As the title says I went to start my 23 and got multiple error codes and it would not start. I drove the C8 about 120 miles 4 days ago. I plugged in the Corvette battery tender after the failure to start and it was on the first light which indicates a low battery. So after 2 hours the battery tender is on the second light.

If the car is going to sit for a week or more due to weather I always put it on the battery tender... I think I've done that 5-6 times so far in the two years I've owned it. It has 33k miles so I drive it a lot.

What would cause the battery to go flat that fast?

JT

 

Only a guess but if there is a glitch and some part of the active circuit does not shut down that would drain the battery. I have had a few cars where this was always the case and battery tenders were pretty much required (I am looking at you Lotus).

 

Your battery tender is not designed to charge a depleted battery; they are designed to "maintain" a healthy battery. Get yourself a cheap code reader to see what the error codes are

 

You may have a defective battery.
I say that because my other car had the same problem. I went out to start and it was completely dead. I recharged it and it seemed fine for 2 weeks but then did it again. I changed the battery and all is well now.

 

Or a failed GM OTA update.

 

Very Good Point!!

 

Replaced my battery after 3 years

 

So this morning the tender is at 3/4 charge. If some device failed to go to sleep that would explain it. Before I drive it I'll make sure my jumper battery is fully charged now. The tender won't charge a fully dead battery but it will charge one that still has 2v. Oddly my backhoe battery was also dead yesterday...

JT

 

I just experienced a defective battery in my two-year-old Cadillac CT5-V Blackwing. I had a minor health issue and couldn’t drive it for 12 days. When I finally went to start it, the car was completely dead. I had to remove the blade from the key fob and pop off the door handle cover to access the mechanical lock so I could get into the car and open the hood.

As 449er mentioned—and as I quickly learned—battery tenders aren’t designed to charge a completely dead battery. Mine was only showing 6 volts. I ended up buying a NOCO Genius10 (10 Amp charger), which was able to put enough juice in the battery to get the car started. I drove it to the dealer, who diagnosed a bad cell. Fortunately, I got a new battery installed under warranty.

Bottom line: OEM batteries can go bad well before you’d expect.

 

The dealer can check for parasitic draw. Normal parasitic draw after the car has been off for 10-15 minutes undisturbed is about 10 ma so thats very very low.

Yes your Corvette CTEK tender is a 4.5 amp charger and it can charge the battery, if it sees at least 2V (not typo, not 12) but it will take longer than a 10 amp charger. This statement is supported by what is in the CTEK manual.

Based on the manual that comes with the CTEK, it needs to see at least 2V to initiate charging. It says that "if the charger isn't connected to the battery within 2 minutes [of being plugged in to the wall] or if the battery voltage is below 2V it will enter the energy save mode and show a flashing light. The manual indicates "time to charge a battery from empty to 80% state of charge" for a 110AH battery is 26 hours. So, if it starts to charge, and if the battery is good, it will indeed charge it up, but slower than a 10 amp charger. The manual does not indicate what "empty" means - I don't think it means 0% state of charge though - as it needs to see that minimum voltage. In the event that you get an error light on the charger (the manual calls it a charger), there are instructions for waking up a battery. It says "Press and hold RESET button for 10 seconds for manual battery wake up. If the charger doesn't continue, this procedure can be repeated up to 5 times. If this still doesn't work, do not restart the charger, the battery may need to be replaced."

 

The OTA updates always ask you first...

JT

 

@Andybump Thanks so much for the info, you always have the best information. I knew that the maintainer/charger needed to see some voltage but was not sure how much. I'm quite surprised it's only 2v. On my backhoe yesterday it was totally flat so I connected up my old school 10 amp charger to it for an hour then plugged my big charger/maintainer in to finish up the charge.

So the car started quite normally this morning and after idling a bit the CETK showed green full battery. I plugged the CETK back in and it jumped to 1/2 full so I'll leave it on until I can go to the dealer and have them check for parasitic draw or defective battery. And in the mean time I'm making sure my NOCO GBX75 is fully charged before I make the trip to the dealer.

Edit: within a few minutes the charger indicated 80% at least I think the third light means that.

JT

 

‘not always as I recall.

 

It asked me for permission to do the update. I've only got one OTA update since I bought the car. The only other update was done at the dealer. It's not like it's going to an update while you're driving the car... maybe if it was WindBlows based it might...

JT

 

Its not supposed to do an OTA update without permission each time. I once got a message telling me an update failed to install even though I never received a notice and never gave permission. I do not know what type of update it was. Apparently now, besides the OTA for the vehicle software, there are also updates to apps.

 

The CTEK finally shows full charge, I'm going to leave it on over night until I go to the dealer tomorrow. So it's been charging for about 24 hours.

JT

 

So far they said communication error with the body control module.
They gave me loner and have been working on it for 3 hours now.

JT

 

Just talked to the service gal and she said it takes all night to run all the tests on the control modules... not looking like a battery issue now.

JT

 

Could still be battery. I've had 2 batteries fully die on me (2 different c8s, what luck) and both times the electronics freaked out and tossed a pile of lost communication codes. These things can get very unhappy with a low/dead battery.

Hope it's an easy one for you!

 

GM has issued several security updates for various Global-B vehicles including the C8 in the past 6 months. These are complex updates involving encryption and key exchange/signing among various vehicle modules, so a few problems are not unusual. A couple of weeks ago, a new TSB was also issued for: "Identifying Non-GM (Aftermarket) Engine Calibrations”

As in some previous cases with C8’s, they will get resolved……especially if GM Engineering is involved…….nothing to worry about.