I have a 2021 C8, Z51, Convertible. I did not buy the optional battery tender charger offered by Chevrolet. I have been using a 4-Bank Deltran Battery Tender that works fine for all my other cars. I will be leaving the car for a month and want to keep the battery charged, so did some testing in advance. Plugging in the Deltran cigarette lighter adapter to the C8 12-Volt Port in the trunk, then to the Deltran Battery Tender quick-disconnect, and the yellow light is supposed to stop blinking and go on "hard" yellow to show connectivity. Then as the battery charges the lights advance toward "hard" green, indicating full charge achieved/maintained. But nothing happens and the yellow LED just flashes as if nothing is connected. I tried all (4) ports of the Deltran unit and also checked them on another car that connects with the traditional battery terminal clips. All good on the other cars. The Deltran cable adapter going to the 12-Volt port has a red LED indicator showing 12 volts present when plugged into the C8 Port. Additionally I checked the connector on the Deltran cable with a multimeter. About 13 volts. I tested the circuit in the C8 using my friends brand new C8 Battery Tender he bought with his car. This is a "plug and play" that you connect it and it shows hard connect light, then shows 80% charge and finally full charge. That works fine on my car with the LEDs lighting up sequentially. I talked to someone at Deltran who assured me my Deltran Battery Tender will work with the C8. Anybody have any info on this?....besides the obvious "buy The Chevrolet Charger".......

 

Battery tender is crap, it will smoke, all mine have Nothing beats a real battery like an Oddesy. Who is the manufacturer of your current battery?

 

You have very bad luck or buy crappy tenders. In case it’s the latter, try a Schauer or Noco. They are very nice. I have them them both, but I like the Schauer better. Never had an issue with one.

 

Have you tried connecting directly to the battery posts using the clamp connectors? Maybe, the 12V plug on your charger may not be making proper contact through the 12V socket in the C8.

 

I've used Battery Tenders on cars and motorcycles for 30 years. I've had one failure in all that time. Maybe the problem is you?

 

The bottom of your Deltrans describes it as 12V / 1.25 Amp. The one that is sold through Chevrolet Accessories is labeled at 4.3 Amps. Perhaps the Deltrans is too weak to charge the C8 battery?

Chevrolet Corvette C8 Charger by CTEK

 

Where’s the OP?