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Discussion Starter #1
I have a 2012 Chevy volt with 140,000 miles. It has not had any issues until now. The car will switch to gas mode while there is still plenty of charge remaining in the battery (as much as 80%). The temperature is well above freezing. Stopping, shutting of the car off and restarting resolves the issue. I took it to the dealer. however, the computer was not writing any errors codes.

Any ideas what could be causing this?
 

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If the battery can't sustain the required amps, it could switch to ice
You should have some codes recorded, scan to discover them
 

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make sure to scan all the message but I don't think you would miss the BIG BURN messages.
 

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Discussion Starter #5
I still haven't been able to resolve this issue. Dealership has given up! I have been logging data to see if i can pinpoint what is triggering the engine run. It seems to be temperature dependent but is not consistent. Capture.jpg
https://drive.google.com/open?id=1zM1YQ6f6yvs6eNdB9_oKKJN8IBw1LHNW . the link will take to you the data. No error codes are being reported. I'm not sure i trust the PIDs titles. I would think the battery heater and battery pump would run simultaneously.
Anyone have suggestions on other Pid i should log
 

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Is it switching back and forth or staying in ice like it works with zero EV miles remaining
 

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Discussion Starter #7
typically it will switch back to electric after it burns .07 or .10 gallons of gas. similar to a engine run due to 25 deg ambient temp. However, it works pretty hard to increase the state of charge. You can see this in the third graph in the excel file
 

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Did you drive only in EV mode last few month's? If so, the ICE kick's in just to mix the fuel in the tank, but only if you drive like 4-5 month's only on EV. Just a guess
 

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I would disconnect the 12v battery for 30 minutes and see if that helps.
I wonder if the hood switch could be acting up, or a temp sensor.

Like above, we are assuming it's not trying to burn off the remaining gas in the tank, which is something it will do if you haven't filled up in a long time. This is normal, but it does show a message when it does it.
 

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Discussion Starter #10 (Edited)
Thanks for the input. I'll try the 12v Battery. I will also try bypassing the hood. No messages are displayed when the engine runs.
I wish i could monitor the line of code that is enabling the engine run Temperature.jpg . HV Battery.jpg Battery SOC.jpg
 

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Discussion Starter #11
The engine has been run recently. This happens almost every morning when the temps are in the 30's
 

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Discussion Starter #12
Does anyone know what the battery temperature should be maintained at during cold weather operation?
 

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I have the MyGreenVolt app (free). If the car is off, not plugged in, the battery temp gets very cold. I can't remember exactly, but I believe I have seen the battery at 20 degrees in the past. Given the chance to warm the battery it warms to 50 degrees. I would guess that is the temperature it is happiest at then according to the engineers. I can't remember the top end number, but I know it is at least 70 degrees. I should note, I have a ERDDT defeat switch and have had no problems with the battery being too cold over the past 4 years that I have had the switch installed. Except for my recent temporary, self-correcting glitch you saw on my other post, cold isn't a problem. Eric Belmer (Facebook, over 425k mile Volt), as his battery aged, he gets the message that "Propulsion power reduced" (or something like that) and the engine kicks in to help the battery. We haven't gotten this message, so I don't think we are in the same boat. Different issue. The running of your engine for .03 to .10 gallons is the typical level for warming the engine if it kicks on for any reason. I really like the idea of the hood switch toggling the engine and it stays on to complete the warming cycle, only because there is no error message.
 

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Discussion Starter #14
Thanks, that is what i am seeing also for temps. I'm monitoring the OBD port with Torque pro. Maybe just a coincidence, but i have never seen the issue after the battery reaches 60 degrees. the Battery temp never gets much above 50 when plugged in and remote started. Once i start driving the battery temp gradually increases. (see graphs on previous page). ii would have thought that it would keep heating the battery up to 70 deg when its plugged in and remote started. But it doesn't seem to start heating until i put the car in drive. I left the car unplugged one night and the battery temp started out in the 30's. The engine ran the entire drive even with 70% SOC
 

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I know you probably don't want to hear this Paul but you likely have a bad cell group in your battery. Just one. I had the exact same symptoms and the local Chevy dealer had the car plenty of time and never found the issue. There are no codes. The way I found it is to first buy a VCX Nano and get it running. It runs a Windows XP virtual machine (VM) on your laptop to allow the use of the factory GM GDS 2 software. After I got the GDS 2 working (It took me a while to wrap my brain around how the program was run on the VM), I was able to get in and scan the car's battery control module. When the car was hot off of the charger each of the 96 cell groups was at 4.07V per group, except one. There are 96 groups. The outlier cell group charged to 4.12v. Hmm, I thought. I set the laptop in the passenger floorboard and then drove the car till the battery was depleted. The weather was warm so the car ran on electricity the whole time, about 24 miles if I remember right. SO, at the bottom of charge, the cell groups were distributed around 3.60v with a variance of about .02v. The outlier cell group (number 2) that overcharged at the top end was down around 3.40v and falling fast! I knew then that my problem was that cell group number 2 was B-A-D. I finally had my answer. I took the car back to my local Chevy dealership to see if TAC saw any interest in my situation (I had 174K) but alas, no, they said I was on my own. The fact that the car showed no error codes with an obviously bad cell group I thought would interest them since they had reflashed my brand new Bolt EV for the Same Exact Thing so that it Would trip a code if there was one bad cell group. A safety issue. Hmm.

When I got confirmation that I was being kicked to the curb (I'm not sore), I decided to swap the battery myself. There's a thread stickied in this section about my swap.

I recommend that you get a VCX-Nano setup. If you don't want to do it or can't I can lend my setup to you. I am interested to see if you have the same thing going on. I think you do.
 

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My ‘13 has 134k miles on it and I’ve seen this same behavior a couple times now. My car has spent 99% of its life getting 240v charges, but each time I’ve had the odd motor start when it shouldn’t - was after charging with 110v and not quite being finished charging when unplugged.
It’s almost like their is a glitch in the cars ability to calculate electric miles left. The engine seems to stop and start randomly. I’ve not tried to datalog because there has been no consistency in having the problem. The issue has not re-occurred since the weather got colder.

Have a hunch this may be an early clue that a cell is getting weak and Jiminy may be ahead of the curve on this.
 

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Just get a BT obd reader and monitor min / max / AVG cell voltage, there is a pid for that. Mygreenvolt can monitor it



Bottom right
 

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If the outside air temp is around 40 degrees, it is possible that the engine is running simply to keep the battery pack and electronics at the optimal temperature. I know my '13 volt will run the ICE at temps of 37 or 38 degrees while driving down the highway.

On a side note, I'm having a different issue with my '13 Volt, and don't know nearly enough about the car to troubleshoot. I DO know that after fully charging the car on 240, and plug in my OBD-II gauge before I leave for work, it shows the battery at 86-87%.
When I drive the car, using all the EV before the ICE kicks on, I have driven roughly 35-40 miles on EV, consumed ~11 kWh, yet my gauge shows the battery at 18-22%. Until this past September or October, I was easily able to drive 45-60 miles on EV, and the car never dropped below 33 miles of estimated range in the winter. Now, I can never get the estimated range above 35, and My question is why? I have another thread that I was trying to get help on, without much help, so any help there would be awesome ... but for now, I return you to this thread ... sorry for the near hi-jacking.
 

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If the outside air temp is around 40 degrees, it is possible that the engine is running simply to keep the battery pack and electronics at the optimal temperature. I know my '13 volt will run the ICE at temps of 37 or 38 degrees while driving down the highway.

On a side note, I'm having a different issue with my '13 Volt, and don't know nearly enough about the car to troubleshoot. I DO know that after fully charging the car on 240, and plug in my OBD-II gauge before I leave for work, it shows the battery at 86-87%.
When I drive the car, using all the EV before the ICE kicks on, I have driven roughly 35-40 miles on EV, consumed ~11 kWh, yet my gauge shows the battery at 18-22%. Until this past September or October, I was easily able to drive 45-60 miles on EV, and the car never dropped below 33 miles of estimated range in the winter. Now, I can never get the estimated range above 35, and My question is why? I have another thread that I was trying to get help on, without much help, so any help there would be awesome ... but for now, I return you to this thread ... sorry for the near hi-jacking.
The waste heat from the ICE running is only used to heat the cabin. The lithium battery pack has a dedicated electric battery heater (~2kW.) There is no heater for any of the Volt's electronics as none is required. There is no heating provided for the 12V AGM battery. The battery coolant, engine coolant and electronics coolant are each on an independent liquid (Dex-Cool) cooling loop with no cross feed among the loops. Each cooling loop has its own section of the Volt's radiator. The Voltec transmission also has its own independent core within the Volt's radiator.
 
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