What size is the battery and is it a deep cycle or a starting one? A starting battery is not designed to be discharged to far and can be damaged.
What type of radio do you have a standard one or high power with an amp subwoofer, ...? If you are running an amp an other high end electronics you need to calculate the amp/hour draw to determine what size battery you need for the time you are sitting.
Finally how many hours are you sitting with the radio on?
You may want to consider a second battery however I know space is tight on a 1700.
1997 2400 SCR
5.7 Vortec / Bravo 2