Curious if others have measured battery voltage in a C7? Just checked my volt meter at Batteries Plus and their calibrated Fluke matched my quality VOM exactly, 12.85 volts on a battery on their shelf. Here is my situation. Checked my OCV when there were a few comments about starting issues and it was only 12.4 volts. Put my old charger on and in about 8 hrs of a low amp charge it showed fully charged. Removed it and after 24 hrs still read 12.4 volts. Decided to buy a CTEK 3300 charger (similar if not the same as the Corvette charger) to see if this modern 4 mode charger would be better. Showed full charge after a few hrs so removed and after 24 hrs it still reads ~12.4 volts. Its getting cold so put the CTEK charger on AGM/Cold setting. Showed fully charged quickly and while in maintenance mode shows 12.5 volts. Not sure what type of batter the Delco battery is. It does show a 48P size, and Delco shows an AGM battery with a similar designation. I checked all battery connections and the voltage across terminals to post which showed 0 voltage drop while on a low current draw Iinterior lights on.) If OptimaJim is reading this post, I have a Schumacher charger on my 3 year old Yellow Top Optima and it shows 12.8 volts after charger is removed for 24 hrs. However all batteries appear to be different and the additives, i.e. calcium etc effect the OCV properties.
Note, car is starting fine but driven only a few days a week with the cold weather we’re having even in SC! Called the service manager at the dealer and he says not to worry. Curious. Anybody checked voltage readings with a C7? Any feedback if the C7 Delco is Absorbed Glass Mat (AGM) construction? Emailed Delco-no response.

 

You're overthinking it

12.6 (+/- 10%) volts for a lead acid battery under no load is "fully charged". Your C7 is under load all the time while connected to your car

Relax, you're fine

 

Probably right! When it gets warmer I'll drive more and have less time to overthink! Finally was able to call Delco and get some info. It is not an AGM battery and is model 48PS.
After 3 years the battery in my C6 showed low voltage. I found it had a crack and several cells were low on acid and below the top of the plates! Never knew it had access to the cells. Replaced it with an Optima. Getting the C7 battery out would not be easy so agree, I will wait to see if I have a problem.

 

A 12v car battery should have 6 cells that produce 2.1volts when fully charged, so a fully charged battery would be 12.6 volts. Immediately after charging, the battery can have a surface charge that makes it read above 12.6V, but it should drop quickly to 12.6V when a load is applied.
You could disconnect the cables and check the reading across the terminals as a reference.

Even small voltage drops indicate the battery is not fully charged.
For example:
12.42 = 80%
12.32 = 70%
12.2 = 60%
12.06 = 50%
11.9 = 40%

 

The first thing I'd do is get rid of the OE lead/acid battery; they leak. Buy an Absorbed Glass Mat (AGM) battery and replace it.

 

I agree. First sign of a problem I will. However Optima nor Odyssey show anything for a C7. In fact the Optima sight doesn't even show sizes for 2014 models. Sears indicates no product either. Have to believe there is one as this battery was used for a number of years, a Delco 48PS.
I'll keep on looking as I want to be ready and won't bother with a warrantee for this one. One problem when I park at the airport for a week will cost more time and money than a new battery!

 

I have a 2 week trip coming up where my car will sit in covered off airport parking. I will take a 10mm socket with me and disconnect the neg side of the batt and lock the car. When I come home I will manually open it up with key and reconnect the batt cable. Nothing in the settings will be lost. This is much healthier for the batt than letting it cycle (discharge and recharge).

 

That is one way to do it, but I left my C6 for over 2 weeks a number of times while we were on trips and never had a starting problem. When checking the voltage when it was 3 years old, it was slightly low. Found out the acid in two cells was below the plates! There was a small crack in the case! Bought an Optima to replace it and it was prefect for 3 more years.

 

My C6 is a 2007 and still going on the original battery... Knock on wood...