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Discussion Starter · #1 ·
I have a 2105 with about 155k miles on it. Recently I get a CEL when it is charging. I had an issue with a bad connection on the vehicle receptacle and have fixed this. I often get waiting to initialize, propulsion reduced ect. 12v battery is new. I just get a generic code with torque pro. I bought a nano and I am having issues getting the software to work so no information from that regard. I was suspecting the battery dying but no dead cells it appears. Do these values look ok? This is about 40% charge. I recently had a drop of range from 38 to 32 miles also.
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Not sure why you chose to measure the charge at ~40% SOC, but I believe the meaningful numbers are at fully charged and fully depleted. It was previously stated here that the max deviation should be no more than 121mV. If the switchover from battery to ICE occurs when any one cell drops to a certain trigger, you can't one or two cells causing the switchover early or your range will drop from 38 to 32 miles.

I don't know if you analyzed your graph, but the first and last (#96) cells appear not to have registered. Also, the minimum value cell is supposed to be #51, but it looks like #52 on the graph. Likewise, the max value is supposed to be #6 but it appears as #5 on the graph. That, for me, wouldn't engender a great deal of confidence in the test.

Edit: Corrected max deviation to 121mV.
 

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Discussion Starter · #3 ·
Not sure why you chose to measure the charge at ~40% SOC, but I believe the meaningful numbers are at fully charged and fully depleted. It was previously stated here that the max deviation should be no more than 13mV. If the switchover from battery to ICE occurs when any one cell drops to a certain trigger, you can't one or two cells causing the switchover early or your range will drop from 38 to 32 miles.

I don't know if you analyzed your graph, but the first and last (#96) cells appear not to have registered. Also, the minimum value cell is supposed to be #51, but it looks like #52 on the graph. Likewise, the max value is supposed to be #6 but it appears as #5 on the graph. That, for me, wouldn't engender a great deal of confidence in the test.
The 40% just happened to be where it was at. I was looking for a deviation and I assumed it would be there regardless of state of charge. I will use the battery tomorrow and take another reading when it switched over to gas. I have no idea why the one cells did not read. I figured it is a fluke in the software. I did not look close to see the bars do not line up with the highest and lowest reading but yes that is odd also.
 

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Yes, Those values are good. However, you should make the observation at the point where the battery switches over to Charge Sustaining. The voltages of the cells will be lowest at that point (~3.5 ish volts) and any weak cells will be obvious. The spread should be no greater that ~131 mV I believe. My sense is that your battery is good with only an 8 mV spread with a 40% charge.

I believe that the app has a glitch in that it does not show cell #1 nor cell #96, at least mine doesn't.
 
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Just wanted to mention that one of the basic mygreenvolt app functions will show the min/average/max cell voltages of the whole pack (see the "settings" menu to have these cell voltages displayed on the dashboard). That gives you an initial look at the variance at no cost.

Ideally, the 96 cell groups in the Gen 1 battery pack will be fairly well balanced after the battery is fully charged, as well as when the state of charge has dropped to the bottom of the "usable window" and the system switches to range extending mode. If the mygreenvolt app dashboard display of the "overall" min/average/max cell voltage readings shows an excessive difference, you can then make a purchase from within the app to view the individual cell voltages to determine which cells might be problematic.

Jaryd Carvell, the "friendly neighborhood volt tech" from the Volts Owners Facebook page, has written: "Each of the 96 cell groups should always be between 3.45v - 4.05v, and all cell groups should be within 0.121v (121mv) of each other. However if any voltages go outside of the acceptable range for even a millisecond, it will set a DTC and the check engine light will illuminate. If your light isn't on, then everything is within range."
 

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Just wanted to mention that one of the basic mygreenvolt app functions will show the min/average/max cell voltages of the whole pack (see the "settings" menu to have these cell voltages displayed on the dashboard). That gives you an initial look at the variance at no cost.

Ideally, the 96 cell groups in the Gen 1 battery pack will be fairly well balanced after the battery is fully charged, as well as when the state of charge has dropped to the bottom of the "usable window" and the system switches to range extending mode. If the mygreenvolt app dashboard display of the "overall" min/average/max cell voltage readings shows an excessive difference, you can then make a purchase from within the app to view the individual cell voltages to determine which cells might be problematic.

Jaryd Carvell, the "friendly neighborhood volt tech" from the Volts Owners Facebook page, has written: "Each of the 96 cell groups should always be between 3.45v - 4.05v, and all cell groups should be within 0.121v (121mv) of each other. However if any voltages go outside of the acceptable range for even a millisecond, it will set a DTC and the check engine light will illuminate. If your light isn't on, then everything is within range."
Thanks for the quotation, Wordptom. I searched for it in vain before posting and had to rely on my (faulty) memory for 121 mV (not 131 mV). I forgot that his quote was on the Volt Owners Facebook page.

I've observed the dynamic operation of the battery while driving and I believe I have seen momentary spreads in access of 121 mV (even as high as 180 mV, IIRC). Perhaps there is a time interval involved, or some other parameter that is required before the system reacts to the spread (not withstanding Jaryd's statement). I'll have to double check on my next drive and "circle back on that".

EDIT: "The Circle Back"
Try this experiment: observe battery status with MyGreenVolt while driving normally. Observe the voltage spread. Then, rapidly accelerate (punch it to the floor). You will immediately see a spread that can reach ~282mV or more, definitely beyond the 121mV limit. Then, aggressively brake. Again, observe the spread. Again, you will see momentary value exceeding the 121Mv limit. And, yet, you will not experience a DTC.

I believe that possibly the 121mV limit is applied only when cell balancing is performed.
 

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Discussion Starter · #7 ·
Yes, Those values are good. However, you should make the observation at the point where the battery switches over to Charge Sustaining. The voltages of the cells will be lowest at that point (~3.5 ish volts) and any weak cells will be obvious. The spread should be no greater that ~131 mV I believe. My sense is that your battery is good with only an 8 mV spread with a 40% charge.

I believe that the app has a glitch in that it does not show cell #1 nor cell #96, at least mine doesn't.
Here is charge sustained readings.
I suspect I have a bad connection in the communication bus somewhere. Sometimes torque pro can not establish communication with the vehicle. The car started in reduced propulsion mode when this was happening and then reduced propulsion went away.

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Here is charge sustained readings.
I suspect I have a bad connection in the communication bus somewhere. Sometimes torque pro can not establish communication with the vehicle. The car started in reduced propulsion mode when this was happening and then reduced propulsion went away.

View attachment 172578
Well, there goes my theory! Your battery looks very good.

Now I'm confused as to why Reduced Propulsion is invoked. I can't see a cell going bad momentarily and then getting back into perfect shape.

Are there other reasons for Reduced Propulsion...anyone?

Are you saying that Reduced Propulsion comes and goes? I guess that you did say that. Perhaps a momentary break in connection at a connector is being interpreted as being "low voltage". I would begin checking connections, beginning with the last known connection problem that was "fixed".
 

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Discussion Starter · #9 ·
Well, there goes my theory! Your battery looks very good.

Now I'm confused as to why Reduced Propulsion is invoked. I can't see a cell going bad momentarily and then getting back into perfect shape.

Are there other reasons for Reduced Propulsion...anyone?

Are you saying that Reduced Propulsion comes and goes? I guess that you did say that. Perhaps a momentary break in connection at a connector is being interpreted as being "low voltage". I would begin checking connections, beginning with the last known connection problem that was "fixed".
My additional issue at the moment is the J1772 was stuck in the car and i literally had to break them apart. I am currently waiting on both pieces before I can charge from the wall again. I am wondering if this has been causing an issue for a while. I will update this Saturday as I should have both installed. Currently I have a CEL light on as the car receptacle is not in place I suspect. Driving just fine on MM and normal
 

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Discussion Starter · #10 ·
Here is the voltage with full charge. I put a new receptacle in the car and new clipper creek charger. Part way through the charge I had an unable to charge error. I will have to get my nano working to see what the codes are but the main battery looks good to me.
172597
172598
 

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Here is the voltage with full charge. I put a new receptacle in the car and new clipper creek charger. Part way through the charge I had an unable to charge error. I will have to get my nano working to see what the codes are but the main battery looks good to me.
View attachment 172597 View attachment 172598
I agree. This looks like a heathy battery.

EDIT: I see that your phone battery was charged up to 100%.
There is an app "AccuBattery" that has a settable alarm that will sound when reaching a level below 100%, reminding you to unplug, thus increasing your battery life. I use it on my phone and have set the alarm to go off when the charge reaches 80% of full.
 
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its easy to spot one bad cell compared to the others
but if all cells are bad they will look the same across the board, but have a lower overall voltage from new
my guess
 

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its easy to spot one bad cell compared to the others
but if all cells are bad they will look the same across the board, but have a lower overall voltage from new
my guess
From what I have seen, all cells have not gone bad at the same time. I'm not saying that this scenario is impossible, just that I haven't seen that happening in my (very limited) experience. One or two cells, yes, all of them, no.
 

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Here is the voltage with full charge. I put a new receptacle in the car and new clipper creek charger. Part way through the charge I had an unable to charge error. I will have to get my nano working to see what the codes are but the main battery looks good to me.
View attachment 172597 View attachment 172598
If you want, you can display the min/av/max cell voltage readings on the mygreenvolt app Dashboard.

At the bottom of the choices in the android mygreenvolt Settings menu is one for allowing you to choose which PIDs to display. You can select the option to display the cell min/av/max voltages. Then you can see on the bottom right of the Dashboard the same min/av/max cell voltages shown on the Battcell display screen (i.e., you can view the min/av/max cell readings to see if they are acceptable, and then pay to view the individual cell readings if they are not).

Note, too, the "usable" SOC display at the bottom left of the Dashboard, here showing 100% (10.9 kWh)... does that 100% display reading convey any useful information at all? What’s the raw SOC % when the usable SOC is 100%? When it is at 0%? Should I expect this to show 0% when the battery is depleted?

I can’t find any information in the mygreenvolt materials that describe what this reading is intended to show. Is the app estimating that this Volt’s "usable window" holds 10.9 kWh for Electric Mode driving? Or is that just a preprogrammed number based on the driver’s input identifying the model year of the Volt? Is it a number based on the app’s estimate of the current full battery capacity (i.e., if the 65% Electric Mode window is 10.9 kWh, then the current full capacity is 10.9/65% = 16.8 kWh, or 98% of the 2015 Volt’s original 17.1 kWh when new).
 

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Well, there goes my theory! Your battery looks very good.

Now I'm confused as to why Reduced Propulsion is invoked. I can't see a cell going bad momentarily and then getting back into perfect shape.

Are there other reasons for Reduced Propulsion...anyone?

Are you saying that Reduced Propulsion comes and goes? I guess that you did say that. Perhaps a momentary break in connection at a connector is being interpreted as being "low voltage". I would begin checking connections, beginning with the last known connection problem that was "fixed".
Let’s see... If you run out of gas while driving in Hold Mode, you’ll trigger a Propulsion Power Reduced episode. If you drive up a steep mountain road at 80-90 mph while driving with a fully depleted battery, you’ll likely trigger a PPR episode. If you are driving a Gen 1 Volt with a fully depleted battery that has lost 10% or more of its full capacity over the years and stop to run an errand, if the engine is still running when you turn off the car, you may trigger a PPR episode by pulling power from the battery when you try to restart the engine.

PPR episodes, especially when not accompanied by a malfunction light, are kind of like stubbing your toe or banging your elbow... unlike arthritis in the joints, there’s nothing really wrong with your toe or your elbow, you just did something that caused a sharp pain in your toe or elbow that’s warning you not to repeat what you did that resulted in the stubbing of your toe or the banging of your elbow... The PPR is the vehicle’s method of telling you to not do something (don’t run out of gas, don’t keep so little power in the battery buffer when driving aggressively while extending the range)... and if it’s accompanied by a malfunction light, then the conditions under which it occurred should help locate the problem that triggered the PPR. Metasys Tech’s battery cells appear to be in decent shape, so it almost appears as if the PPRs could be triggered by the same problem that is triggering the CEL (perhaps a code reader would provide a clue). Perhaps a momentary break in connection at a connector is being interpreted as a loss of battery access, so performance is reduced to allow the car to be driven to where the problem can be repaired.

I’ve finally relocated a comment I once read in an old thread that seems to be applicable to Jaryd’s 121 mV spread limit...

In a thread started in January of 2015 discussing the gm battery degradation test procedures, WopOnTour, a very knowledgeable forum participant, responded to the question, "wouldn't differences in the cell voltages I mentioned be a good indicator of a bad cells problem?" by saying:
" No generally they would not .
Observing a 0.01-0.03V variation on a scan tool and especially in the absence of triggered voltage DTCs, would be considered perfectly normal. In fact, depending on conditions even as much as a 0.05V or more observed variation might be considered OK. This is because it will depend on exactly WHEN this instance was indicated , where within the pack the variation is observed, and under what specific conditions.

Was it during charging? discharging? hot/cold soak? before/after cell balancing occurred? etc etc
ALL of these can affect the observed cell group's (triplet) differential voltage and therefore ALL of these conditions are taken into account within the diagnostic routines used to establish when there actually IS an issue. So in a nutshell IF your Volt wasn't triggering cell variation DTCs THEN there isn't any significant variation present WHEN IT MATTERS."

As I understand WOT's comments, the system is constantly gathering data and running diagnostic routines to monitor the operation of the car. At any given time, the readings might be anywhere... so a greater than 121 mV variation will trigger a DTC only if it happens WHEN IT MATTERS. If it happens at other times, it does not. (I offer this example: your engine is running, you drive over a speed bump rapidly, and bam! The gas sensor jumps with the bumping, and the system interprets the interruption in the data as saying there’s no gas in the tank, but instead of triggering a PPR episode because you just ran out of gas, the data obtained at that moment DID NOT MATTER, so no PPR episode.)

Another question is asked, "What are some of the data indicators of battery pack problems?" and WopOnTour responds:

"Quite simply as far as individually monitored PIDs that one might be able to monitor on GDS2 and scan tool or some other CAN device, and used as a metric representing pack, group, or cell state of health- THERE REALLY ISNT ANY! The process is simply too complex to rely on simple point-and-shoot analysis if such individual data points.

Once a DTC is triggered however, that's when we KNOW something abnormal WAS observed under a precise set of enabling and failure criteria. Then and only then might some of these PIDs be used, but only under the conditions as detailed by the diagnostic and often only as a technician observable verification/corroboration of the diagnostic software's indicated detected fault."

Further information is available in this 2015 thread on battery degradation, and more information on cell balancing can be found in a 2014 thread:


 

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if all the cells degrade together you will not get a one bad cell sernario, so looking at the millivolt difference in cells is not at play here
maybe run the battery down to 1kw left in battery and take the car out and floor it , when it reaches 120kw in power then check to see what your lowest cell voltage voltage sags to
there must be an overall low battery voltage set point that may be tripping
 

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Discussion Starter · #17 ·
I was able to get the nano working finally and cleared out all codes to start from scratch. While poking around I saw this crazy temperature. This can't be normal right? 188 Deg F.
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Discussion Starter · #18 ·
I was able to get the fault to show and it is Hybrid Powertrain Control Module 2 P0AF8 Hybrid/EV System Voltage.
 

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And that code means that there's too much voltage difference between the main battery pack and EITHER the HPCM bus (that is, the chonky wires between the battery/HPCM2 and the HPCM1/inverter for the drive motor controllers) if the car is on, OR the expected output from the charger if the car is off and supposed to be charging. (That yellow light when you first plug in? That's when the charger is trying to match voltages with the pack. If it can't do that for some reason after some period of time (and there's a whole diagnostic tree about determining why it can't), it will set P0AF8.)
 

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Discussion Starter · #20 ·
And that code means that there's too much voltage difference between the main battery pack and EITHER the HPCM bus (that is, the chonky wires between the battery/HPCM2 and the HPCM1/inverter for the drive motor controllers) if the car is on, OR the expected output from the charger if the car is off and supposed to be charging. (That yellow light when you first plug in? That's when the charger is trying to match voltages with the pack. If it can't do that for some reason after some period of time (and there's a whole diagnostic tree about determining why it can't), it will set P0AF8.)
The code only happens when charging. How often do the chargers fail? Is there a way to test It or simply wait for complete failure?
 
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