Why does the battery in my volt keep dying?

What is your question?

If I dont run my car for a day or two my battery completely dies. No lights come on etc. I have to jump it. Have had the batteries checked for dead cells etc. I have replaced the battery and it still does this. No other issues. No lights on etc. There is nothing that points toward any other issue. I have made sure that lights etc are not being left on as well. I double and triple check.

What makes this problem better or worse?

When I dont start it for 24 to 48 hrs.

How long has your 2012 Chevrolet Volt had this problem?

Months