I upgraded to iOS 7 yesterday (I have an iPhone 5) and have been noticing an odd issue. My phone will sometimes shut off and when I try to turn it back on it says the battery is drained. If I wait a few minutes and turn it back on it will say something like 39% battery remaining. Other times when it is on, the number jumps around. It can vary drastically from something like 6% to way over 50%! Yes, I have been playing with my phone more than normal, but fast battery draining isn't the issue. I can't figure out why I can have 50% one minute and a few minutes later it is like 5%! Is this a bug with the new OS?