hello guys this is about my iphone 5. i got it a week ago as it was a spare phone in my house but was still used NOT switched off. it came with ios 7.1.2 but i have issues with its battery life. at first charge the phone died at 20% while battery was draining quite rapidly. i checked the battery current capacity on ibackupbot and it was about 1050/1430. i did battery calibration by completely charging and discharging it and the battery life seems to be improved. but when i checked the current capacity it was now 1200/1430. since thn i am doing complete charge/discharge and i have also upgraded the phone to ios 8.3. sometimes my phone dies at 1% but other times it dies at around 10%. today the battery capacity has increased as well its now 1300/1430. whats the reason behind it. i am getting 16 hrs standby time and 6 hrs usage time on full discharge. why does my battery capacity fluctuates. P.s i have not played with hardware yet nor have i changed the battery.