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OK everyone, this is kinda urgent -- my car is in the shop today. It literally is about to go over to 100k and I took it in to get the main traction battery checked, and some other, minor problems.

The dealer service department called and said that they checked for error codes and that the battery is ok, however they said that there is no real 'test' procedure for the main battery that they could give me a printout on.

I vaguely recall that someone on here posted images of data print-outs from a dealership test done on his Volt's main traction battery, showing the condition of the battery.... A bunch of numbers, to my untrained eye.

What exactly was that test and printout? I cant find it and would like to be able to ask the dealer to do X-test on the car to get the info.

This is really important to me because the warranty is just about to die.

Yesterday I got a little over 21 miles on a charge, so while there are no fault codes on the battery, I'd like to get a better, more detailed idea of its actual state of health before the warranty ends.

GM has no test procedure?
 

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OK everyone, this is kinda urgent -- my car is in the shop today. It literally is about to go over to 100k and I took it in to get the main traction battery checked, and some other, minor problems.

The dealer service department called and said that they checked for error codes and that the battery is ok, however they said that there is no real 'test' procedure for the main battery that they could give me a printout on.

I vaguely recall that someone on here posted images of data print-outs from a dealership test done on his Volt's main traction battery, showing the condition of the battery.... A bunch of numbers, to my untrained eye.

What exactly was that test and printout? I cant find it and would like to be able to ask the dealer to do X-test on the car to get the info.

This is really important to me because the warranty is just about to die.

Yesterday I got a little over 21 miles on a charge, so while there are no fault codes on the battery, I'd like to get a better, more detailed idea of its actual state of health before the warranty ends.

GM has no test procedure?
There is no formal battery "state of health" test procedure the dealership can perform.
The SOH of the battery is tied into some rather complex DTCs.
If they are not set, your battery Is fine

Besides, it's winter time in Illinois isn't it??
Under winter conditions 21 miles be neither unexpected nor unreasonable
Some people in Canada have reported even lower than that, but only for a few days during extreme conditions

Can't wait till spring ! ;)
WopOnTour
 

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The warranty statement about the battery is on page 15 (shown as page 19 in a PDF reader). It basically implies GM will only cover battery energy capacity loss of greater than 30% at the end of the warranty period. Nobody has ever mentioned capacity losses anywhere near that level so you are unlikely to be the first. I've got 106,000 miles of which 65,000 is from EV driving on the battery and my user-perceivable losses are minor, if any.

Still, there should be an official test and the warranty implies that it takes about a day to perform.

Here's the 2014 warranty doc which presumably the same for older cars:

http://www.chevrolet.com/content/da.../Warranty/02-pdfs/2k14chev_lim_wm2ndprint.pdf

[WopOnTour inserts the following comment into the middle of my post]
As I said there is no formal test per se
The day long period referred to in the warranty statement simply reflects the time required to complete the diagnostic as outlined by the DTC where the battery would first need to be fully charged then fully discharged and charged twice to confirm the DTC triggers once again.
WOT
UPDATE: I was typing up my reply when WOT posted his earlier message about there being no general-purpose capacity degradation testing procedure & report so I didn't see that he had already replied. He obviously knows the real answer which is, I guess, that any excessive degradation causes the car itself to throw an error code and the service procedure is simply to put the car through a full recharge cycle or two to see if it throws the same self-test error code again. No error code, no worry.
 

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Yesterday I got a little over 21 miles on a charge
Meaningless, join the crowd. I've seen a few days like that too, especially now that my snow tires are on (an immediate 5 mile penalty). Like we keep saying every fall and winter, the range will return in the spring and summer.

But I do understand your concern, especially if this was the summer, driving at 35 mph with properly inflated tires on a level road on a nice day with few stoplights. But it's winter and cold and the roads are snow messy and the heat is cranked up.
 

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Im in Chicago and get about 25miles a charge. Totally normal. But I agree they should be able to at least print out that there are no codes.
 

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The warranty statement about the battery is on page 15 (shown as page 19 in a PDF reader). It basically implies GM will only cover battery energy capacity loss of greater than 30% at the end of the warranty period. Nobody has ever mentioned capacity losses anywhere near that level so you are unlikely to be the first. I've got 106,000 miles of which 65,000 is from EV driving on the battery and my user-perceivable losses are minor, if any.

Still, there should be an official test and the warranty implies that it takes about a day to perform.

Here's the 2014 warranty doc which presumably the same for older cars:

http://www.chevrolet.com/content/da.../Warranty/02-pdfs/2k14chev_lim_wm2ndprint.pdfAs I said there is no formal test per se
The day long period referred to in the warranty statement simply reflects the time required to complete the diagnostic as outlined by the DTC where the battery would first need to be fully charged then fully discharged and charged twice to confirm the DTC triggers once again.
WOT


2013 Chevrolet Volt - VIN 3491




2013 Chevrolet Volt - VIN 3929




FWIW: An independent testing lab contracted by the U.S. Department of Energy has confirmed a 5% loss of Ah/kWh battery capacity of one 2013 Volt after 70kmi and 3% decrease of Ah/kWh battery capacity of another 2013 Volt after 60kmi! So, thus far the highest government documented Volt battery capacity degradation is still only in the single digits and very far from @30%.


As far as how the testing lab was able to measure this specific battery capacity loss, I have no idea but you could try to contact these folks and find out if they are using a GM scantool or similar I suppose...
 

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Hybrid/EV Battery Pack Capacity Learn

Your dealer can in fact test the battery. One test I have had done is the
"Select Hybrid/EV Battery Pack Capacity Learn"
in the "Hybrid/EV Powertrain Control Module 2 Control Functions" list.

I don't have the printout available to me (I'm away from home), but I remember it showing things like the voltage, kWh, state of charge, some settings, and the most important one is the "Hybrid/EV Battery Pack Capacity" and it is a hexadecimal value that you will have to look up can be converted decimal ampere hours. This value changes with the battery state of charge. There are other threads here on gm-volt.com about this hexadecimal value.

One very important set of values on the printout is the part that helps show if any of the individual cells of the battery pack are bad by showing the average cell voltage and the min and max voltage. My printout values, at 15k miles, were no more than .01 volt difference which seems very good.

Best wishes for learning more about the health of your battery pack.
 

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2013 Chevrolet Volt - VIN 3491


2013 Chevrolet Volt - VIN 3929




FWIW: An independent testing lab contracted by the U.S. Department of Energy has confirmed a 5% loss of Ah/kWh battery capacity of one 2013 Volt after 70kmi and 3% decrease of Ah/kWh battery capacity of another 2013 Volt after 60kmi! So, thus far the highest government documented Volt battery capacity degradation is still only in the single digits and very far from @30%.


As far as how the testing lab was able to measure this specific battery capacity loss, I have no idea but you could try to contact these folks and find out if they are using a GM scantool or similar I suppose...
FYI - The test methodologies used by Intertek an the Idaho National Laboratory is completely documented on the INL website. They did not use any General Motors electronic or scan tool equipment and instead used more conventional battery lab apparatus for their measurements.
WOT
 

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Your dealer can in fact test the battery. One test I have had done is the
"Select Hybrid/EV Battery Pack Capacity Learn"
in the "Hybrid/EV Powertrain Control Module 2 Control Functions" list.

I don't have the printout available to me (I'm away from home), but I remember it showing things like the voltage, kWh, state of charge, some settings, and the most important one is the "Hybrid/EV Battery Pack Capacity" and it is a hexadecimal value that you will have to look up can be converted decimal ampere hours. This value changes with the battery state of charge. There are other threads here on gm-volt.com about this hexadecimal value.

One very important set of values on the printout is the part that helps show if any of the individual cells of the battery pack are bad by showing the average cell voltage and the min and max voltage. My printout values, at 15k miles, were no more than .01 volt difference which seems very good.

Best wishes for learning more about the health of your battery pack.
That is not a capacity test. That is a special function reset procedure to be used under very specific conditions. The scan tool displayed hexadecimal capacity PID is a HPM2 calculated value and integrated into various operational and diagnostic routines and not meant to be interpreted as a "stand-alone" element for SOH assessment or diagnosis.
WOT
 

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Discussion Starter #12

Ah, yes, perhaps that was it -- the printout of the Volt's "Voltage Data Parameters." I would have liked that, even. The dealer is Grossinger Chevy Chicago.

However, alas, they sent me on my merry way, and said the Volt tech had already left for the day so I couldn't talk to him. They stuck to the position that there is no repair shop test procedure for the main battery (other than just finding fault codes generated by the vehicle itself).

Crossing fingers, in about 60 miles I hit 100K.

They charged me $140 to lube a squeaking bearing for the steering wheel. The extended warranty for the steering lockup defect would not cover it :(
 

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WOT - just a note to LG Chem, you, and all GM electrification engineers - GREAT JOB and THANK YOU. Though the INL tests may differ from GM's internal test equipment and procedures, they probably are generally consistent with industry LION traction battery test protocols and show the Volt battery to be rock-solid, even after 60 K miles. I'd think that most ICE engines have lost 6% or more capacity after 60K miles, even with solid service practices. And I bet the Next Gen battery will prove to be as good or better:)

Regarding range loss due to heating, I sure hope Gen 3 offers a heat pump as an option, if not standard equipment. I've got residential inverter-driven air-source heat pump systems running at air temps down to -7 F with 70% of rated heat BTU output and COP of 1.5 to 2.0 At 25 F, COP = 2.5. Those numbers might really help winter range loss. -20 F? OK, a heat pump will cry "uncle" and look for backup.
 

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21 mpg as stated right now is pretty darn good. Also I have found if you keep car plugged in all the time, it is better in the winter. I have only one charger, so one Volt gets left in the cold. I can tell that it uses much more frequent engine running and battery juice to warm up the battery. Esp after sitting a whole day at -6 at work.
 

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How does one drive 100K on a volt and not know that it doesn't go as far when it's cold. And where I'm at its really, really cold.
 

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WopOnTour, please tell us more.
When you speak of resetting, are you referring to the Hybrid/EV Battery Pack Capacity Reset function? It is a separate function from the Learn function.

And wouldn't differences in the cell voltages I mentioned be a good indicator of a bad cells problem? My values were:
Minimum Hybrid/EV Battery Module Voltage=4.02
Maximum Hybrid/EV Battery Module Voltage=4.03
Hybrid/EV Battery Voltage Sensors Average=4.03

What are some of the data indicators of battery pack problems?

Can you tell us anything about what that GM Document 2560214 says? I see you have mentioned it in a previous post on a similar topic.
 

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Discussion Starter #17
Because we only bought it a few months ago -- and I did know it would have reduced range. But dropping from 41-43 in summer down to 21 (EV range) in winter and only maybe 35 mpg on ERDTT ...no, that's rather a shocking drop.
 

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I get 50 miles in the summer if I drive in mild weather with the windows open where AC isn't needed and keep it under 50 mph. In the winter I drop to 25-33 miles with Eco auto at 70 degrees. I found that I get better EV range with ERDTT set to the higher setting, though it's burning more fuel to get that. Of course driving faster makes the range go down. Driving slower helps, but in the winter that means keeping the heat on longer, so it's a wash.
 

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WopOnTour, please tell us more.
When you speak of resetting, are you referring to the Hybrid/EV Battery Pack Capacity Reset function? It is a separate function from the Learn function.Can you tell us anything about what that GM Document 2560214 says?

I see you have mentioned it in a previous post on a similar topic
First of all the battery pack capacity reset/learn (it's a single combined function) DOES NOT in any way shape or form represent any sort of "test" of the battery functionality or state of health as had been previously suggested. This reset/learn function is present in the GDS2 software in the "Module Setup" section and is a special function that both erases the previously stored module capacity value and commences a sequence of subroutines to learn (over time) a fresh value that is stored in HPCM2 memory that represents the existing static capacity (Ah) as a point of reference for numerous activities.

The reset/learn is technically ONLY to be performed when 1 of 3 things have occurred:
- the battery pack has been replaced
- any section of the battery pack has been replaced
- HPCM2 has been replaced

In the "other" thread you referred to, in which I had mentioned this process- this was specifically due to the possibility that the reset/learn was not done immediately following a pack replacement.
Since then steps have been taken (e.g. via technician prompts embedded in the service programming software) to insure the technician performs this reset/learn under the aforementioned repairs have been performed.

And wouldn't differences in the cell voltages I mentioned be a good indicator of a bad cells problem? My values were:
Minimum Hybrid/EV Battery Module Voltage=4.02
Maximum Hybrid/EV Battery Module Voltage=4.03
Hybrid/EV Battery Voltage Sensors Average=4.03
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.

What are some of the data indicators of battery pack problems?
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.

Does this help?

What I really would like to say is relax, don't worry! GM has your back when it comes to these battery packs! Even if you ended up replacing a battery at 150-200K miles (not looking like that will be a common occurrence even) they will do their best to soften the blow for Volt owners. FYI the battery exchange/replacement price is already down to about the same $$ as an automatic transmission overhaul or an engine rebuild.

"Just Drive and Smile"

WopOnTour
 

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Km
Besides, it's winter time in Illinois isn't it??
Under winter conditions 21 miles be neither unexpected nor unreasonable
Some people in Canada have reported even lower than that, but only for a few days during extreme conditions

Can't wait till spring ! ;)
WopOnTour
I live in southern Illinois and over the last month I have seen my daily AER dip as low as 28 miles as displayed on the Guess-O-Meter
Now that it's starting to warm up a bit my AER's are SLOWLY rebounding.

I doubt there is anything wrong with your battery.
 
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