If the battery goes dead after a couple of days....you could have a draw. A good way to test for that is put a digital volt meter/amp meter in series at the battery. You have to wait about 45 min to let the modules go into sleep mode. You should have no more than .050 milliamp draw. If you have more than that...you can start to remove fuses to pinpoint the circuit with the draw. The alternator could be intermittely not charging....but it sounds more like that you have a draw. I would have the alternator load tested...to see if its Amp output is good. If you need anymore help..please let me know.
Well thats good that you don't have a excessive draw. It could be the battery on its way out. I have seen batteries do some strange things when they get old. I would get the alternator load tested to eliminate that as a cause. Its hard to test that alternator without test equipment. You can do a small test by watching battery voltage and turning on a lot of things in the vehicle....like headlights, blower fan, wipers ect....but you really cant see amp output....If you need anymore help please ask
Thats good that you pinpointed it down to the battery. The light flicker might be cause from the low voltage...but not sure. If you need any more help...please ask