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Discussion Starter #1
Hello fellow Gen1 Volt owners.

I am trying to gather some feedback on GM’s recall for loss of propulsion due to low cell voltage from owners with MygreenVolt app who had taken battery cell readings before and after the software update was done. I recall seeing a thread a year or so ago with a few owners sharing images on this board but am unable to locate it now.


I have 2014 with almost 30k miles now. It was manufactured in 2013, I bought it in 2015 after car sat on the lot for 2 years, so the battery is just over 7 years old now. I‘d never taken the car back to dealership for anything as I’ve done my own oil changes and coolant replacement. I regularly get over 45 miles of range here in NC in summer months and not unusual to see 50 on GOM. I don’t hypermile, but am a pretty smooth driver. The car is garaged and is in really good shape. I’ve observed the used kw go from 10.6 down to 10/10.2 over the years, but my EV miles that I get remained about the same.

Now relative to the recall. I haven’t done it yet and am not sure if I want/need to. I know it is free if I do it before July of 2021. Currently, at the top of my charge cells reading is close to 4.05V with min/max of 11mV between cells #42 and #54, sometimes it reads 9mV, but generally hovers around 11mV.

Could someone share their readings before and after the recall. Or what readings to expect after the software update. I am not sure if min/max of 11mV is normal range, but suspect that it isn’t far off. I’ve seen all the threads of owners permanently losing range after the update, but this may have to do with actual degradation of the battery before the update was done thus reducing usable kw window.

I am still on the fence whether I want to do this recall based on my current readings and am inclined to wait until actual problem presents itself, hopefully many years down the road if ever, so am interested to hear others’ thoughts and how you approach this recall. Thanks.
 

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This is only MY opinion, If you are currently happy with your actual electric range (not GOM figures), the car has no other problems, I would NOT get the recall done at this time. My son currently has my "old" 2011 and I told him not to do it, the car is working just fine. I think he has until December of NEXT year to get the recall, I will most likely have him do it before that expires. I have read way too many posts here with people losing actual miles, just not worth it if everything is working fine. Again, MY OPINION
 

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I had the recall done on my 2012 Volt (bought new in late 2011). The range estimate was consistently around 35 miles before the recall. The estimate was 39 miles just after the recall work was done, and over a week or so the estimate worked its way up to 42 miles. So, I'm happy.
 

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Had this cell balancing performed on my 2012 a week ago. MyGreenVolt reported min/max variance of .01. During warm summer months, I consistently achieved 80+km (2012 GOM displays 80km/50miles max). I meant to take Steverino's advice of signing a waiver to prevent the update, but alas, forgot. I dropped it off at the dealer to check a coolant leak (first vehicle repair, I'll post about later...) at 5am and rode a folding bike the rest of the way to work. When I picked it up to find a full charge of only 60km (ahhh!) I knew the recall was done. Now after a few charges, got 77 this morning. Its cooling down outside so 3km loss is normal. If your cells are well balanced beforehand (<.03), this recall should have minimal effect on your range. Get it done before any loss of propulsion alarms occur as you don't want a potential failure while driving, its kinda of a safety thing.
 

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Jaryd Carvell is a very well respected Volt owner and works as an EV technician at a Chevy dealer in the Chicago suburbs. Here is what he had to say about the recall on FB:

Jaryd Carvell->Hi friendly neighborhood volt tech here! As I have tried to explain to so many people in this group. The recall (GM Program #:N172130462 Issued:Mar 28, 2019) is to correct your vehicle from improperly balancing the cells over time. The balance of those cells is part of what is used to calculate the GOM. When they reprogram the module 2 things happen. The vehicle starts to properly balancing the cells again, and the battery capacity learned values are reset. Over the course of multiple charge/discharge cycles the cells properly balance, and then the module relearns the capacity and the GOM adjusts accordingly. If your GOM goes up or down it means that the car had not been properly balancing the cells for quite some time. This process happens much slower without full discharge/charge cycles and so some people the adjustments happen much quicker than others. Also not all vehicles have the same cell imbalance. Even with the bad software some vehicles were staying close to properly balanced and others were quite a bit off. If yours was one that was close to correct, not much will change after the recall. If your cell balance was off, the more it's going to change after the recall. This is why some people noticed almost no change and others have had a change in the GOM. This is also why some people have seen the change quickly and some it took a while. Complete discharge/complete charge cycles will accelerate this learning process. Oh and one more thing, the 2013-2015 volts have 9 battery temp sensors but really only need 6. There is also software included in the recall that allows the vehicle to ignore up to 3 of the redundant temp sensors if they fail, rather than having to replace them. So there are multiple reasons to have this recall performed.

The kwh used in the power summary screen is only a calculation, not a direct measurement. It can and will vary at times, especially after being reset. If you aren’t getting the same mileage you were before, it's most likely that it was inaccurately displaying higher than it should've before the recall due to improper balancing of the cells. Now that the balancing is fixed the readout is simply more accurate. The recall did not and can not change the capacity of the battery.
 

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Discussion Starter #7
Jaryd Carvell is a very well respected Volt owner and works as an EV technician at a Chevy dealer in the Chicago suburbs. Here is what he had to say about the recall on FB:

Jaryd Carvell->Hi friendly neighborhood volt tech here! As I have tried to explain to so many people in this group. The recall (GM Program #:N172130462 Issued:Mar 28, 2019) is to correct your vehicle from improperly balancing the cells over time. The balance of those cells is part of what is used to calculate the GOM. When they reprogram the module 2 things happen. The vehicle starts to properly balancing the cells again, and the battery capacity learned values are reset. Over the course of multiple charge/discharge cycles the cells properly balance, and then the module relearns the capacity and the GOM adjusts accordingly. If your GOM goes up or down it means that the car had not been properly balancing the cells for quite some time. This process happens much slower without full discharge/charge cycles and so some people the adjustments happen much quicker than others. Also not all vehicles have the same cell imbalance. Even with the bad software some vehicles were staying close to properly balanced and others were quite a bit off. If yours was one that was close to correct, not much will change after the recall. If your cell balance was off, the more it's going to change after the recall. This is why some people noticed almost no change and others have had a change in the GOM. This is also why some people have seen the change quickly and some it took a while. Complete discharge/complete charge cycles will accelerate this learning process. Oh and one more thing, the 2013-2015 volts have 9 battery temp sensors but really only need 6. There is also software included in the recall that allows the vehicle to ignore up to 3 of the redundant temp sensors if they fail, rather than having to replace them. So there are multiple reasons to have this recall performed.

The kwh used in the power summary screen is only a calculation, not a direct measurement. It can and will vary at times, especially after being reset. If you aren’t getting the same mileage you were before, it's most likely that it was inaccurately displaying higher than it should've before the recall due to improper balancing of the cells. Now that the balancing is fixed the readout is simply more accurate. The recall did not and can not change the capacity of the battery.
Thanks for the info!
 

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Well, you’ve read Jaryd’s comments on the cell balancing procedure, suggesting that it is good in the long run for the health of the battery. Keep in mind that older Gen 1 Volts are subject to a couple of related problems. One is the cell-balancing problem, and the other is simple loss of capacity from growing older. These are separate issues with separate treatments. The PPR problems arising from a simple loss of "oomph" are the subject of Bulletin No. PIC6292C, whereas GM program #N172130462 (and N172130461 for 2011 Volts) refers to the procedure whereby the Chevrolet dealer updates the Hybrid Powertrain Control Module (HPCM2) to prevent the gradual loss of the Volt’s ability to maintain voltage (the cell balancing issue).

My understanding is that the procedure to correct the simple PPR problem may indeed result in loss of usable grid power when the extended range battery buffer is enlarged to compensate for the battery degradation (the buffer is ~5% of full capacity, and 5% of diminished capacity may eventually not be enough to maintain performance in moderate demand extended range mode driving conditions). Increasing the "switch to gas" SOC without also increasing the "full charge" SOC reduces the usable window, and hence a drop in kWh Used for a full charge.

The cell balancing programming, however, may not necessarily alter the size of the usable window. I’ve been driving my 2012 Volt for over 8 years now, but as a retired person, I rarely drive more than 10-20 miles per day around town (I do take 500+ mile road trips each summer, which give my generator lots of work), so I rarely experience the opportunity to see my actual "full charge" ev range. I "seem to remember" getting ~9.6-9.8 kWh Used for a full charge during 2018-2019, and then had that cell balancing procedure done in November 2019. Now I seem to be getting only 9.4 kWh Used, but my ev range estimate is up to 43 ev miles this summer (greater than in summer 2019), and have twice recently driven 42+ miles on those 9.4 kWh Used drives. For someone who normally uses 3-5 kWh per day around town, 9.4 kWh usable is very acceptable.

My 2012 Volt battery exceeds my daily ev range needs around town on almost every day of the year, and now that I’ve had the cell balancing procedure done, I expect it to provide me with similar expected performance for some time to come.

More important to me is that the battery may degrade over time, but grid powered miles are but a fraction of the electric mile range of a Gen 1 Volt. Keep in mind the Gen 1 Volt is propelled 100% of the time by the large electric motor, including when the generator is in use (one-motor configuration provides full performance - when "cruising" down the road, the generator may also be clutched to the drivetrain to improve fuel mileage).

By my estimate, my Gen 1 Volt generator creates ~10 kWh of usable electricity "as needed" per gallon of generator fuel burned. This equips my fully fueled Gen 1 Volt with ~100 kWh of available usable electricity, providing it with a range of 350+ electric miles (gas-generated electricity has the same energy content as grid electricity).

While others may denigrate the "authenticity" of electric car propulsion provided by gas-generated electricity, those final few slow speed, stop and go traffic miles of a long road trip that I drive using generator output provide me with the same all-electric performance someone else may get after using Hold Mode for hundreds of miles so they can complete the drive on grid power. As far as I know, the Gen 1 Volt is the only PHEV in the US that can do this. Even the Gen 2 Volt, when extending its range, may transition under certain driving conditions from electric propulsion to internal combustion engine propulsion only.

So if having the cell balancing procedure done will extend the healthy battery life of your Gen 1 Volt, providing you with 100% electric propulsion (less the distance you achieve "cruising" while extending the range) in years to come, especially if any potential modest reduction in the usable window would still meet most of your daily grid powered driving needs, what is the wisest choice for you?
 

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Discussion Starter #9 (Edited)
Well, you’ve read Jaryd’s comments on the cell balancing procedure, suggesting that it is good in the long run for the health of the battery. Keep in mind that older Gen 1 Volts are subject to a couple of related problems. One is the cell-balancing problem, and the other is simple loss of capacity from growing older. These are separate issues with separate treatments. The PPR problems arising from a simple loss of "oomph" are the subject of Bulletin No. PIC6292C, whereas GM program #N172130462 (and N172130461 for 2011 Volts) refers to the procedure whereby the Chevrolet dealer updates the Hybrid Powertrain Control Module (HPCM2) to prevent the gradual loss of the Volt’s ability to maintain voltage (the cell balancing issue).

My understanding is that the procedure to correct the simple PPR problem may indeed result in loss of usable grid power when the extended range battery buffer is enlarged to compensate for the battery degradation (the buffer is ~5% of full capacity, and 5% of diminished capacity may eventually not be enough to maintain performance in moderate demand extended range mode driving conditions). Increasing the "switch to gas" SOC without also increasing the "full charge" SOC reduces the usable window, and hence a drop in kWh Used for a full charge.

The cell balancing programming, however, may not necessarily alter the size of the usable window. I’ve been driving my 2012 Volt for over 8 years now, but as a retired person, I rarely drive more than 10-20 miles per day around town (I do take 500+ mile road trips each summer, which give my generator lots of work), so I rarely experience the opportunity to see my actual "full charge" ev range. I "seem to remember" getting ~9.6-9.8 kWh Used for a full charge during 2018-2019, and then had that cell balancing procedure done in November 2019. Now I seem to be getting only 9.4 kWh Used, but my ev range estimate is up to 43 ev miles this summer (greater than in summer 2019), and have twice recently driven 42+ miles on those 9.4 kWh Used drives. For someone who normally uses 3-5 kWh per day around town, 9.4 kWh usable is very acceptable.

My 2012 Volt battery exceeds my daily ev range needs around town on almost every day of the year, and now that I’ve had the cell balancing procedure done, I expect it to provide me with similar expected performance for some time to come.
This is great info! Thank you for sharing!
 

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One more note. After I had the cell balancing procedure done last November on my 2012 Volt, I drove the car through 11 full charge/full depletion cycles so that the Battery State Estimate Algorithm could calibrate itself using data gathered from throughout the entire "usable window" of power. I used an OBD reader and the older version of the mygreenvolt app (the new android version no longer provides the "raw " SOC readings) to view the raw SOC at full charge when I unplugged from the wall, and the raw SOC at the point where the system switched to gas.

My records indicate the averaged value of the "full charge" SOC for my 2012 Volt was 87.8%, and the switch to gas SOC value was 22.3%. The "usable window" for the 11 cycles averaged 65.35% of full capacity (Wikipedia says the Gen 1 Volt usable window is 65% of full capacity). The cell balancing procedure clearly did not impact the size of my usable window. The kWh Used ranged from 9.1 to 9.6 kWh, averaging 9.39 over those 11 cycles. Math says 9.39/65.35% = 14.4 kWh current full capacity, or my 2012 Volt’s full battery capacity is ~90% of new after 8+ years of driving. (Keep in mind the precision of the data on the displays was only to 1 decimal point.)
 

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Discussion Starter #11
Finally decided to take it in based on responses above. Thank you all who replied. Does anyone know if the battery needs to be fully changed in order to perform this recall? Thanks again!
 

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Your Guess-o-meter will reset to 40 miles, and a new learn cycle will begin. I brought mine in empty and did a full recharge afterwards. Doubt it matters much. The Volt will look after itself.
 
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