Voltage changes 12 to 14 volts constantly

You may want to hook up a scan tool and see what the PCM WANTS.
most Chrysler PCM charging systems are designed to control the system between about 13.1 and 14.6. It will actually select the voltage and can make a set point anywhere between that voltage range.
So example 13.2 will be alright if that's where the PCM wants it. It is to help preventing sulfating in the battery. Why charge the battery at a full 14.4 volts all day long if the battery is fully charged???