johnlvs2run

Update:
Results of connecting the battery cables for 24 hours.
12.72 volts - beginning
12.64 volts - after 24 hours
This is about a 10 percent drop in charge in 24 hours.
Therefore, something is causing a significant drain in the battery.

12.51 volts - after starting, moving car, using key lock, turning car off
There was a big drop after starting, altogether a 26% drop of the charge.
12.64 volts - in 20 minutes the voltage is back to what it was before starting.

Here's an interesting FAQ about the state of charge of batteries.