[tentcamper]

But getting back to the original question, it depends on the temperature of the battery. I use as a rule of thumb 12.7/12.8 after it's been sitting for 24 hours.

But it depends on the temp.

Several years ago I did some reading. Only because my battery on the camper stored outside would not hold the voltage I was expecting in very cold weather. If interested i'm sure there is a chart you can google. Ideal fully charged voltage most mentioned for a lead acid battery is at 68 degrees 24 hours after charge. Ideal voltages above or below 68 degrees will be difference. Also the highest available amps was at 68 degrees.

Back when I looked at it 12.2/12.3 was a good voltage at 0-F. What I read back then, indicated that colder temps, in the sub zero range was the best for battery storage, but you need a good charger that would adjust to the temps. But if you did it right and stored the battery in a deep freeze you could get 2-4x the life. But at those temp you have a decrease in available amps.

One of my reading back then, talked about chargers and that most did not compensate for temps, and that was the main cause for early life battery failure in the very cold and hot areas.