"The typical charging voltage is between 2.15 volts per cell (12.9 volts for a 12V 6 cell battery) and 2.35 volts per cell (14.1 volts
for a 12V 6 cell battery). These voltages are appropriate to apply to a fully charged battery without overcharging or damage."
"All Lead acid batteries (Gel, AGM, Flooded, Drycell, etc) are made up of a series of 2.2 volt cells that are bridged together in series to reach their final desired voltage. For instance, a 6 volt battery will have 3 cells (3 x2.2= 6.6 volts), a 12 volt battery will have 6 cells (6 x2.2=13.2 volts) and so on.That 2.2 volts is the fully charged, straight off the charger number. The actual resting voltage, or the voltage a battery will settle at 12-24 hours after being removed from the charger, is closer to 2.1 volts per cell, or about 6.4 volts for a 6v battery, and 12.7 volts
for a 12v battery. These numbers assume 100% healthy cells, and may vary a bit lower for older batteries."
I was getting 12.46 v after more 10 hours without charging or at rest. I do not know if that difference from 12.7 v means the battery is bad.
Answering my own question: "It's a good place to start, though. This is called the “open cell” or “resting” voltage of the battery. Resting fully charged 12 volt batteries are around 12.8-12.9 volts, and flat dead ones are at 12.0 volts, so 12.4 volts on a resting battery means it's about 50% charged." So my small battery has just 50% of charge!