Okay, we are making some progress in deciphering the terminology, but unfortunately the OP has still not answered questions, such as those posed by LedLawless and Bemis.
Mr. Martin:
Are you operating an air compressor while the engine is shut off?
If so, this was not wise. The manual for every electric compressor that I have owned specifically states “do not operate this device unless the car’s engine is running”.
How long did you listen to the CD player? Was this also while the engine was shut off?
If you listened to the CD player for more than…let’s say…20 minutes with the engine shut off, this was also not a wise thing to do, especially if the battery is more than a couple of years old.
And, that leads to other questions that need to be answered, namely:
Is the vehicle normally subjected to a lot of short-trip driving?
What is the model year of this vehicle?
How old is the battery?