I recently purchased a used iPhone 5s for what seemed like a very good price of approximately $100. The phone is in really good condition with the exception of the battery. I've updated it to iOS 9.3.5 but the battery seems to loose approximately 10% of its charge per hour just on standby. I have barely any third party apps installed and the battery status in settings does not indicate that any particular app is responsible for substantial drain. If the phone is actually being used, the drain is even greater. I have read that the 5s battery was not the best to begin with... assuming the phone was purchased and heavily used since its launch, should I assume that the battery is pretty much out of charge cycles or is this just typical 5s performance? A local phone repair shop charges $40 to replace batteries on these phones which, to me, would be worth the cost if it improves things. Would a new battery improve performance? Thanks!