23/C8Z

W T H

AORoads

^^^ I'm with him! The TRANS????

xxmr210xx

Read over this post
https://www.corvetteforum.com/forums...post1607148931

FlyinLow

Bad cells in battery cause all kinds of weird issues. As I mentioned before, had one go bad in our pickup this summer. Put my big Craftsmen charger on it and it showed charge within a half hour, and the vehicle started fine. Two hours later the battery was completely dead. Put the charger back on it and again it charged full in a half hour, started the vehicle, drove it on some errands, everything was fine. Parked it in the garage and two hours later it was dead. Replaced the battery and have had no issues since. Likely your tender is fine, not sure how the dealer can check to see if its working properly.

jetjoc4809

I have a 2023 ZO6 convertible, one of the earliest deliveries in December 2022. From the day I took delivery in Florida I have had continuous battery issues. With less than 50 miles on the vehicle I delivered it to a high end detail shop to have it ceramic coated and bras installed. We left on a trip overseas over the holidays and did not return for almost three weeks. Upon my arrival at the shop I discovered the battery was absolutely dead, so dead that the door would not open without the emergency key. It goes without saying that the engine would not turn over, so the shop put a booster on the battery and was able to start it. After going through the drill of cycling windows and resetting preferences I took a long enough drive to verify that the battery recharged, and the only remaining issue was the engine light stayed on. However, that cured itself within a couple of days so I cancelled my appointment at the dealer and chalked it up to a battery below full charge at delivery and a ball dropped by the detail shop in not running the engine.
Wishful thinking! After a couple more episodes like this in my garage where the battery was so dead I was unable to open the door. Neither could I gain access to the battery without the emergency mechanical cable. I finally decided to leave the car with my Corvette mechanic at my dealership, a guy who races Vettes and did great work sorting out issues on my C7 ZO6. Mind you, on each occasion my battery went dead in less than two weeks. While I did not have my Corvette battery charger connected, on those occasions when I did the charger never reached green - a full charge, and became quite hot to the touch.
My mechanic, after a couple of days of diagnosis, concluded that the battery was in excellent shape; it tested 97% after several charge recharge cycles. So there had to be a system issue causing this problem. Corroborating that theory he found that database updates were inoperative. It took over 6 gigabytes of data to bring it up to date. So he asked me to drive the car for 30 days or so to see if the problem was solved by the updates. But over the next two months, after two more replays of this debacle, I made another appointment to bring the car in for evaluation by the Chevrolet Engineering team to sort this out once and for all. They kept the car for two weeks doing remote satellite diagnosis with the engineering team. My mechanic became frustrated with the slow pace of progress and confided in me that the radio module was found to be defective fairly early on (the unit that receives transmissions for software updates), but it took two weeks of continuous testing before the team finally authorized a part replacement. Although my mechanic had diagnosed that same issue months before, he was unable to order the part on warranty without factory approval.
After replacement of the module my mechanic ran a test on battery draw. For an unattended parked vehicle I was told that the residual draw on the battery should not exceed 10 milliamps - yet mine was over 100 milliamps! To make a long story a bit shorter, after two more weeks of testing each system (each has its own module that acts as a circuit breaker) my mechanic finally was able to isolate the culprit. I know this will sound ridiculous but It turned out that the passenger seat lumbar support actuator was the culprit. After disconnecting and disabling it the draw dropped to 9 milliamps. A new actuator was ordered but was supply constrained for three weeks. Who cared?
I now have driven the car for nearly two months and everything seems to work perfectly. The battery remains fully charged without a charger and software updates are automatically completed. I realize I might have gone on for too long in my story, but the bottom line for those of you having battery drain issues is that the problem had nothing to do with my battery. My mechanic said that the factory engineers revealed to him that the C8 ZO6 has 600 modules! So the statistical probability of a module failure is much higher than you might think. Check your current draw right away if you are experiencing battery failures. And even if you find excessive current draw don't think you're out of the woods. The modules you need to access to disable electronic circuits are quite inaccessible - requiring removal of the battery in the frunk for the systems in the front of the car and removal of the vertical stainless steel trim between the seats to access the rear system controls- not a do it yourselfer job!
Hope this is helpful for those who find themselves in similar situations.

joeking

I bet your maintainer is still good.

gnt

This thread screams, buy an extended warranty.

Exactly what I’ll be doing!

Didier9

The battery tender does not check for the battery's internal resistance. It is a low current device. When you start the car, the current draw (even before you start the engine) is greater (for a short time) than what the battery tender provides. The car's computer will notice the voltage drop before the battery tender does.
When a new battery goes bad, it's usually a bad connection between elements inside the battery. Like all bad connections, it is usually intermittent and can change depending on temperature, mechanical shock and the actual current you are trying to get in or out of the battery.

Didier9

I got the extended service contract on both cars for just this reason. It removes the "need approval from GM for warranty repair" from the equation.
I rarely take extended service contracts on cars, but it's been a while since I bought a new car and the cost and complexity of electronics in modern cars is getting a bit out of hand.
So far, before the Corvettes, I had it on three (used) cars and it did pay off on two! (a '1991 Maxima with a bad torque converter and a '2013 Infiniti FX37 with a bad transmission valve body). In both cases, the repair cost was the same or higher than what I paid for the service contract. The 3rd one was an '05 Altima V6 and if I had paid attention to the noise when it started, it would have paid for the timing chain tensioner. Instead, I waited until the service contract had expired...

LIE2ME

Had a similar problem on my wife's 2019 Equinox. Good news, it was just the battery; bad news, we were charged a $350.00 "Diagnosis Fee" for the mechanic to figure out it was the $150.00 battery. Total charges were over $500.00.....

TensionED

Thanks Angus (ha ha). Though do you have to use the clamps attached to the battery or would it also work plugging into the 12v outlet in the frunk?