2004 Dodge Ram 1500 pickup will not hold charge on battery

My husband's pickup will not hold the charge on the battery.  The battery was only 6
months old.  Had it checked, was good.  Took truck to Dodge dealership for repairs.  
They told us the "cluster" was bad.  They had to remove the entire dash to replace.  
Truck was fine for two days.  Brought it home.  Two days later, dead again.  Returned
to dealership.  Three days later they said it was fine and had no problems with battery
going down.  Picked up truck, brought it home.  Next morning, dead again. Checked
the alternator, and the battery is not showing a discharge. Replaced the battery.  
Truck started the next two days ( though we did not actually drive it for any distance) .
On fourth day, went to drive the truck and it was dead again.  Not finding anything  to
run the battery down, just won't run after two or three days of sitting.  Frustrated!