Chrysler 300 M 2000 -- Intermittent battery draining problem

Sometimes the battery is drained, other times everything works OK.  This is
hard to explain, but I noticed that if I flick around the headlight switch,  that
sometimes it will drain the battery and sometimes it won't.  Another way of
putting it, if  The headlights are set to automatic and I don't touch anything ,
sometimes the battery will drain and sometimes it won't. But if I mess with the
headlight switch every 10 minutes when I'm driving,  that will ensure that my
battery will be charging at least through one 10 minute period.  So if I'm
driving for one hour, I will mess with   The headlight switch six times, and It
will guarantee is that I won't have a dead battery when I get to my destination.
But if I don't mess with the headlights, there's a 50-50 chance that the battery
will be dead when I get to my destination