Left the car yesterday on my parking. Clicked on YES for the automatic update.
Today, car won’t start, looks like battery is dead.

anybody had the same issue before?

 

Did you have the battery on a trickle charger any time within a day or two prior to the update?

 

An "Advanced search" here will locate a number of similar reports, but I don't recall one for a while. Best of luck with it.

 

nope.
car was just outside.

 

If it’s business as usual for GM, then no worries.
they’ll send me a person to recharge the battery.

i will try in another hour then call their support/ customer care

 

Yeah happened to me. The car is not bricked - just a dead battery. Jump it (you need to let the battery charge a bit, or else won’t turn over - maybe 20 minutes). It will start up. Let the battery charge for a day with a trickle charger (or drive it for an hour or whatever). In my my case, the BCM was jacked - front and rear camera issues. Had to pull off the battery leads and let it sit for 20 minutes - reconnected and started and the camera issues were fixed.

next day, it said the same software update was available. This time I babysat it and it worked fine. Car is all good now.

 

The point I was trying to make is if it hadn’t been on a trickle charger in a while the battery could have been low.

 

the update won’t start unless the battery has 70% charge.

 

Hopefully it just the battery. My car was bricked in June of 2021 and was out of commission for two weeks when a module was fried by the update. About 5 others C8 owners on this forum had similar bricking. Good luck with your issue.

 

Good luck, sure hope it is only the battery that needs to be fully charged.

 

Does this have anything to do with how often the car is driven? IE battery is getting low due to not being driven regularly.

 

It is a known issue with software these updates that they sometimes kill the battery. You will get a massage that conditions aren't right for an update if the battery is too low to start the update. For many the first sign that an update is pending is the radio stays on when they open the door to leave the car. Someone had posted they had measured the current draw immediately after the car was shut off and I think it was around 10 amps. An update that has gone bad probably gets stuck in a loop keeping the system alive until the battery goes dead or maybe neglects to shut the system down after the update. The C8 has a 70 amp hour battery so if the car is drawing 10 amps a fully charged battery will go dead in 7 hours, and get too low to start the car a lot sooner than that. And having a battery maintainer connected during a bad update isn't going to help much, most do not put out enough current to keep the battery alive but may make it take a little longer before it goes dead.

The best thing you can do to prevent a dead battery due to a failed update is check the car after half an hour or so to make sure everything went right. If the car doesn't come alive or won't start then disconnect the battery and reconnect it. Leaving the drivers window down and the frunk lid resting on the latch will make access easier if the battery is killed or the system is dead.

 

I suggest to not have auto-update on. Just do them when you are at the dealer for something else. None of these updates are going to make your car much different than it was before the update while still risking ending up with a brick.

 

There isn't an auto update option, just an option to automatically download the updates. The car will never do an update without first asking for your permission.

 

My experience, often having stored cars, is that once a battery goes completely dead/flat, it'll never be the same after re-charge. A complete discharge irreversibly damages a lead acid battery. I read that a new battery, completely discharged, irrevocably looses 30% of its capacity. Just my experience. Nickel Cadmium batteries; as used in satellites, aren't harmed by a complete discharge if done slowly. I don't know anything about lithium batteries.

From what I've read, I'd leave the battery maintainer on when doing an update. The OEM battery maintainer is apparently a basic CTEK model. Their more expensive models do have a special cycle for helping to rejuvenate a completely discharged lead acid battery. It's a pulsed voltage wave train that supposedly removes a destructive sulfate layer that forms in the battery when completely discharged. I don' t know what "sulfate layer" really means.

 

Thank you for the explanation. So, you are saying that typically a successful update takes about a 1/2 hour or less?

 

Most updates seem to take 10 minutes or less.

When these updates fail and kill the battery, they appear to drain it far faster than a float charger can keep up with.

 

Yes, however there have been posts stating that the update said it could take up to an hour.

 

My last 2 updates took about 5 min....

 

That's a good thing it does not take that long. I plan to baby sit it until it's done. I am neither patient enough or smart enough to get back into this thing if it bricks.