After a new battery and charger I've been monitoring battery drain, possibly a bit obsessively.
So far it seems as if the battery looses 0.2v per 24 hours, or 1.2v a week.
The battery needs to be at 12.2v, minimum, to be certain of starting the engine, so 10 days is about the longest time it is "safe" to leave the car without charging, or using.
It is, of course, possible to turn everything off with the master switch, but then the radio station memory is lost.
What I want to know is what is drawing power?
Difficult to comment sensibly without some more details - battery size for example. Does the car have an alarm? Does it have a tracker? Those two are the most likely permanent draws on the battery. You might expect an alarm to use maybe 40mA and a tracker a further 20 so 60 in total. Over 24 hours thats 1.5 Ah. If your battery is fully charged and is say 60Ah capacity then it will drop to 12.2 v ( half charged) in something like 20 days.
Your numbers are a bit odd. Fully charged your battery voltage is 12.7 or 12.8. 10 days to drop to 12.2 is 0.06 per day. 0.2v per day would have your battery down to 10.7v in 10 days. Are you being confused by the approc 14v voltage you can measure immediately after running the engine? This is surface charge and there is no power behind it - left to itself it will decay away failry quickly. to the normal 12.7.
On a modern "electronic " car, a stand time before you get issues of 15 to 20 days isnt unusual. Both my Ferraris have been in that bracket as is my wife's Smart Roadster
