Two of my old trusted XBox 360 controllers recently stopped working. The first one seemed to be at the end of its life and I threw it away. On the second, I had another 360 controller handy and tried swapping out the detachable battery box and it worked. So, $6 later, I kept the previously non-working controller, and I have a backup in case one of the battery trays inevitably stops working due to corrosion.