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Discussion Starter · #1 ·
Today while driving along with a mostly full battery on my 2012 Volt I suddenly got a message on the screen that said "Service Battery Charging System". Then the red 12V battery light went up on the display and stayed there. I pulled over and immediately read stuff from this forum with many different results. We had planned a big trip today but instead I turned around and drove the short drive home without ever turning the car off.

It was Saturday evening so no dealer open today or tomorrow. The car still takes a charge and I plugged it in and charged it full hoping that maybe when I restarted it the message and light would be gone but no Christmas miracle! I have 83,000 km electric and 123,000 km overall with the original 12V battery still. My questions are do people think it is safe for me to drive the 9 km to the dealer on Monday morning or should I get a tow? Also any chance this will be covered under Voltec 8 year warranty? Is it likely I will need to get a new 12V battery or is it a fuse or any ideas as most of the references I could see on past threads said the car wouldn't charge anymore (which mine does) and that the whole system shut down after a few minutes but after the light first went on I parked with the car on for 5 minutes and then also drove 5 minutes home. Tried calling OnStar but mine has expired so no help there. Any info would be much appreciated, thanks!
 

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This is a very common, search the forum for "service high voltage charging system", or "SHVCS".

It's not a safety issue, the worst that can happen is that your charging system is disabled but the car is perfectly safe to drive otherwise.

If your car doesn't have the battery coolant bottle upgrade already in place, providing your vehicle is still covered under the 8YR/1000M Voltec warranty, they should do it for free.

Then buy the override kit in my signature for an easy and inexpensive way to prevent this from happening again.
 

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Post a picture of your battery coolant tank's fluid level.
 

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The OP said this was 'Service Battery Charging System', this is the 12 volt system, not the HV battery.
To the OP, it sounds like your APM, (accessory power module) has failed, or at least can't provide enough power to the 12 volt systems. I don't think that I would try to drive it to the dealer with the 12 volt systems depending on the 12 volt battery instead of the APM. One thing you could try, is to start your car then remove the negative battery connection. If the car dies right away you will know that the APM has failed. If it continues to run you may have a shorted 12 volt battery that needs replacing. If the battery is 5 years old, it probably should be replaced anyway.
 

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Discussion Starter · #5 ·
TSquare, thanks, you're right, it was not the "Service High Voltage Charging System" problem which I also have had in the past but "Service Battery Charging System" for the 12 V system. You don't recommend driving it to the dealer, what about 1 km to the closest big empty parking lot? I've been told it's always best to have a flatbed tow the Volt and unfortunately right now my car is in my garage on a busy street with a steep driveway incline. Would the risk of driving it just be the safety of it shutting down or could it also damage other parts?

Also if you think it is the APM any idea on what the price range for that would be and would it be under the Voltec warranty of 8 years as my car is over 6 years old now? Thanks again.
 

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Would the risk of driving it just be the safety of it shutting down or could it also damage other parts?


Buying the cheapest lithium-ion jump starter you could find like pictured above since CCA means nothing to the Volt is more than enough capacity in order to get the Gen1 turned ON in lieu of a dead 12V AGM or even a missing/disconnected AGM for that matter.

There is no risk of damage from lack of 12V DC provided by the AGM to the Volt.
When I drove my Gen1 around with the 12V AGM disconnected the Volt behaved just like normal and threw out absolutely no CEL/DTCs!;)
 

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TSquare, thanks, you're right, it was not the "Service High Voltage Charging System" problem which I also have had in the past but "Service Battery Charging System" for the 12 V system.
Sorry, for some reason my mind went straight to the SHVCS issue.

If everything is behaving as normal in the car still, It's still safe to drive - yes, the 12V battery may not be getting charged, but as long as there's still a base level of charge in it, the car should still be fine to drive such a short distance. I would however minimize 12V loads, so turn *everything* inside the car off (HVAC fan is a big draw, as is other 12v loads like seat heaters etc) and drive during the daylight hours so exterior lighting isn't needed either. With very little load even a 12v battery that isn't being charged anymore is going to be fine for that period of time.

But, if you're concerned (I live not far away and I know it's bloody frigid out today, so that can reduce battery capacity, especially one that might be partially discharged, and not being actively charged), or it's showing signs of actually being depleted, I agree with the earlier suggestion - get a 12V booster box of some sort (I see you're in Canada, Canadian Tire sells lots of different options, but as was mentioned, you do NOT need a lot of capacity so buy the cheapest one you can), make sure it's charged to 100%, pop the little battery access hatches under the rear cover, and connect the box to the 12V battery under there.

Turn it on, and you're good to go - the booster will be MORE than enough to keep everything working perfectly normal for such a short drive.
 

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I looked at a few Lithium-Ion Jump starters. If you simply want one, then go for it, otherwise if you spend $50 or even $100 on one of these just for one 9 km drive to the dealer then it your be by far cheaper to get a tow, and also less wasteful. Honestly, how often do you plan to jump start your battery in the next 10 years? At that point the lithium ion battery inside the device will be likely weak, if not at very poor health.
 

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TSquare, thanks, you're right, it was not the "Service High Voltage Charging System" problem which I also have had in the past but "Service Battery Charging System" for the 12 V system. You don't recommend driving it to the dealer, what about 1 km to the closest big empty parking lot? I've been told it's always best to have a flatbed tow the Volt and unfortunately right now my car is in my garage on a busy street with a steep driveway incline. Would the risk of driving it just be the safety of it shutting down or could it also damage other parts?

Also if you think it is the APM any idea on what the price range for that would be and would it be under the Voltec warranty of 8 years as my car is over 6 years old now? Thanks again.
If your APM is dead, and the 12 volt battery still charges while plugged in, you will be able to drive it a short distance. Think of it like a normal ICE car with a dead alternator. How far can you drive just on the 12 volt battery. If your dealer is less that 5 miles away and the 12 volt battery is fully charged, you can probably make it. Turn off every thing that you can inside the car.
You would have to check with the dealer, but I believe the APM is covered by the Voltec Warranty.
 

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The Accessory DC Power Control Module (APM) is the only module that charges the 12 volt battery. I have replaced many 12 volt batteries but never an APM. The APM may set a DTC if the 12 volt battery voltage dose not increase voltage fast enough when being charge.
If your 12 volt battery is the original , I recommend ask the dealer to replace the battery, Don't pay to have a old battery tested, But also ask them to check for DTCs and freeze frame before 12 volt battery is disconnected and clear all DTCs with new battery installed ( may need to pay for this).

FYI the scan tool use to check DTCs and other scantool test is call GDS-2. The GDS-2 automatically records this data on the PC or laptop being used and can be reviewed/printed later

By asking them to check DTCs and freeze before hand is if addition diagnostic may be needed. The volt usually will set more than 40 DTCs when the 12 volt battery is discharged or disconnected
 

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The Accessory DC Power Control Module (APM) is the only module that charges the 12 volt battery.
Not to sound like a broken record but I thought this had been settled over in that other thread: PROPULSION POWER REDUCED message that the Lear 3.3kW High Voltage Charger aka HV Charger aka OBCM provides a trickle charge to the 12V AGM on the Gen1s while the Volt is actively charging (green charging light on the dash)?:confused:

If the OBCM were defective and not providing 12V DC during charging, this charging cycle load would cause the 12V AGM to be flat or very close to it after a long charging cycle: 2011 Volt - 12V battery drains while plugged in and charging

Of course this behavior has now changed under the Gen2 where the HV charger no longer provides 12V DC during charging instead it is now done using the APM: http://gm-volt.com/forum/showthread.php?5409-Auxillary-Battery&p=3346034#post3346034
 

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Don't worry about sounding like a broken record because I just joined this forum so I missed the earlier stuff. But as far as the T 18 battery charger also charges the 12 volt battery, you are correct this is true. So I learn something new today.
 

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Discussion Starter · #15 ·
Thanks for all the responses. So to update my original post, yesterday I got a flat bed tow to the dealer. Today they called and said it was the APM Part #24262768. They are saying that it is not covered under the Voltec warranty. I called GM to complain about that, am I correct in thinking that an APM should be covered because the high voltage battery is involved with it. If the HV battery goes through the APM to charge the 12V battery then wouldn't an APM like this be unique to a plug in car? On a normal car isn't there a direct link to the 12V battery? I'm not very technical so could be off on this, is it legit to think this should be covered under Voltec?

They are quoting $655 Canadian for the part and 3 hours of labour for diagnosis, installation and recalibration. Does that sound reasonable as to a layman it seems like that would be a much quicker job than that? Any input would be appreciated, thanks a lot.
 

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Thanks for all the responses. So to update my original post, yesterday I got a flat bed tow to the dealer. Today they called and said it was the APM Part #24262768. They are saying that it is not covered under the Voltec warranty. I called GM to complain about that, am I correct in thinking that an APM should be covered because the high voltage battery is involved with it. If the HV battery goes through the APM to charge the 12V battery then wouldn't an APM like this be unique to a plug in car? On a normal car isn't there a direct link to the 12V battery? I'm not very technical so could be off on this, is it legit to think this should be covered under Voltec?

They are quoting $655 Canadian for the part and 3 hours of labour for diagnosis, installation and recalibration. Does that sound reasonable as to a layman it seems like that would be a much quicker job than that? Any input would be appreciated, thanks a lot.




Would assume 14V APM should be covered under warranty using the GLC 5010220 referenced above!?:confused:
 

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Discussion Starter · #17 ·
Wow, thanks, I didn't get to talk to a Volt advisor directly but they opened a case for me and are supposed to get back to me tomorrow, then I found a reference to the APM being covered in a pdf of a 2013 manual, but I can't find my warranty pamphlet for the 2012 model. However, with that info and now this post I should definitely be able to get it covered, plus they should be impressed I can even quote them the labour code! Thanks again.
 
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