disconnect the battery and place an ammeter between the hot and the battery and measure to see if there is a parasitic drain on the battery. You can also take it up to Dodge and get a GR-8 test. It could just be a bad cell in the battery.
The term Ignition-Off Draw (IOD) identifies a normal condition where power is being drained from the battery with the ignition in the OFF position. A normal vehicle electrical system will draw from five to thirty-five milliamperes (0.005 to 0.035 ampere) with the ignition in the OFF position, and all non-ignition controlled circuits in proper working order.
If the IOD on your car is more the 35mA there is a circuit/module that needs to be repaired. I had it happen because the memory module cable connection was loose. Memory module is under the driver seat.