Since I am seeing more and more issues that seem to stem from a low voltage condition of the 12 volt battery and it is replaced (or will be) I thought I would establish this tracking thread. I have stood on the sidelines (via other forums) and watched as several other EV's went through the teething issue of having either a faulty 12 volt battery, or a more complicated issue of a poor recharging protocol, or perhaps even a faulty component that impacted 12 volt recharging. If you have had your's replaced, or in the future need a replacement 12 volt battery please share that experience here and be sure to include how your tech. wrote up the problem and what was done to remedy it.It will be interesting to see what we discover.
Had issues and your 12 volt battery was replaced?
Chip
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Tizan, I replied the same day "So is the date ON the tire info tag the build date? Maybe their label machine ran out of paper. I'll look again tomorrow."
Sorry, this is a dupe (it's accurate but it's a dupe resulting from my clumsiness using the forum). Just had the "Battery Fault" message again and had it towed to the dealer. Dead in water in the garage and won't start, won't shift, etc. The 12V was replaced 11/27/24. I'm getting very nervous that it will happen again - but somewhere on the road. Brrr.....
Had my second "Battery Fault" this morning - car's being towed to dealer.interesting you are the second person here mentioning that your car has no manufacture date on.
here is the other one. I wonder if you got replicas(like fake Rolex assembled in Hong Kong)
Car's already in the shop. When I get it back maybe I can check the update history and tell what the version was when I had the failure.
I got my car back this morning. They kept it an extra day because they did a reset and wanted to wait longer than 30 minutes to be real sure it worked.
No new battery - the one that failed was replaced last November when I had my first 12V brick experience.
It doesn't seem to me that much was done. What does "Sent DTCS data to TAC..." mean? I looked up "serial data authentication" and it appears to be a process to see if there are any bogus parts in the system. I guess I look suspicious.
Here's a pic of the service ticket - maybe it will help anyone following this issue.
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Here's what the app shows for update history - nothing new since last Oct, a month prior to the first brick. I did a "check for updates" but the only thing added was the "last checked" line dated today.
I can't seem to determine the software level - the closest thing I see to "Software" in Settings is information about Android, all dated in 2023. Do the "Update" numbers reveal the level?
The dealer folks are polite and friendly, but I'm not sure they have a grasp of whatever the issue is. Hope I don't have a third.
No new battery - the one that failed was replaced last November when I had my first 12V brick experience.
It doesn't seem to me that much was done. What does "Sent DTCS data to TAC..." mean? I looked up "serial data authentication" and it appears to be a process to see if there are any bogus parts in the system. I guess I look suspicious.
Here's a pic of the service ticket - maybe it will help anyone following this issue.
Here's what the app shows for update history - nothing new since last Oct, a month prior to the first brick. I did a "check for updates" but the only thing added was the "last checked" line dated today.
I can't seem to determine the software level - the closest thing I see to "Software" in Settings is information about Android, all dated in 2023. Do the "Update" numbers reveal the level?
The dealer folks are polite and friendly, but I'm not sure they have a grasp of whatever the issue is. Hope I don't have a third.
Attachments
I hate to alarm you, but a repeated condition where the 12V. battery is allowed to get into a low voltage SOC (state of charge) below 12 V. will do damage to that battery. When your car has been in a bricked condition did the dealer inform you as to what the indicated voltage of that battery was? I see they recharged it, but you probably will need to keep an eye on it's SOC. It will be a good idea to get a multimeter if you don't own one already and check the 12 volt battery to make sure it is not losing its charge or not being recharged by the 12 V. recharging system in the car. If you see that it is not, or that your seeing a less than 12 volt SOC you need to contact your dealer again.
Thank you, Chip.
For the first failure last December, it was on the ticket - "...the battery had a bad cell with volts of 8V," but there was no such info on the recent ticket.
I wrote my service rep and asked him if he could find out what it was. I also asked him if a battery tender or multiple owner trips under the shroud to get to the 12V would affect my warranty.
Seems to me GM ought to offer free tender installs to owners so that they wouldn't brick the first time!
Thanks again, Stay tuned.
For the first failure last December, it was on the ticket - "...the battery had a bad cell with volts of 8V," but there was no such info on the recent ticket.
I wrote my service rep and asked him if he could find out what it was. I also asked him if a battery tender or multiple owner trips under the shroud to get to the 12V would affect my warranty.
Seems to me GM ought to offer free tender installs to owners so that they wouldn't brick the first time!
Thanks again, Stay tuned.
TW; It occurs to me that you should be able to remove the plastic shroud and leave it off while you get a voltage profile on your battery. After all the 2025's don't have a shroud on them at all. (based on what I understand)
I imagine GM wishes the 2024's didn't have one either.
I'm sure I CAN take it off - I'm just paranoid about honking up my warranty.
I'll let you know if I get any info from the service tech.
I removed mine a few weeks ago. It was more complicated than I had expected from reading the instructions so I'm glad I did it. I would have hated to try to get access to the 12V battery when/if I NEEDED to. One of the plastic fasteners went flying and I didn't find it... I have the (surprisingly many) pieces stored in the garage attic.
I wonder if 12V issues are related to the vehicle waking up when the key is near. I move around near my garage frequently and the car is always responding to the key in my pocket. That can't be good for the 12V battery. I meant to put a Bluetooth monitor on the battery but other things keep coming up.
That should not make a difference because the car periodically tops off the 12 volt battery from an internal charger that runs off the traction battery. I suspect GM got a batch of 12 volt batteries with a high failure rate.
On some EVs, this 12V recharge only happens when the ignition is on, which activates the DC-DC converter. Not sure if that's how it works for the Blazer EV though.
If look at the manual about long term storage...you get the idea that when the car is not plugged in...it wakes up once a day at least to top up the 12V till the HV battery goes below 30%. Then the 12V is on its own till it dies ...there is a lot of modules drawing current including taking to your fob or your phone app etc. When plugged in it may top up the 12V more often and it might even cool the HV battery when awake when ambient temp is 90F and above.
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Are consumers paying for the replacement of the 12 volt batteries?
I didn't have to pay for the one they replaced last November.
I found the tag with my build date! It's way down at the bottom of the post and facing outward, not forward like the tire information. Mine was built 01/24. I didn't take delivery until May - so it had plenty of time to deteriorate. Not sure if it's important, but the tag has a model date: 571MD26
Wish me luck - putting a monitor on today - or trying to, at least. It's an LNEX BVM02 - thirty bucks at Amazon.
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