I had an on going similar problem with my car for about 2 years now. It just never seemed to crank over like I though it should. I read a post a couple of weeks ago that got it all straigtened out.

First be sure there are no lights being left on. I did have one occassion where my funny little trunck light got left on. You might want to check the glove compartment light is switch is working properly also.

Second (What really fixed my problem) I got out my dremel and a wire brush and baking soda and cleaned the devil out of my terminals and post. Before I did this my battery would go dead after 3 to 4 days of letting my car set. Now it starts up after a week of setting with no problem

Hope this helps
Brad