The Lithium-ion era issue is somewhat subjective and is a difficulty that makers have usually avoided discussing. what's proverbial, is that the iPhone and cell phones batteries lasts for less than a finite range of cycles. Apple claims that “A properly maintained mobile phone battery capacity is intended to retain up to eightieth of its original capability at four hundred full charge and discharge cycles.” However, this claim is predicated on ideal situations with correct maintenance. In reality, the effective lifetime of the mobile phone battery capacity falls somewhere between three hundred and five hundred full cycles. A full battery cycle is outlined as an entire charge and discharge of the battery. Therefore, discharging the battery to 50% and recharging it equals a half cycle and repeating the process would make one full cycle. The fact that continues to be comparatively unknown concerning the metallic element particle batteries found within the iPhone and alternative devices is what quantity power the battery retains, in spite of whether or not it's in use or not. this implies that notwithstanding your mobile phone sits in an exceedingly closet for a year while not use, odds area unit the battery capability has deteriorated to some extent. So how much will the battery capacity of the mobile phone be reduced over time? the precise number is wide debated, however some estimates claim as high as a twenty fifth capability loss per annum et al as low as ten. in line with batteryuniversity.com, “Some capability deterioration is noticeable when one year, whether or not the battery is in use or not. The battery oft fails when 2 or 3 years.” rock bottom line is that the mobile phone battery capacity don't last forever, and if your battery is over a year previous and showing signs of reduced capability, you'll want A battery replacement.