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Discussion Starter · #1 ·
2020 Chevy Bolt EV Battery Capacity Anecdotal Observation




After two months of driving a 2020 Chevy Bolt for some 2,000 miles we've found that the traction battery of our car has a capacity of 64 kWh, not the 66 kWh advertised. More interestingly, the 2020 battery pack of our car has only 2.5 kWh more than that of our previous 2017 Bolt. This anecdotal observation may not reflect the rest of the 2020 Bolt fleet.


I've kept a log of our miles driven, kWh used, and other accessible parameters for all the EVs I've driven. For example, I tracked the 2017 Bolt's traction battery capacity with an OBD reader and Torque Pro for much of the time we drove the car. I report on our experience driving electric to encourage others to do so and have written about the 2017 Bolt.


We purchased our 2020 Chevy Bolt in early October 2020 to replace our leased 2017 Bolt. I began a log on the 2020 Bolt immediately upon purchase.




2020 Bolt Blocks Capacity Signal

For some unknown reason, the 2020 Bolt blocks the signal for battery capacity to the OBD reader. I'd used this signal with Torque Pro to track the slight battery capacity degradation of our 2017 Bolt over 2.5 years.


However, we can infer battery capacity by knowing how much percentage of the battery was used for so many kWh consumed between full charges. For example, on a recent trip, beginning with a full charge, we consumed 54.3 kWh and arrived home with 14.1% State-of-Charge. Thus 54.3 kWh/(1-0.141) = 63.2 kWh.



Disclaimer: I worked for GM's Delco-Remy Division 1968-1970 as a cooperative engineering student. I was a member of UAW Local 1981 until the National Writers Union left the UAW in May 2020. The Chevy Bolt is assembled by UAW Local 5960.



Battery capacity varies from charge to charge whether using the car's OBD signal or the inference method above. In the case of the Bolt, the capacity can vary 1-3 kWh per charge cycle.

Bolt's Advertised Capacity

The nominal capacity of the 2017-2019 Bolt was advertised as 60 kWh and that for the 2020 as 66 kWh. However, the actual capacity is somewhat different from the nominal capacity.


Korea's Ministry of the Environment publishes the measured traction battery capacity of EVs as reported by the manufacturer. They report that the 2017-2019 Bolt has 60.9 kWh of capacity and the 2020 has 65.94 kWh. That's a difference of 5 kWh and not the 6 kWh as suggested by the difference in nominal capacity.





Are we splitting hairs here? Yes. The reason is that there appears to be only a few kWh difference between the two battery packs based on my observation of our two vehicles.

Anecdotal Observations

We've driven our new Bolt about 2,000 miles so I'll compare the measurements I've made on the two vehicles during the first 2,000 miles. First, the 2017 Bolt.








The average estimated capacity during the first 2,000 miles is 61.3 kWh. The capacity varied from 59.6 kWh to 63.8 kWh. Next, the 2020 Bolt.





The average estimated capacity during the first 2,000 miles for the 2020 Bolt is 63.8 kWh. The capacity varied from 62.1 kWh to 65.3 kWh.


The difference between the two averages is about 2.5 kWh. At an efficiency of 4 miles/kWh, our 2020 Bolt has 10 miles more range than our 2017 Bolt did. This isn't a significant difference.


Now, let's take a look at the range estimator on the DIC (Driver Information Center), otherwise known as the GOM (for Guess-O-Meter).





The range estimates for the 2017 model averages from 215 miles to 311 miles on a full charge at an average efficiency of 4.3 miles/kWh.


The range estimates for the 2020 model averages from 219 to 315 miles on a full charge at an average efficiency of 4.3 miles kWh.


The difference between the range estimates for the two cars is 4 to 7 miles or the equivalent of 1 to 1.5 kWh at 4.0 miles/kWh. The difference in range is essentially insignificant.

Are the 2017 & 2020 Batteries Different?

The battery packs in both models are made by the Korean conglomerate LG Chem. The battery packs for the 2017-2019 models were made by LG Chem's Korean plant. However, the battery packs for the 2020 Bolts are made by LG Chem's plant in Holland, Michigan.


Are the two packs different? If they are, the difference is subtle and could be partly attributed to the different plants using slightly different components.


Hyundai's Kona EV also uses LG Chem's Korean packs and rates their nominal capacity at 64 kWh.


GM announced this week that it was recalling 2017-2019 Bolts for a problem with their battery packs. Hyundai did as well for their Kona EV. The 2020 Bolt battery packs made in Michigan are not part of the recall.

The Bolt is not a Leaf

To put these numbers in perspective let's compare the 2020 Bolt to our 2015 Nissan Leaf. Nissan advertised the Leaf with a 24 kWh battery. However, only 21 kWh were actually usable. That's a difference of 12.5%. The 2 kWh difference from the 66 kWh advertised by Chevy is only 3% or one-fourth that of Nissan's Leaf actual versus advertised capacity.

Temperature as a Factor

I am discounting any temperature effects. I began the logs on both cars when we began driving them in the fall. Bakersfield, California is not Michigan. Fall here is mild. Though it does get down to freezing at night on occasion, it warms up during the day.


It's not the absolute number of kWh that's important in this comparison; it's the difference between the two vehicles. One vehicle, the 2017 model, reported as much as 3 kWh more than its nominal capacity. The other vehicle, the 2020 model, reported 1 to 3 kWh less than its nominal capacity.

What to Make of This

I am not sure what to make of these observations. I don't see much difference in capacity or range between the two model years.


Am I upset? No, not really. Though we do own the 2020 Bolt as opposed to leasing it. In other words, it's our car, not GM's. We would have bought it anyway if GM had advertised a nominal 60 kWh battery rather than 66 kWh.


Would I prefer 66 kWh over 61 kWh? Yes indeed. However, the difference between what Chevy advertises and what we experience is probably within the normal range of variability of complex manufactured products.


The car delivers what we want. We drive it where we want, when we want. The small difference in capacity doesn't affect how we use the car--not in the least.


I am more disturbed or frustrated with the fact that Chevy has blocked the signal to the OBD for battery capacity. Why did they do that? The implication is that they have something to hide from their customers. In an age of rampant conspiracy theories, why ask for suspicion? Just report the data as you would to any technician servicing the car. Only nerds are going to go to the trouble of plugging in an OBD reader and setting up Torque Pro to read the messages. We're a decided minority of EV owners. And mostly we just chatter to each other. It's not like it's a great scandal that needs to be hidden away from the prying eyes of the public or pesky journalists.

Summary

Based on my observation of the battery capacity of the 2017 Bolt and the 2020 Bolt, there's only a modest increase in capacity for the new model, about 2.5 kWh, and not the 6 kWh that GM advertised.


See also.

Paul Gipe
 

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So your findings appear to bolster the theory that some 2019 Bolts received 2020 Bolt battery packs. The only dissent so far theorized that the (later) 2019 batteries, although likely made at the same MI plant, had a slightly lower capacity than the 2020’s. But if you’re correct and the 2020 batteries are actually lower in capacity than advertised, then it becomes more and more likely that the late-model 2019 and 2020 batteries are, in fact, the same batteries.

Think of it this way: Why would GM introduce yet another variant of the same battery for such a short campaign, when they already had the 2020 batteries ready to go into the 2020 Bolts in just a few months?
 

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Discussion Starter · #3 ·
So your findings appear to bolster the theory that some 2019 Bolts received 2020 Bolt battery packs. The only dissent so far theorized that the (later) 2019 batteries, although likely made at the same MI plant, had a slightly lower capacity than the 2020’s. But if you’re correct and the 2020 batteries are actually lower in capacity than advertised, then it becomes more and more likely that the late-model 2019 and 2020 batteries are, in fact, the same batteries.

Think of it this way: Why would GM introduce yet another variant of the same battery for such a short campaign, when they already had the 2020 batteries ready to go into the 2020 Bolts in just a few months?
I am curious what others think. That's why I put it out there. We could use more data.

I also wonder if the Kona and Bolt batteries are the same.

Paul
 

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I am curious what others think. That's why I put it out there. We could use more data.

I also wonder if the Kona and Bolt batteries are the same.

Paul
Would also be interesting to find out when they started blocking that “battery capacity” reading on the OBD-2 port. You used “bookend Bolts” (2017 and 2020). Did they start blocking it in the 2019 production run (mid-cycle) when they apparently started installing the (fire problem corrected) batteries into the 2019 Bolts? Hmmmm....
 

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@paulgipe Very interesting analysis. My understanding is that GM / LG has over the years evolved the chemistry of the Battery cells to reduce cost and improve performance. As has been posted other places by @GJETSON the attached image is from the GM service manual for the Bolt indicating that there is indeed a chemistry difference from 2017-2018 to 2019 and again from 2019 to 2020.
31889


I would fully expect that with the battery pack being the highest cost component of the Bolt EV much engineering would be devoted to incorporating $$ saving improvements as quickly as possible.

My hypothesis looking at your data set to date is that what you are seeing is more temperature related. The pack is 1k lbs, so the pack temp changes slowly in my experience. It will be interesting to see what you are seeing come spring/summer. Can you look back at your 2017 data set to see if you have a seasonal variation? Any pattern pop out when compared to average monthly temp?

Also, my understanding of the Battery capacity PID is that it is not blocked, but encrypted. We "just" need @Telek or someone to figure out the encode / decode algo. ;) for 2019 - 2020.
 

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So your findings appear to bolster the theory that some 2019 Bolts received 2020 Bolt battery packs. The only dissent so far theorized that the (later) 2019 batteries, although likely made at the same MI plant, had a slightly lower capacity than the 2020’s. But if you’re correct and the 2020 batteries are actually lower in capacity than advertised, then it becomes more and more likely that the late-model 2019 and 2020 batteries are, in fact, the same batteries.

Think of it this way: Why would GM introduce yet another variant of the same battery for such a short campaign, when they already had the 2020 batteries ready to go into the 2020 Bolts in just a few months?
Interesting. I have a 2019 that is not under recall. Presumably the pack was made in MI. The label on the battery says 57 kWh so I'm wondering if maybe it has the 2020 cells but they software limited the pack to 60 kWh? I wonder if there's some way to determine that without opening the pack (which I'm obviously not going to do). Maybe there's a PID that shows the actual capacity or some test that can be done?

Mike
 

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@paulgipe Very interesting analysis. My understanding is that GM / LG has over the years evolved the chemistry of the Battery cells to reduce cost and improve performance. As has been posted other places by @GJETSON the attached image is from the GM service manual for the Bolt indicating that there is indeed a chemistry difference from 2017-2018 to 2019 and again from 2019 to 2020.
View attachment 31889

I would fully expect that with the battery pack being the highest cost component of the Bolt EV much engineering would be devoted to incorporating $$ saving improvements as quickly as possible.

My hypothesis looking at your data set to date is that what you are seeing is more temperature related. The pack is 1k lbs, so the pack temp changes slowly in my experience. It will be interesting to see what you are seeing come spring/summer. Can you look back at your 2017 data set to see if you have a seasonal variation? Any pattern pop out when compared to average monthly temp?

Also, my understanding of the Battery capacity PID is that it is not blocked, but encrypted. We "just" need @Telek or someone to figure out the encode / decode algo. ;) for 2019 - 2020.
Sorry, but that’s not plausible.

You’re saying GM would want to save money for only a partial year run of production where they’re only making 10,000 units???

That’s peanuts to them.

Here’s what’s more plausible: GM takes a page out of Big Pharma’s playbook and slips the 2020 fire-corrected batteries into the 2019 production stream as a “single blind test”. Then they block (and BTW, “encrypted” means “blocked”) the “battery capacity” value through the OBD port. And maybe they do this well in advance of slipping in the 2020 batteries because they know about the problem (well in advance), and what the solution will be (to immediately switch to the 2020 batteries).

Now, why would GM try the “single-blind test”? I don’t know ... maybe they’re considering sabotage? 5 cases out of 68,000 for a mass-produced battery. What did these 5 people do that was so different than what the rest were doing to cause these fires? Just charging to 100% all the time?? For 30+ years, I can count on one hand how many times I’ve pulled into a gas station with my LOW FUEL light not ON! I routinely run all my gas tanks inside 2 gallons remaining. I don’t even consider going to a gas station unless my LOW FUEL light is ON. Sometimes I’m even inside my final gallon of gas! Maybe these 5 people do the same thing with their EV: run it down to within 10% every time, then charge to 100% every time? Could that be causing these fires? If so, you’d have thought LG/GM testing would’ve caught that a long time ago...
 

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I am curious what others think. That's why I put it out there. We could use more data.
I believe you got a better than advertised pack in your 2017, and a worse than advertised pack in your 2020. We got a worse than advertised pack in our 2017. As GM said:

“The 57 kWh number on the battery label is the “rated energy”, a regulatory requirement that represents the absolute minimum energy content (under worse case scenarios), not the energy target. Accounting for typical statistical variation, LGE [LG Electronics] has been delivering the targeted 60 kWh of nominal pack energy”, Bonelli said.

My take is some packs could have 5% more than the targeted 171.4 Ah, or 180.0 Ah, while some could have 5% less, or 162.8 Ah, in the case of a 2017. Making batteries is more like cooking, than making gas tanks.

I have thought about Telek's recent comments, and I think he is right. GM is not artificially maintaining a buffer at the top and bottom of the charge. The 3%-4% the RAW SoC PIDs would suggest is the result of simply not pushing the resting voltage to 4.2V..


He said that the techs he talked to, who check Bolts before delivery with the GM test equipment, are seeing 10-15% lower than the maximum Ah spec in the manual. That means the pack makers are not hitting the targeted capacity.
 

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Discussion Starter · #9 ·
@paulgipe Very interesting analysis. My understanding is that GM / LG has over the years evolved the chemistry of the Battery cells to reduce cost and improve performance. As has been posted other places by @GJETSON the attached image is from the GM service manual for the Bolt indicating that there is indeed a chemistry difference from 2017-2018 to 2019 and again from 2019 to 2020.
View attachment 31889

I would fully expect that with the battery pack being the highest cost component of the Bolt EV much engineering would be devoted to incorporating $$ saving improvements as quickly as possible.

My hypothesis looking at your data set to date is that what you are seeing is more temperature related. The pack is 1k lbs, so the pack temp changes slowly in my experience. It will be interesting to see what you are seeing come spring/summer. Can you look back at your 2017 data set to see if you have a seasonal variation? Any pattern pop out when compared to average monthly temp?

Also, my understanding of the Battery capacity PID is that it is not blocked, but encrypted. We "just" need @Telek or someone to figure out the encode / decode algo. ;) for 2019 - 2020.
Thanks for that chart.

Yes, I have data on the 2017 over 2.5 years. I have an article in process--and it's been in process for months now--on battery degradation in the 2017 Bolt. The reason for the delay is my charting software is archaic and the charts look like xxxx. ;)

Paul
 

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Thanks for that chart.

Yes, I have data on the 2017 over 2.5 years. I have an article in process--and it's been in process for months now--on battery degradation in the 2017 Bolt. The reason for the delay is my charting software is archaic and the charts look like xxxx. ;)

Paul
This should be interesting to look at. My 2018 Bolt's battery degradation data has been collected for about 2.5 years as well and a side-by-side comparison would be nice. I just use Google Spreadsheet and it charts the data immediately, though.
 

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Sorry, but that’s not plausible.

You’re saying GM would want to save money for only a partial year run of production where they’re only making 10,000 units???

That’s peanuts to them.

Here’s what’s more plausible: GM takes a page out of Big Pharma’s playbook and slips the 2020 fire-corrected batteries into the 2019 production stream as a “single blind test”. Then they block (and BTW, “encrypted” means “blocked”) the “battery capacity” value through the OBD port. And maybe they do this well in advance of slipping in the 2020 batteries because they know about the problem (well in advance), and what the solution will be (to immediately switch to the 2020 batteries).

Now, why would GM try the “single-blind test”? I don’t know ... maybe they’re considering sabotage? 5 cases out of 68,000 for a mass-produced battery. What did these 5 people do that was so different than what the rest were doing to cause these fires? Just charging to 100% all the time?? For 30+ years, I can count on one hand how many times I’ve pulled into a gas station with my LOW FUEL light not ON! I routinely run all my gas tanks inside 2 gallons remaining. I don’t even consider going to a gas station unless my LOW FUEL light is ON. Sometimes I’m even inside my final gallon of gas! Maybe these 5 people do the same thing with their EV: run it down to within 10% every time, then charge to 100% every time? Could that be causing these fires? If so, you’d have thought LG/GM testing would’ve caught that a long time ago...
TLDR but yes, I am saying that it's possible that LG changed the battery chemistry twice, or that GM changed the BMS code to use more of the battery in 2020 than 2019. Would not be the first time they used the "golden screwdriver" to alter the specifications.

LG builds batteries for other EVs

If the part numbers are different, the battery packs are different
 

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TLDR but yes, I am saying that it's possible that LG changed the battery chemistry twice, or that GM changed the BMS code to use more of the battery in 2020 than 2019. Would not be the first time they used the "golden screwdriver" to alter the specifications.

LG builds batteries for other EVs

If the part numbers are different, the battery packs are different
OK, so there's a table in a document somewhere that says GM changed the battery capacity incrementally twice: once during the 2019 production run, and then again in 2020. And they may have assigned new part numbers because of this.

Who cares??

That says nothing about how the batteries are internally built. Maybe they threw that out there as a red-herring: You know .. the "Don't look at that ... look at this!" type-thing.

What we know is ... GM is not recalling some of the 2019 batteries for the fire-risk problem; they are being treated just like the 2020 batteries. So that tells us ... as far as the fire-risk problem is concerned, they are the same batteries. They may have different power capacities, but that doesn't matter. What matters is, internally, however those cells were fabricated, GM sees them as safer, and less of a fire risk than the 2017-early 2019 batteries.

So when you say it was about money, I say that's a red-herring, because there's much more reason to believe it was about squashing this fire problem ASAP. And if that's true, they've known about this problem going all the way back to (at least) 2018.
 

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Sorry, but that’s not plausible.

You’re saying GM would want to save money for only a partial year run of production where they’re only making 10,000 units???

That’s peanuts to them.

Here’s what’s more plausible: GM takes a page out of Big Pharma’s playbook and slips the 2020 fire-corrected batteries into the 2019 production stream as a “single blind test”. Then they block (and BTW, “encrypted” means “blocked”) the “battery capacity” value through the OBD port. And maybe they do this well in advance of slipping in the 2020 batteries because they know about the problem (well in advance), and what the solution will be (to immediately switch to the 2020 batteries).

Now, why would GM try the “single-blind test”? I don’t know ... maybe they’re considering sabotage? 5 cases out of 68,000 for a mass-produced battery. What did these 5 people do that was so different than what the rest were doing to cause these fires? Just charging to 100% all the time?? For 30+ years, I can count on one hand how many times I’ve pulled into a gas station with my LOW FUEL light not ON! I routinely run all my gas tanks inside 2 gallons remaining. I don’t even consider going to a gas station unless my LOW FUEL light is ON. Sometimes I’m even inside my final gallon of gas! Maybe these 5 people do the same thing with their EV: run it down to within 10% every time, then charge to 100% every time? Could that be causing these fires? If so, you’d have thought LG/GM testing would’ve caught that a long time ago...
Here's what's even more plausible. GM and LG work together to make the Chevy Bolt EV's cells. They know that they will be transitioning to the NCM 712 chemistry for the upcoming 2020 Bolt EV, but because GM isn't LG's only battery client, LG continues to improve on their NCM 622 chemistry, which they will also be selling to other clients. I imagine the conversation went something like this:

LG: "We've tweaked the NCM 622 chemistry so that the form factor used in the Chevrolet Bolt EV now has 200 Ah maximum capacity instead of 185 Ah."
GM: "Cool."
 

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@paulgipe

For whatever reason, I can't find my early data from my review of the 2020 Bolt EV, but based on close to accurate testing (99% to 4%), the 2020 I tested had pretty close to 65 kWh of usable capacity under 1,000 miles. That doesn't seem far off of what you were recording with your own 2020, but I would expect most new 2020 Bolt EVs to have somewhere between 64 and 66 kWh of actual, usable capacity available.
 

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Here's what's even more plausible. GM and LG work together to make the Chevy Bolt EV's cells. They know that they will be transitioning to the NCM 712 chemistry for the upcoming 2020 Bolt EV, but because GM isn't LG's only battery client, LG continues to improve on their NCM 622 chemistry, which they will also be selling to other clients. I imagine the conversation went something like this:

LG: "We've tweaked the NCM 622 chemistry so that the form factor used in the Chevrolet Bolt EV now has 200 Ah maximum capacity instead of 185 Ah."
GM: "Cool."
That is it exactly, OR LG moved to the NCM712 chemistry but started in 2019 with a conservative setting on the BMS and then programed to use "more of the battery" as long term charge / discharge test results came in. I think it is important to emphasize that you can tweak the anode, cathode, and battery "batter" all while maintaining the same formfactor pouch cell.
 

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For what it's worth (running for full to zero):
My 2017 Bolt was always getting 61kwh+ My 2019 Bolt only get 59kwh (even when new)

NOW my '17 has the recall but NOT my '19!

Could we infer that they were more conservative on the '19s battery assembled in the US (i.e. not recalled)
 

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For what it's worth (running for full to zero):
My 2017 Bolt was always getting 61kwh+ My 2019 Bolt only get 59kwh (even when new)

NOW my '17 has the recall but NOT my '19!

Could we infer that they were more conservative on the '19s battery assembled in the US (i.e. not recalled)
I would be more interested to know if the manufacturing process is well enough controlled to intentionally create that difference.
 

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LG: "We've tweaked the NCM 622 chemistry so that the form factor used in the Chevrolet Bolt EV now has 200 Ah maximum capacity instead of 185 Ah."
GM: "Cool."
Considering all the work that GM puts into qualifying battery designs to make sure they perform as designed under a huge range of environmental conditions and use cases, all while posing no safety risks, do you think they'd really be OK with LG Chem making unilateral changes?
 

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Considering all the work that GM puts into qualifying battery designs to make sure they perform as designed under a huge range of environmental conditions and use cases, all while posing no safety risks, do you think they'd really be OK with LG Chem making unilateral changes?
Yes. As I noted here earlier (in another thread?), the Volt underwent numerous battery design changes between 2010 and 2018, some of them occurring between model years with no other substantive changes. As long as the fundamentals of the battery are still in place, teasing an extra 20 Ah of capacity through slight tweaks can't be that big of a deal to GM.
 

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Yes. As I noted here earlier (in another thread?), the Volt underwent numerous battery design changes between 2010 and 2018, some of them occurring between model years with no other substantive changes. As long as the fundamentals of the battery are still in place, teasing an extra 20 Ah of capacity through slight tweaks can't be that big of a deal to GM.
I'm not questioning whether or not GM would redesign the battery, I'm questioning whether or not GM would be happy with LG Chem redesigning the battery on their own without GM's say-so.
 
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