Will The Radio Run The Battery Down?

My Dad has a Kia Optima and my friend and I wanted to sit in the car and just listen to the radio but we weren't sure if it would kill the battery. There are 4 options on the key slot (Off, ACC, On, and Start). We set it to ACC and only the radio worked (Windows, AC, Locks, etc didn't work). If we used that would it be OK?