Gen 1 Volt - Battery Data Log with GDS2

Scott Manager Claremont, California Posted   Latest   Edited  
2013 Chevrolet Volt 1.4L (4 LUU) (4ET50)—1G1RH6E46DU109472
P0A7F - Hybrid/EV Battery Pack "A" Deterioration
Intermittent Low Power
Propulsion Power Is Reduced

Within this resource you'll find a few screenshots from my 2013 Volt which is experiencing a battery issue. This issue surfaced about mid 2018, right after GM introduced a recall on this vehicle. The recall was issued because of a previous calibration that GM released which inadvertently disabled cell balancing. Cell balancing is used during charging to ensure that all the batteries are maintained at the same voltage levels. 

We discovered the recall around September of 2018 and immediately applied the new software. The vehicle has continued to display symptoms related to a failing battery. My range has not really changed, the problem is when the battery reaches the point where the Extended Range ICE is deployed, and after the vehicle is parked for 30+ minutes, after startup, a message appears in the instrument cluster stating: "Propulsion Power is Reduced". This is also accompanied by the ICE running at higher RPM's in an attempt to get the battery charge level to established minimums. After a few minutes, the message will disappear and driving is returned to near normal levels. 

I've been driving the vehicle and logging data as much as I can in an attempt to learn as much as I can about the condition. DTC P0A7F sets intermittently (No MIL illumination) and I was able to log data recently with the GDS2 while recording battery data as reported by HPCM2. I manually added some bookmarks at the beginning of the log to mark where I had made a WOT pull on the freeway. 

When you begin looking at this data, you'll see that GDS2 placed a DTC bookmark (Green trace) where P0A7F set. 

This plot over time shows the point where the DTC set.

This plot highlights the min/max voltage variation that seems to occur as loads change.

Here is the GDS2 Data Export File

Here is the report

I will updating this resource as more data becomes available.

Mike Mechanic
Elysburg, Pennsylvania
Mike Default

My 2011 Volt just started giving the P0A7F code. Did you find out anymore information? Thank you!

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Scott Manager
Claremont, California
Scott Default

Hi Mike, There’s been a calibration update that doesn’t fix the battery, but it applies a new filter so that the MIL doesn’t illuminate unless the voltage variance between the highest and lowest cells extends beyond a greater amount than what was previously defined. You may want to connect your scan tool and log the data as I did above and tried to load the battery when it’s near the bottom…

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Mike Mechanic
Elysburg, Pennsylvania
Mike Default

Thanks for the reply! I have had what I thought was that update for variance but maybe mine is beyond the limit, I will have to check. And what you suggest is what I was going to do next. Thanks again!

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