I purchased a used iPod Nano (7th Gen) from Cowboom for a decent price and after using it for a while, I realized that either I'm doing something wrong. I listened to music all day yesterday via Bluetooth and my battery did not run out. Last night, I came home and charged it to full. This morning I removed it from the charger and just let it sit (I forgot to take it with me). I come back a few minutes ago (so that would be roughly a 12 hour period) and I check my iPod and the battery indicator is red (very close to running out of power). BT was still turned on, but it wasn't connected to anything. Music wasn't playing and I can't figure out what exactly was the issue. I thought it might be the fact that the iPod was used so battery capacity dropped or something. But I'm not entirely sure. Any clue what's up with this?