I recently replaced the 20GB hard drive in an iPod 4G clickwheel with an IDE to CF adapter, CF to SD card adapter, and a 128GB SDXC card. I also decided to replace the original battery because, why not?, it's 15 years old. But I'm now wondering if the battery replacement was necessary. On the OEM battery, I was getting 12 hours of playback time with the SD card. Can I expect much more than that?