I'm happy that you haven't had this problem (although without a screen I'm not surprised you get multiple days use from a single charge.) Unfortunately, lots of people are not so fortunate, and I'm one of them. There are a number of known, reported, acknowledged bugs that might or might not be fixed in the latest patch update to 4.3 that cause "Android OS" (actually a partial wakelock held in the kernel) to stop the phone from going into deep sleep and draining the battery. For example, https://code.google.com/p/android/issues/detail?id=52034 is one such bug. There are others (I don't use a wireless charger).

Until whatever byzantine download scheduler deigns to push the patch to 4.3 to my phone, it's basically unusable.