges that could stress the pouch cell as they expand.” GoogleSearch etc…

The Bolt battery doesn’t brick anymore, after their software updates.

Did you even read the article? They made a software change so the vehicle can continue working, but with less range. That doesn’t sound like it made the whole pack inoperable.

GM is definitely bush league. You start from the top with a BEV Cadillac and work down from there once the engineering is solid and reliable. Prices then start coming down.

If things go wrong with the initial Cadillac you are only dealing with (lets say) 10,000 Cadillacs not 500,000 BOLTS.

Do Not Read Between The Lines

They’re not making 500,000 Bolts. They have the Bolts they need for compliance and other uses like autonomous vehicle research.
It was _never_ going to be a volume vehicle. This is the springboard, not the pool.

It’s more than a compliance car and outside of Tesla, the Bolt is the number 1 selling BEV in the US.

Compliance cars aren’t sold in all 50 states.

We have the EV1, the fleet S10 EV, the Gen1 Volt, the Spark EV, the ELR, the Gen2 Volt and the CT6 PHEV…Supposedly next is the Bolt based Encore yet maybe they axed that with the restructure…

They did try that with a Cadillac version of the Volt. It hit the streets like yesterday’s news. Nobody wanted it. The Bolt was more of a toe in water approach, you go as cheap as possible, cheap out on the seats, interior, and rear suspension, body design, just use whatever, and hope people overlook that for the superior powertrain, you plug in supplied by LG Chem. They want you to accentuate the positive and ignore the negative. Plus they lose money on it, so it was never intended to be mass market, sold in specific locations, CARB states, big rebate provinces, and very few others. The European version the Ampera, axed. First they raised prices 5k, on it, and then probably delivered 3 or 4 hundred, before deliveries were canceled, breach of contract. All involved with the PSA takeover. Look it up: They were losing money on it but, I think they actually did pretty well with the vehicle, though I think in the long run it was better to do it right, and lose even more money on each one sold, though now GM is going to, or say they will or have addressed some of the… Read more »

“Nobody wanted it”. They sold 1 1/4 x more Caddy ELRs (only made for 12 months), than the Tesla Roadster – made over several years. I seem to be only one of the few mentioning that.

But everyone wants to believe:

1). Absolutely no one bought an Electric Caddy
2). The volt isn’t an electric car, even though it travels more miles on electricity fleet-wide than the Nissan Leaf did in the US.
3). The Honda Clarity is ugly – although it is Oriental Styling meant to appeal to a world-wide taste.
4). Tesla’s are the most efficient with electricity than any other make when actually the opposite is true.

Then of course, you get into Pseudo-Science – but then the 4 items I listed show how constantly repeating ridiculous statements take on a life of their own, as propaganda ministers have always known.

Well, you can’t say nobody bought an ELR because I bought a 2016 ELR w/sport suspension. Best driving car I’ve ever owned. Best looking, best interior, most creature comforts, etc. Been told that by several Tesla owners. Only runs 6.4 sec 0-60 but out handles and with the 14″ Brembo brakes out stops any other EV including Tesla!! It’s not an EV it’s an EREV (Extended Range Electric Vehicle.) That’s the nice thing about it, if I want to drive over 300 miles I can. It doesn’t take long to put the 9 gallons in it and I could drive 3000 miles if I want. I drive long distances in remote areas where there are no chargers so I would be stuck for days waiting for an EV to charge on a 120 volt circuit. I’m telling you guys this because since only 534 of them were made and probably less than 100 with sports suspension, I’m sure 99% of you have never seen one in person let alone driven one. There were no road tests on a 2016 version let alone one with the sports suspension. It was a big mistake for GM to quit making them.

So you are saying Six Sigma and quality control in manufacturing are only needed before the item gets into production. Because it is so good that you’ve eliminated all issues at that stage, and don’t need to worry about things like continuous improvement while you are in production? Wow.. That’s not how I understood that to work myself… 😉 It sounds like these are issues that had been discovered in a small percentage of vehicles and were addressed. That they are continually improving the processes they have as they move forward. That sounds quite a bit like SIx Sigma and quality control to me. I will agree tho, their quality control process wasn’t perfect initially. Too bad..

theflew I had a 2012 Tesla S 85. It had one cell go low 3.9 or so with all others at 4.1 or better. The car would still drive but I could not charge on Level 1,2 or Super Charge. I GURU in my area dropped the pack, found the low cell and by passed it. It ran great after and I could never notice any range loss. The S 85 has something like 7,100 cells.

The Guru said he had only seen one other like that and did the same bypass. This was not at a Tesla service location since it was over warranty. I’m sure there have been others and will be some in the future.

That’s the difference. Tesla uses thousands of cheap cells whereas most of the others use hundreds of more expensive cells – they are not suppose to fail.

Well that’s good news for you and those looking to buy a used Tesla. Hopefully, that fix will work for more folks if necessary.

Is it possible to replace a cell in a Tesla battery pack instead of removing it from the circuit?

Not easily, they are glued/foamed in place with lots of thermal paste.

Yes. Tesla is known to refurbish Model S/X packs, so it is indeed possible and has been done by Tesla.

How do you figure? They’re #2 in EVs. Teslas are on flatbeds all the time and easily get battery replacements at a similar rate.

Oh no I’m getting voted down for saying something bad/true about Tesla. Yet still, no answer to my question.

I lost the thread of what you were saying Cecil T. What did you say that was bad/true about Tesla? Truth sometimes is, as you know, hard to find.

And when Tesla battery cells have failed, they resulted in Tesla car-b-ques, which is much worse than a temporarily disabled car.

You’re not merely a troll, you’re a boring troll, regurgitating old B.S.

Those who are worried about getting caught in a car fire should know they are at least three times safer in a Tesla car than in a gasmobile.

Those who are worried about getting caught in a car fire should know that the Bolt has not had any battery fires, while Tesla cars have had numerous battery fires.

Those interested in statistics should know that the oldest Bolt is barely two years old and fewer Bolts were sold last year than any full year of the Model S, X, or 3 sales. Also people should know for the sake of comparison that the Chevy Volt caught on fire after routine NHSTA crash testing.

Also, has there been a Model 3 fire yet?

The early volts (prior to ALL VOLTS getting a recall and getting a robustification) , would catch fire after 3 days in the collision shop, which incidentally is NOT THE PROPER PROCEDURE – as it is known that a volt in a collision should be immediately discharged.

That is some what different to Some teslas starting fires in a garage (memories of Fisker), starting fires while merely driving, or having the car totally melt down at a Supercharger, with the car owner not being able to do a thing other than watching his car turn into a fireball, then crap on the asphalt pavement with batteries shot out everywhere.

But the “GOOP” in between the ‘3’s cells seem to be drastically reducing Tesla’s propensity to spontaneously catch fire. –>> Anytime there can be well behaved batteries and not having to dodge projectiles just HAS to be an improvement to safety.

Too bad Tesla never hired you Pushi ==>> you’re an excellent ‘Junk Yard Dog’ for them!

Anyone outside of Russia, towing a Tesla to charge it up, knows that is not covered by the warranty, so any towing is done on a flat bed truck!

It doesn’t have to be because the battery failed, it could also be because the owner failed, to fully charge it, or stop and charge it, when he or she, should have! Or, they hammered the suspension in an extreme Pothole! Or, they hit a Deer! Still gets a Flatbed Ride!

Funny thing about having money… It doesn’t always indicate great intelligence!

Some of the smartest folk make some of the dumbest mistakes, too! See NASA Space Shuttle Launch Failures, for some examples! Or Airline Pilots, landing on Taxiways, or Crossing Live Runways while Taxiing!

That mistake wasn’t a smart person. The decision was made by a suit, not an engineer. You work in a company. You’ve seen suits over ride techs, most often flippantly.

The shuttle blew up because they launched it with temperatures outside of design window. They were told to abort and didn’t.

Same with the re-entry crash. The suits keep cutting corners on refurbishment of heat shield tiles.

GM, Tesla, and Nissan are the definition of the EV big leagues, and it’s been that way since 2010. Everyone else is playing in the minors.

Glad to see that they appear to be taking the issue seriously and making corrections. Not like the battery degradation issues many early Volts are seeing, and which GM is trying to hide with software updates to reduce usable battery and range.

“GM, Tesla, and Nissan are the definition of the EV big leagues, and it’s been that way since 2010. Everyone else is playing in the minors.”

Oh please!! Any argument that Nissan is in the EV big leagues is horse sh*t! Just ask the consumers in Arizona who bought the Nissan Leaf in good faith and ended up with an EV whose battery did not do well in the Arizona sun!!

Perhaps CCIE was unaware of the massive number of battery degradation cases from numerous Arizona Nissan owners.

My comment is: If you want to be in the EV big leagues, get your product right!

Jason- Nissan has sold enough cars to be exactly as CCIE said they were.

I’ve been around here too long to be unaware of much.

I wouldn’t buy an EV without a liquid TMS, but Nissan has taken EVs seriously enough to be considered big league (that may change with Ghosn being ousted).

Well actually, Tesla didn’t join the big leagues until the Model S showed up in 2012.

Nissan is ripe to send to the minors.

“The minors” is where Nissan sent Carlos G.?

It’s all bush leagues, from here on out, for “innovation that excites”.

You are correct…GM is not in the EV big leagues…lots of talk, very little prudent investment. The VOLT was a real stupid move. The BOLT was introduced long before its time.

First: The ball full of money should have been thrown to Cadillac, demanding they develop a long range, reliable EV that was ONLY a BEV throughout!
Second: A design team should have been established to develop a Model 3 challenge. sans batteries and drive train.
Third: A design team for a pickup should have been established, sans battery and drive train.
Fourth: Once Cadillac’s drive trains and batteries were perfected, the technology could be installed in a ready designed Model 3 & pickup.

GM stumbles down the path and takes every division and byway therein. It is amazing how badly Mary Barra runs the company.

Maybe you should write them a letter and share your expertise.

Yeah another big expert – but I agree with him that Cancelling the Volt was unbelievably DUMB. They can’t allow the slightest loss – yet won’t put the Voltec system in big CUV that REALLY WOULD SELL. They were SO CONCERNED about every penny with the VOLT, but spending $Billions for Fuel Cell Technology development was a ‘wise business decision’? If they can throw money away like that they can gamble a bit on some decent electric vehicles, which the (former) Volt certainly was.

So many downvotes for an obviously true statement? If GM is ready to play in the EV big leagues, where is their charging network? Why are they buying cells, packs, motors, inverters, every essential part for an EV from LG Chem? Why are Bolt sales down sharply year over year? How has GM secured the huge battery supplies they will need like VW Group, Toyota, and Tesla have?

GM is about to sell their 200,000th EV in America and trigger the countdown on their tax benefits for buyers. Unlike Tesla, they failed to build the infrastructure which would now allow them to have lower production costs than new competition in EVs has, so they will just be fighting for buyers at a $7,500 disadvantage. With the awful seats on the Bolt, they would need a $7,500 advantage to keep it selling once the Kia and Kona and $35,000 Model 3 are here.

Sept. 18, 2017: I learn of additional Bolt drivers (including a pregnant woman on a busy Los Angeles highway) who were stranded on the roadside. Wow too bad she wasn’t also a single mom, that would have really made her special. Always have to add stupid distractions.

This article made me realize we need flat bed electric tow trucks to service EV’s. I bet the telsa semi-truck would make a good flat bed tow truck.

I would think you would want something more reliable than a tesla to tow unreliable teslas.

Your Tesla break down often, Greg? I don’t personally know a single person who has had actual drivetrain reliability issues.

I’m sorry for the trouble you had but it yielded a greatly informative article! I am not yet an EV owner but I have my eye on the Kia Niro EV

My 2nd Bolt’s battery pack has diminished from 60 to 48 in <year.

Are you sure it’s not a Leaf?

Nope. 2017 fully equipped Chevy Bolt Premier, Starbust Orange

Do you have some documentation of the degradation? Would be interesting to analyze what is going on.

Do you have any degradation on yours, Bro?


Honest question…he’s a straight shooter so I’m sure he’ll tell if anything.

Nah, you’re just trolling like you always do.

I would have asked you but you have no knowledge of anything ev. I said it many times that i don’t like the design of the car but for the right price i will get one. It’s not like i have too many to choose from anyway….and need one this year to replace my eGolf.

If my Torque pro app + OBD2 reader is to be believed with its unofficial battery capacity reader, I have currently 56.5 kilowatt-hours of usable capacity. But it fluctuates with the ambient temperature. A month ago it gave me a reading of 59. So after almost 36,000 miles there’s probably a little degradation but it’s not much

Nov 2016 build btw.

I’d say take her in then

How many miles now?

“Decreased from 60 to 48 in a year” … What is the detail Golgoth? Have you tried letting the battery charge up fully a few times so that it can ‘recover’ some capacity? As I say I was down to about 52 kwh, yet now I’m back up to 57 1/2 kwh after 39,000 miles – which I’m happy with since the long term rating of the battery is 57 kwh.

My 01/18 build Bolt had to have the pack replaced at 1300 miles, shortly after they did the software update recall because of an underperforming cell. I never experienced the sudden loss of propulsion, but I also didn’t deplete the battery very far in that first month of ownership. Currently have over 16000 miles on the new battery and haven’t seen any cells that are significantly different in voltage from the rest of the pack.

How would you see if cells have different voltage?

Torque Pro and an ODB-II reader with the PIDs to query for the cell voltage. I took this screenshot of the app before they replaced the battery:

Was supposed to be fully charged but one of the cells (#21) wasn’t even close.

PIDs were from here:

I Also use Torque Pro and the Chevy PIDS. It was only about $5. I have read battery capacity on Bolts, Volts and Spark EVs. It’s a great tool. Most EVs are doing great. But there are for sure a few with problems it’s just hard to see.

The “usable battery capacity” PIDs (there are a couple out there), are not a foolproof way of determining actual usable capacity left. But it is a good way for tracking your Bolt’s capacity reading over time. If when new, your Bolt read 59 kWh, and 2 years later it’s reading 55.5, odds are there has been some slight degradation, though it doesn’t necessarily mean your Bolt’s usable capacity is actually 55.5 kWh.
I’ve experienced swings of +/- 2 kWh within a few days (like one time where it went UP to 59 from 56.5)


Thank you for your original article, and this great followup. Your lack of bias is very refreshing.

Our Bolt is a 12/16 build, and thanks to you and others we had both software updates, and have run Torque Pro since last June. Very interested to see that the defective cell was out by a over a tenth of a volt. We have one cell that consistently runs a hundredth of a volt above the average reading, and one that consistently runs a hundredth of a volt below the average. They have never deviated.

I am the guy on the forums who has been complaining about never having 60 kWh usable capacity from day one.

I am happy to report that whatever they have done with the BMS algorithms, in driving tests our battery’s usable 100% to 2% driving range has increased to ~57 kWh, and the Torque Pro battery capacity, at 59.3 kWh, is at its highest reading ever.

At 18 months, and over 19K miles, I find having 95% of advertised new capacity acceptable.

Excellent user feedback, and vigilant Bolt battery monitoring and assessment. The reported 5% battery degradation is probably about the average/mean for a Bolt with 18 mo. / 19k mi.

“We have 280 cells in a Bolt.” So a single bad cell results in a 0.35 % loss of capacity provided it did not kill other cells. In contrast, the 2,170 cells in a Model 3 means one bad one is 0.046% loss of capacity. In effect, the Tesla battery has nearly an order of magnitude resistance to a single cell failure.

It doesn’t seem to work that way – a single bad cell made the entire battery useless in this case.

Having 280 cells requires cell matching at time of manufacturing, and balancing during charging through the life of the vehicle, of 280 cells. Having 2170 cells means cells matching, and balancing, 2170 cells.

So why is the Bolt sales growth not keeping up to the Model 3s?

“Which is a BIG problem for scaling. As is typical, Tesla’s vehicle is overly complex, with far too many parts, including and especially the battery pack. LG’s flat pack, is more compact, far simpler to maintain, and in the entire scheme of things will have a much better ability to scale as volume increases, with a much steeper drop in price. ” Dude, you got it wrong. It’s about resistance to failure and NOT about complexity versus simplicity. Based on this article, I was made aware the Bolt had 280 cells and if one cell goes bad, the entire battery pack does not work. That is to say in plain English: The Bolt had 280 chances to go bad and render the battery pack unusable. That is retarded!! Whoever gave the approval at GM to have a battery system where it is only as good as the crappiest / worst battery cell needs to be fired! Again, it’s about designing an EV that is safe (not like GM using live customers to confirm their sub-par battery chemistry) and having a design that is highly resistance to failure. Being highly resistant to failure is INDEPENDENT of having complex or simple process… Read more »

Your assertions are not based on current evidence but on wishful projections.

“Whereas, GM will be selling hundreds of thousands of Bolts in only a few years, “

Given GM’s 100 years of manufacturing expertise when exactly do you expect them to be able to scale to 50,000 Bolts per calendar year? They are in CY 4 now. Is this the year? Those manufacturing ignorant Teslans with their unscalable design managed that feat in CY 2. In fact those feckless Teslans actually topped 100k in their first full calendar year and are on track to deliver hundreds of thousands in their second full calendar year.

Seriously? What are you smoking?

You beat me too it! Not even worth reading past where he misstates the kwh capacity of the Model 3.

Wow, what a collection of FUD and outright lies. Bravo, what an achievement in disinformation! (slow clapping) 🙄

Tesla’s battery packs are generally acknowleged to be the lowest-cost, per kWh, in the industry. And getting cheaper by the month.

Tesla’s battery packs, unlike GM’s, are engineered to deal with malfunctioning or failed individual cells, by automatically cutting them out of the circuit.

“Whereas, GM will be selling hundreds of thousands of Bolts in only a few years…”

Seriously, dude?!? I am continually amazed at the willingness of clueless people to demonstrate their ignorance in such a public manner on internet forums. *Sigh*

Hopefully GM will design a new BEV — or several BEV models — intended to be made and sold in high volume. That certainly won’t ever happen with the hastily cobbled-together Bolt EV!

* * * * *

As far as Tesla’s cars having “far too many parts”… after his teardown analysis of the Tesla Model 3, Sandy Munro has been absolutely raving in his praise, and calling himself a Tesla fanboy, over Tesla’s success at reducing the number of parts in the Model 3, and improved efficiency in the powertrain, as compared to his teardown analysis of the Bolt EV and the BMW i3.

> The Panasonic Tesla combination, has zero chance of scaling well, and also won’t drop much in price.

Explain that, and how does that statement compare to what the scale Tesla has achieved so far, as the largest battery manufacturer?

No, it means you have 4,416 points of failure instead of 288. 2170 is the cell size. The battery only has the capacity of the weakest module, I think the bricks are 46 cells each? Meaning a single cell failure would drop the capacity of the pack up to 2% or so (I would have to look more at how the packs are wired, which are parallel and series, etc)

The point is the more cells you have, the more cells you have to keep in balance. The less cells you have the less cells you have to keep in balance. However, with less cells it becomes more important that you keep them in balance. Less cells means larger cells with a greater internal resistance, which makes it more likely the cells are to become out of balance.

The original Bolt software didn’t make range accomodations for a specific cell failure mode and that was why people were getting stranded. I drove for 4 weeks after getting the update and the immediate notification about an underperforming cell and never had issues. My reported range after the computer update was probably 20% less, but it seems like they did as much as they could to mitigate the issue once it was known.

I agree with everything you said except the internal resistance. No reason for a large cell to have different internal resistance than many small cells.

I see three key differences between Tesla and others:
1. With 46p, one cell fusing/aging only kills total charge throughput by 2%

2. Note the “newspaper” comment by the GM engineer. Electrodes in cylindrical cells are in low stress with no folding.

3. Roll to roll is obviously the cheapest way to manufacture and use films in any industry. I expect production machinery to be cheapest and most durable when working with cylindrical cells.

Internal resistance is relative to the physical size of the cell. Assuming we are comparing the same battery chemistry, the larger the cell, the greater the internal resistance. Greater IR means less efficient due to heat loss. It’s why you don’t see individual lithium cells bigger than 1000 Ah. An 18650 cell of the same chemistry will have a lower IR than a 21760 cell of the same chemistry.

Wow, that’s a strange way of looking at things. There’s also built in redundancy, so if there’s failure you won’t notice it.

The difference is the quality of the cell. The Bolt cells are higher quality by design because a failure is a more serious condition. Tesla brags about how cheap their cells are made and at very high rates.

Very detailed notes. Thanks for sharing and sorry to hear what you had to go through.

Didn’t like that Chevy and the dealer ignored the issue in Dec’18-Jan’19. You were clearly an educated customer and had the data to prove it.

A well known editor of a EV website , if GM ignored him, what they will do to average customer, only god knows.

It’s not a one in 1 million event when it’s occurred for one car in 43,000 sales.

That’s not how statistics works

Statistically not enough points, however 43,000 Bolt EVs are over 1 million cells, so probably a reasonable claim.

I thought he meant happening twice to the same person is one in a million

Tim Grewe: “We were the first ones out there with these high-range electric cars.”

Really?! I could have sworn that a company named Tesla sold high-range electric cars way before GM did.

The first ones from GM…or from their department. 🙂

Shhh! Tesla has been making and selling high-range electric cars since 2008. But don’t tell him that!
😀 😀 😀

Note his words more carefully “these”, meaning Cheap(er) EV’s with over 200 Miles range, some 7 Months before first Model 3’s were delivered! But, still are behind Model 3 sales (of just 2018, Q4) in their sales totals!

Do these problems also affect older Volts?

I appreciate this level of transparency. Great interview!

Excellent interview from any perspective.

So in summary, for some reason, people find this article as reason to trash the company that actually motivated GM to build both the VOLT and the BOLT, as well as the ELR, the latter two of which were supposed to eat said company’s lunch.

Oh, and GM gets to blame LG, it’s all LG’s fault.

It is quite notable that so much intense Tesla bashing is posted here, in response to an article that’s about GM’s cars; an article which doesn’t contain the word “Tesla” anywhere.

I guess GM fanboys are really feeling the heat from Tesla’s growing success, hmmm? Well, they have good reason to be nervous. Doesn’t excuse the trolling, though.

GM came to the table and has developed it’s EV tech. I have nothing against Tesla other than missing an opportunity to provide CCS chargers at customer cost at Supercharger locations in order to proliferate EV use and access. Why we get into camps and trash each other instead of cheering on EV development is beyond me. The Chevy Bolt is a great car. PERIOD. The Tesla cars are great cars. PERIOD.

I think GM managed this pretty well and this driver is just unlucky.

However, it does highlight a more disjointed supply chain and issue correction process where GM have to work through LG Chem rather than owning the battery pack themselves, as with Tesla’s vertically integrated model.

How is this any different than Tesla getting bad cells from Panasonic?

It sure seems GM did right by the customer on this. And to provide that much access to a senior engineering manager is also impressive (although being an IEV writer probably helped!).

The problem itself seems like a straightforward process refinement issue. They took immediate action to identify the problem, implemented a mitigation plan, then corrected the root cause. Even with all the documented battery replacements, it’s still a pretty small number for a new technology implementation.

Pretty good effort all in all.

I bought my 2017 Bolt in February 2017 and haven’t had a single problem with it. But now this article has me scared…

You are worried about a 0.01% failure rate? Surely you have something more important to worry about.

That’ll teach you…Lease next time!

Lolwut @bro1999

Are you from the Get FUD school of replying? lolwut indeed, as I have no clue what you are responding to.

As consumer reports has stated for decades and me for years, one should never purchase or in this case even lease a first year redesign of a vehicle or even worse the first year of a new model. CR n other sources always show that the first two years of a new model and redesigns have far more recalls, trouble spots, problems, etc.
I gambled a bit n leased a late 2018 bolt…no problems thus far

Sure is true for the 2011-2012 Leaf. The 2013-2015 is solid.

I thought the same thing but my 18 had this issue. Never got stranded but I could have.

Thank you for the detailed recount of your experience. If it makes you feel better, there are two of us. Bolt 2017 with about 55% of battery charge briefly displayed a message “propulsion may be reduced” and a few minutes later it stopped in the middle of the freeway and had to be towed away. The battery indicator switched momentarily from 125 miles to 40 miles and then immediately to 10 miles and the car could not be shifted to Drive, displaying message “Condition not correct to shift.” I was fortunate to be alone in the car without my family, stuck on the freeway after dark as cars around me were going full speed. The dealership replaced the battery pack, but after replacement I get maximum between 150 and 160 miles on full charge. My repeated appeals to the dealership for the fix and multiple conversations with GM Customer Assistance produced no result. I keep hearing from GM and the dealership that the car is operating within specifications, and that nothing can or will be done about it. The claim is that range can be reduced due to my driving style and weather, which does not make sense since in… Read more »

This is stunning. So one single cell in the Bolt EV battery pack going bad, means the pack has to be replaced?

If so, then why doesn’t this happen far more frequently? Are the cells which GM uses really 99.999% or better free from defects? If so, that’s a real tribute to LG Chem’s quality control!

Anyway, Tesla car owners can be glad that Tesla’s battery packs have always been designed to automatically cut a single cell gone bad out of the circuit, and continue operating with minimal loss of power/energy. Of course, that doesn’t mean that nothing ever goes wrong with a Tesla battery pack; the electronics may malfunction. In fact, to be fair, pack replacement (under warranty) may be more frequent for Tesla cars than it is for Bolt EVs.

Pu-Pu said:
“Anyway, Tesla car owners can be glad that Tesla’s battery packs have always been designed to automatically cut a single cell gone bad out of the circuit, and continue operating with minimal loss of power/energy.”

That’s complete BS and Tesla fanboi fantasy. The Tesla, like the Bolt, would need to have just the defective cell replaced or bypassed. Read jim stack’s comment above. When a single cell in his out-of-warranty Model S went bad it did NOT “automatically cut” the bad cell from the circuit. The bad cell stayed part of the circuit and he could not charge the Model S at all. He had to drop the battery, find the bad cell, and manually bypass it. If he didn’t do that, the Model S would be inoperable once the battery drained, because he couldn’t charge it.

It doesn’t mean the whole pack has to be replaced, but that is simpler to do at a dealership service center, then taking the pack apart and replacing the bad module/cell.

Beta testing on customers is A GM perennial. Half baked products and brand kills, mega bucks into corrupt politicians coffers, less for R&D.

Tesla does the same.

So marry Barra lied about not replacing bolt batteries. I’m not surprised though, I actually found her initial statement hard to believe.

No. Her quote was taking out of context, as is mentioned in the article. Additionally, the dealers may have replaced at the pack level, becuase that’s a simple swap. But the Bolt EV battery pack is modular, so the pack the dealer pulls out is sent to GM, where they likely replace the bad modules, and put the pack back into service after testing.

Maybe this is just another example of how the Bolt is a test platform for GM. It sounds like they made some important improvements to the batteries so this shouldn’t happen again.

But more to the point, GM wouldn’t want to be selling hundreds of thousands of EVs to mainstream buyers if the technology is still raw and this was sort of thing was prone to happen. These sorts of failures could potentially turn people off to EVs entirely. By keeping the Bolt production low and selling only to the most hardcore and forgiving buyers, they effectively get themselves some much needed beta testers to help iron out the technology so that is ready to go mainstream.

Viewed in that light, GM’s lack of desire to increase Bolt production starts to make sense.

I’m sure they have never replaced a LS motor or a tremec gearbox

I had the transmission replaced in my 2011 Cruze eco twice. First time I was driving down to FL for vacation and stopped being able to shift out of 6th gear somewhere around Tampa. I had just filled up with gas so kept driving for over 200 miles. Finally reached my off ramp near my destination and had the car towed. They overnighted a new trans to me and got it back in the car before I had to drive back north. That one failed about 50,000 miles later in the same manner. Over 60k miles at the time but my car was in the era of 100k mile warranty so it too was replaced. Third trans had a different design than the first two. It happens. Sometimes people get unlucky with rare defects.

GM called me a few weeks ago about the low voltage issue and replaced my battery. I had about 20k miles on it. Took about a week. Had an ICE loaner. Definitely do not miss going to gas stations!

I think it happened to me too, although on a smaller scale. My Bolt was manufactured in May 2017. After my first and so far only service in 2018 that included a software upgrade, my range rarely goes beyond 200-miles. When the car was new my range regularly exceeded 250-miles after a charge. Now, I feel fortunate to get close to 200-miles. Cold weather definitely affects range although not for 20% or more range reduction.
I am glad this is a leased car and not a purchased vehicle. When the lease is up Tesla will be getting another new order.

This is a perfect illustration of why the vast majority of drivers are still hesitant to adopt EV’s. The author here did some incredible research on his own, and through some seriously determined “poking” of the powers that be at GM was finally able to get his issue solved. But the avg driver trying to get to work or the grocery store isn’t going to put in anywhere near this level of effort. The apparent need to be an engineer/CSI detective just to own and drive an EV is off-putting. The different charging standards, the different battery tech.., it’s all a bit overwhelming for folks who just want to go from point A to point B.

Until these things are as simple and worry-free as gassing up the minivan for a road trip, mainstream adoption isn’t going to happen. I do believe we can get there, and will, but the timeline looks to be frustratingly long.

Lots of ICE lemons in the world. It’s not unique to EVs.

The BOLT will require a long time to pass, before all the bugs are worked out. Tesla started out with an established design and long tested battery many years ago. The BOLT will cost GM a lot of money. In all probability it will wear out its welcome in the marketplace long before they re-coup any of their money.

You’re not special. Our Bolt is now in the shop as I type for the last 2 weeks getting it’s second battery pack as well. Eerily, your timeline is almost exactly the same as mine. I didn’t wait until the OnStar notifications. Chevy “reset” the battery in Dec, I drove it another month and came back and told them my range was diminished to ~90 miles on a full charge.

@ phi,
Please share your Bolt Model Year (manuf. date) and miles driven, as it is a good reference, and helps reveal a more accurate perspective for others who may be considering a Bolt Lease / Purchase , thanks!

@William, I don’t know the specifics of manufactured date (don’t have the paperwork in front of me), but we purchased it right when it was introduced to the mid-atlantic region. Purchased 5/2018 if that makes a difference.

If one cell dies it takes down the whole pack? I would hope that is not the case because they use hundreds of cells. I would think they would designed a way to isolate the bad cell and keep it from effecting the other 200. Working on laptops and laptop battery packs I know this is the same thing that happens with them. If a pack stops holding a charge one of the cells is bad. Replace it with a 3$ replacement and it can last years longer. I hope they dont plan on making you get a new pack because one of the cells fail. This will be an expensive learning experience.

Yes, according to my service advisor, a cell went bad in our Bolt and now the whole battery had to be replaced.

Easier for them to replace the whole pack at the dealer. But the system is modular. So they will likely send it to GM to repair it, then reuse it.

A side note: It is interesting that the Bolt is charging to nearly 4.2V per cell. I think users would be wise to use the so called “hill top reserve mode” to limit charge SoC for their daily commute.

Being able “to limit charge SoC” in a closer range to 4.1V per cell, may be the better battery longevity charging strategy.

I wonder what SOC Battery University would suggest in this particular Chevy Bolt daily driver commuter use case?

Active cell balancing in the bms would solve cell imbalance issue. This spread of cell voltages in your graphic is common for lithium manganese cells.

“Dec. 2018 – Jan. 2019: I unsuccessfully try to wrangle Chevrolet and a local dealership to pick up the car for service. Chevrolet Communications tells me that my car is safe to drive – although with diminished range.” THIS! THIS IS THE EXACT BS THAT I’M TALKING ABOUT WITH DEALERS! Everyone tries saying that dealers don’t do this, that when you buy through a dealer they’re going to treat you right because they’re a local business or whatever. You have a car that’s less than two years old with fewer than 12K miles on it, still under warranty, performing at under 50% and your dealer (and Chevy) could not care less! You don’t even have to contact Tesla – they automatically dispatch a tow truck bringing a loaner to you, but your local dealer, after you freaking tell them about the issue (even after you’re paying for OnStar! What on earth is the point of paying for OnStar if GM doesn’t even preemptively take care of you!) you’ve got the GM and the dealer bickering with each other about who should actually be the one taking care of you. Why are you taking the car back from them? You’ve clearly… Read more »

Not special in the least.
No problems no complaints
Apr 2018 Bolt

Huh, better go short GM’s stock, right? No demand! Compliance car!

Seriously though, they can’t even be bothered to go pick up a customer’s car that makes them fear being stranded on the side of the road at any moment? They are forced to drive it 25 miles to the dealer? You would think their unicorn case would get the utmost attention and service. And how impressive is it really when they look so hard at their manufacturing techniques and still have similar problems in the very same car?

Tesla is certainly not perfect, let’s be clear. But for a case like this you would get the car picked up and get a nice loaner. Also the only Tesla batteries that have failed *from daily use* over time are cars that get pounded for two years with supercharging and rack up 300,000+ miles. If the Bolt doesn’t have this wear and tear problem so far, it’s because no one would want to buy it to use as a long range fleet vehicle. It’s also a lot easier to have less problems with a car model when you only sell maybe 20k of them annually.

To his credit, his story does hang together. My only issue is, can’t the pack be designed to be more tolerant of one low cell? If the health of the pack depends so critically on absolute uniformity of manufacturing, it’s not very resilient. Any electrical engineer knows you design circuits so that they operate with a small, but finite variability of voltages and currents.

That is not how it works, unfortunately. If a cell has some failure, and is self discharging or consistently low due to high IR, it will bring down any cells in parallel with it. In series, the pack is only as good as the weakest link, be that a whole module or a single cell.

If a cell is this low, its indicative that there is a real problem with it. Wise to not keep pushing large amounts of current through it.

Personally I would not buy a all electric, I would buy a plugin hybrid for that very reason at least you should be able to limp home or off to a safe place if the ICE or the batteries go south.

Great Story !!

I am glad that GM is working on it. I just think they are being a bit disingenuous (or even lying) about things. First the “never replaced a battery pack” and then this wonderful quote: “We were the first ones out there with these high-range electric cars.”

That seems rather strange since the Tesla Roadster and the Tesla Model S and the Tesla Model X were all 200+ mile range cars and all predate the GM Bolt.

In addition, they are claiming that getting telemetry from the cars is some amazing advancement and yet that is what the Model S and X (and 3) all do and have done since day one.

I think Tesla’s dedication to cylindrical cells as opposed to pouches is probably connected to the pressure issue, not just cooling. In the cylindrical cell you have a round metal casing, a metal tube basically, that can handle pressure changes due to temperature and so on. With pouches inside a rectangular cell, this is harder to do.

You should’ve asked them to swap your car with the Bolt EV that Mary’s driving to work occasionally.

As the owner of a 2017 Bolt (though mine is one of the later builds) hearing about these issues makes me nervous.

Though when you think about it I guess it would be better to have a major failure that would guarantee a pack replacement than to lose 20% or more of your capacity over time and not have it covered under warranty.

Some people have range anxiety, I have “degradation anxiety” especially with the lack of options GM provides us for protecting our batteries from high heat and charge levels (thankfully the 2019 Bolts do have the latter issue solved).

Bradley, Can I interest you in a job as software QA person? I wish all JIRA (trouble tickets) were written up like that.

I have a Chevy Bolt now, and it is frustrating that the car itself doesn’t indicate to the customer what is the state of health the high voltage battery. The range indicator is a composite of weather conditions, recent driving power demand and battey health. My predicted range varies between about 220 miles and 310 miles depending on weather and my type of recent driving. I can average the predicted range myself and get a general idea if the battery is doing OK, but knowing for sure would make me feel much better. I had a Nissan LEAF before which did have a battery health indicator which did prove useful (especially since fhe LEAF battery deteriorated fairly rapidly). It is too bad GM is apparently too timid to accept possible [negative] public relations consequence of providing a real-time battery health indicator and customers see the battey doesn’t last forever. (Those pesky customer having unrealistic expectations!). I miss the LEAF Spy mobile app; too bad there isn’t an affordable equivalent for the Bolt. I took a look at the FleetCarma web site and something tells me I wouldn’t like how much their solution would cost. I would like to have better… Read more »

Go buy a model 3. Tesla batteries last more than the life of ICE cars.
On average, Teslas reach 190,000 miles with 90% of its original range.

My 2017 Bolt has, within the last couple months, been full charging to anywhere from about 215 to 230 miles. Before that, it was either at or above 238 (once to 281) It’s not a big deal now, but I’m watching to see if there is a further drop possibly indicating bad cells. Sorry to hear about that problem and here’s hoping it doesn’t happen to too many more people, including me, because I love the car overall!

The Bolt’s range estimator is based on recent driving history/HVAC use. So going purely by the range estimate to calculate degradation is not reliable.

Just like MPG on the DIC for gas cars. It’s just a guess.

Not quite comparable.

It also allows manfacturers wiggle room to duck warrantee issues. like Nissan changing their software to replace less packs.