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I've been using the mygreenvolt app on my phone and have taken a few screen shots. I noticed my battery is not as balanced after fully depleting and letting sit uncharged for a few hours. I usually get a PPR message when starting the car after this, it runs for about 30 seconds and the message turns off, the engine runs a few minutes then shuts itself off with no codes. Pic 1 is right as the cars starts, pic 2 is after the RPP message went away. I just had the recall done about a week ago and have went about 5-6 full charge discharge cycles.
 

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Model year? Mileage?
 

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What year Volt?

After you drove beyond battery range, was the engine still running as you turned the car off and let it sit? Or was the engine not running at that point?

Was pic 1 taken before you pressed the blue button, or after you pushed it and the engine was started? When you start the engine, the Volt’s "starter motor" (MGA) draws power from the battery. The cell voltages before the engine was started should be a little higher than after it was started. If the power you use to start the engine drops the cell voltage levels too close to the allowed minimum, it could trigger a PPR episode without throwing any error code.

What did mygreenvolt report as the raw SOC readings when these pics were taken? Somewhere around 20%-22%? What is the raw SOC reading when the battery is fully charged?
 

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Mileage? Model year?
 

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2012 77,000 110mpg lifetime. I believe the generator had stopped running when I turned the car off. Yes pic 1 before pushing the button to power car on. Pic 2 is right after. I'll check the SOC before and after the next full cycle. Love the car, I can go a little over 40 miles if I really try on the back roads.
 

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OK state of charge starts at %100, when fully depleted it's at %11 then %10 when arriving home a few miles later still says 1.1 kwh left though. Those pics on the first post were fully depleted. Here is right after switching to gas, then stopped in driveway no generator running but fully depleted. I'll have to document the whole process again cuz even I'm getting confused 😂.
 

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I discovered today a Facebook page for Mygreenvolt Users. Some of the entries there provide valuable information on the amount of variation one should see in the cell voltages. One posting from February, for example, says "Battery health is related to a good balance of all the cells. When the car is idle, you should see less than 15 mv difference between the min and the max voltage."

When I asked about the raw SOC readings, I meant the state of charge level of the battery itself. You indicate the state of charge starts at 100%, and then 11% when fully depleted. That’s the SOC for the usable part of the battery, not the raw SOC for the battery itself.

For a Gen 1 Volt, my understanding is that the raw SOC should be around 85%-87% when the battery is fully charged, and around 20%-22% when fully depleted. The newest version of the android version of the mygreenvolt app (the one that provides individual cell voltages) seems to have lost the capability to provide that information. Without the ability to read SOC at full charge and at the switch to gas moment, you can’t tell if the car is still using 65% of the battery capacity when driving in Electric Mode.

The description of the app on the Play Store continues to say it can provide: "Actual and raw state of charge of the battery," and the illustration on the website shows at the bottom left: SoC: 41.4% (45.5%), representing the actual and raw states of charge. It appears this capability continues to exist in the I-phone version of the app. The raw number is not available in the android version I downloaded. The Facebook page does not mention this issue.

Additionally, I question the accuracy of what the app calls the "actual" state of charge of the battery. Today I used an updated android version of the mygreenvolt app. I started my fully charged 2012 Volt (was using the app Setting choice for the 2010-2012 Volt, 16.0 kWh battery). What I saw in the bottom left window of the Dashboard was SoC%: 100% (10.4 kWh). Indeed, 10.4 kWh is 65% of a 2012 Volt’s 16.0 kWh battery, but my battery is 8+ years old, and data I’ve gathered indicate my battery has suffered ~10% degradation over the years. My "100% of the actual state of charge" should now be perhaps 9.4 kWh.

My Volt’s cells seem to be fairly well balanced, with less than 15 mv difference between max and min voltage when fully charged and also when fully depleted.

I myself had the cell balancing procedure done last November on the 2012 Volt I’ve been driving for over 8 years, following which 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 the throughout the entire "usable window" of power.

I used the older version of mygreenvolt app 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 (or as close to that moment as I could stop the car and view the numbers, keeping in mind that once the car is in CS Mode, the generator is running and the SOC is subject to change).

My "full charge" SOC averaged 87.8%, and the switch to gas SOC averaged 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 kWh Used averaged 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.

My older version of the android version of mygreenvolt offers only the max / av / min cell voltage average of all the cells, so one cannot pinpoint any cells with individual variations outside the norm of the others, but since my results indicated only differences of ~10 mv between max and min, my cells appear to be balanced. During my 11 cycles of fully charged/ fully depleted, my average cell voltage at full charge was 4.000 volts, and at the switch to gas point, 3.660 volts. For comparison purposes, your fully depleted, stopped in driveway picture shows average cell voltage of 3.650 volts (nearly the same as my 2012 Volt, but your max/min difference was 25 mv, mine ~ 10 mv).

Perhaps you can gather similar data as you do those full charge/ full depletion cycles. Determine the kWh Used readings for each full cycle, then if you assume your Volt, like mine, is using a 65% usable window, divide the average kWh Used per cycle by 65% to get an approximate value for the battery’s current 100% full capacity (and compare that to the 16.0 kWh of the new 2012 battery). Keep in mind this data is approximate, not precise (perhaps to 1 decimal point?).
 
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