When I first got the 5s on release day, I was losing under 8% overnight. Recently, I have been losing 35-40%. I have not changed any setting and I haven't changed any habits since the 4s. I have tried restoring from backup, problem still existed. I went to the Apple store and the "Genius" restored it as new to check if the battery problem persists, it still did lose 35-40%. I went back, they gave me a hard by saying even if they replace it, the phone would still be losing the same amount. They said that there was a known battery issue and that they would replace the phone if the serial number on my phone match the serial number of the phones affected. Mine wasn't in that group. They soon replaced after being persistent. My mom's 4s is losing under 10%, my girlfriend's 5 is losing under 10%, brother's 5s under 10%. All AT&T, same configurations on settings (Mail set to MANUAL,) everything else was the same. This wasn't happening to my 4s, my iPhone 4s was losing under 10% overnight. What could I have done? I want to know to prevent it from happening to this replacement. The only thing I have that they don't is a fake iOS7 compatible lightning cable, and an Anker portable charger that I use with the ORIGINAL lightning cable. Any help would be great! P.S. I choose not to plug my phone in overnight because it is my wish. Please don't bash me for not doing so. iPhone 5s 32gb AT&T and iOS7.0.4 ---------- I have only used the Anker portable charger for a week in Vegas. I usually charge through my MBP's USB port and not the supplied wall charger. Does the USB and wall charger have any difference? If so, which is better?