So I had an iPhone 5S that I bought secondhand off ebay. The previous guy must have used it extensively as the battery life was questionable. So I purchased a battery off ebay, specifically this one: http://www.ebay.com/itm/310944646613?_trksid=p2059210.m2749.l2649&ssPageName=STRK:MEBIDX:IT The price was great, and the guy has 99.6% positive reviews. However when I first got it, it showed battery life as 31% and shut off. I charged it up overnight, and the new battery does in fact seem to discharge at a slower rate, however today at 81% the phone again spontaneously shuts off. Plugging it in brings it back to life immediately, but unplugging it again immediately shuts it off. Is it possible that the install was incorrect and that there's something other than a bad battery at play here? I know it's not good to be cheap, on the other hand, many people have had success with relatively inexpensive 3rd party batteries.