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Discussion Starter #1
Hey everyone! 2012 Volt owner with 110,000 miles. The past two days, I’ve noticed my battery range dropping by about 1/2 mile per hour on the guess o meter while parked unplugged at work. I can guess that it’s not just simply guess o meter weirdness going on, as the battery pack SOC as measured by torque drops about 10% in 4 hours. I did have my hpcm2 reprogrammed last year as part of the “service high voltage charging system” repair, but I did not notice the range dropping while parked in the summer heat unless it was above 90 degrees. Today’s heat where I am was approximately 65, however it was only about 45 degrees overnight so the battery pack started at around 50 degrees this morning, and ended at 59 degrees. Another weird anomaly that may be part of it is I noticed that the temperature sensors for the power electronics loop temperature readout reads 86 degrees regardless of outside temperature, but sometimes it will show -46 degrees before returning to the original temperature. Could the car possibly be thinking it’s overheating and running the AC to cool itself? I assumed it would use the battery temp sensor but I’m not sure. Any suggestions from anyone else who’s maybe had this happen to them? Any ideas are much appreciated!


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Hey everyone! 2012 Volt owner with 110,000 miles. The past two days, I’ve noticed my battery range dropping by about 1/2 mile per hour on the guess o meter while parked unplugged at work. I can guess that it’s not just simply guess o meter weirdness going on, as the battery pack SOC as measured by torque drops about 10% in 4 hours. I did have my hpcm2 reprogrammed last year as part of the “service high voltage charging system” repair, but I did not notice the range dropping while parked in the summer heat unless it was above 90 degrees. Today’s heat where I am was approximately 65, however it was only about 45 degrees overnight so the battery pack started at around 50 degrees this morning, and ended at 59 degrees. Another weird anomaly that may be part of it is I noticed that the temperature sensors for the power electronics loop temperature readout reads 86 degrees regardless of outside temperature, but sometimes it will show -46 degrees before returning to the original temperature. Could the car possibly be thinking it’s overheating and running the AC to cool itself? I assumed it would use the battery temp sensor but I’m not sure. Any suggestions from anyone else who’s maybe had this happen to them? Any ideas are much appreciated!


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Does your Volt still have the original 12V AGM battery? If so these strange readings may be a sign the 12V is failing to hold a charge and needs to be replaced ASAP.
 

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Discussion Starter #3
Does your Volt still have the original 12V AGM battery? If so these strange readings may be a sign the 12V is failing to hold a charge and needs to be replaced ASAP.
It still has the original from when I bought it last spring, I’ll definitely look into that thanks for the advice!


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It still has the original from when I bought it last spring, I’ll definitely look into that thanks for the advice!


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It would be good insurance to have one of the small, inexpensive (under $50) lithium battery jump starters with you in case the 12V battery leaves you unable to start your Volt.
 

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The state of charge part of the E range system has to get its data from some where and may only calculate it on starting the car.
We are talking about a battery system that can change with temperature as it is an Electrochemical storage system.
WOT posted on this in the past

And a $20 power port 12 volt meter will give some peace of mind on the 12 volt battery health over time.
(plus you get to have the HOLY-MOLY - it is charging the battery at 15 Volts :)

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Some of us think the range system is 2 magic eight-balls in series.
 

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It would be good insurance to have one of the small, inexpensive (under $50) lithium battery jump starters with you in case the 12V battery leaves you unable to start your Volt.
Why not just replace your 12V Battery every 3-5 years and not need a portable jump starter. If you have one charged at 100%, after 1 year it will degrade to only hold 80% charge. After 2 years, it will be junk.
 

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Hey everyone! 2012 Volt owner with 110,000 miles. The past two days, I’ve noticed my battery range dropping by about 1/2 mile per hour on the guess o meter while parked unplugged at work. I can guess that it’s not just simply guess o meter weirdness going on, as the battery pack SOC as measured by torque drops about 10% in 4 hours. I did have my hpcm2 reprogrammed last year as part of the “service high voltage charging system” repair, but I did not notice the range dropping while parked in the summer heat unless it was above 90 degrees. Today’s heat where I am was approximately 65, however it was only about 45 degrees overnight so the battery pack started at around 50 degrees this morning, and ended at 59 degrees. Another weird anomaly that may be part of it is I noticed that the temperature sensors for the power electronics loop temperature readout reads 86 degrees regardless of outside temperature, but sometimes it will show -46 degrees before returning to the original temperature. Could the car possibly be thinking it’s overheating and running the AC to cool itself? I assumed it would use the battery temp sensor but I’m not sure. Any suggestions from anyone else who’s maybe had this happen to them? Any ideas are much appreciated!


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Range loss when parked was a known issue. There was a follow up software update for it. Ask your dealer about PIC6138A. If you never had this update, this would be the problem now. see attached bulletin. It has been so long most folks probably forgot about this one.

PIC6138A.jpg
 
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On my 2013 after it's parked unplugged for three days or so still has full charge, in fact the range keeps going up as it's gone from a city environment to a rural one where the run into town is 36 mph with no stop lights. Waiting to see where it "settles" down.
 
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