It's an iOS8 software bug and you can't do anything about it. Your battery is still lasting the same amount of time, it's just that the software updating the battery meter percentage reading is incorrectly coded/buggy.
Got a tip for us?
Let us know
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.
Jumps in battery percentage on iPhone 5 iOS 8.0.2
- Thread starter XeroAllusion
- Start date
- Sort by reaction score
It's an iOS8 software bug and you can't do anything about it. Your battery is still lasting the same amount of time, it's just that the software updating the battery meter percentage reading is incorrectly coded/buggy.
I have updated my ios that is now 8.1.3 ... And today I had like 20% then suddenly 9% , 4% and 2% .. In the same second as I plugged my phone in and it started charging, it showed 16% ?? Idk, is that just happening for no reason? I sometimes charge it on my computer, could that be wrong? I regret I didn't look at my "battery" app when it was 2%, maybe there was a different % ...
Did anyone try charging it to 100% then turning it off and back on right away?
I recall that worked wonders for the iPhone 4S on ios5, it was shown on several different forums at the time users found better battery life by doing that, not sure if that will help.
I didn't notice any difference myself, but I haven't made a log or looked at usage settings yet
Whatever this battery bug is, its a problem. Both my 5's have brand new batteries, yet I too experience this bug where the battery percent drops quickly
I recall that worked wonders for the iPhone 4S on ios5, it was shown on several different forums at the time users found better battery life by doing that, not sure if that will help.
I didn't notice any difference myself, but I haven't made a log or looked at usage settings yet
Whatever this battery bug is, its a problem. Both my 5's have brand new batteries, yet I too experience this bug where the battery percent drops quickly
My 5s went from 31% to cutting itself off and displaying the battery low image on the screen while out for a run. I had just looked at battery life since I was using the flashlight and then it cut off. Seems to me it's just a software issue with updating the % battery life left. Apple probably has other fixes higher on the list, ala anything security related...this is a nuisance but harmless.
Hello people , i had the same issue on my iP 6 and the solution was easy : upgrade to the latest 8.2 version and calibrate the battery by using the phone till it goes off automaticly then charge it for around 4-5 hours and then press the power+home button until u see the apple logo this will help for sure it fixed mine 
good luck guys
good luck guys
Hello people , i had the same issue on my iP 6 and the solution was easy : upgrade to the latest 8.2 version and calibrate the battery by using the phone till it goes off automaticly then charge it for around 4-5 hours and then press the power+home button until u see the apple logo this will help for sure it fixed mine
My battery is perfectly calibrated. The jumps, such as 61 to 59% etc are to do with iOS8.
Not really i had this issue on my iP 5s from iOS 7 out of the box , calibrating the battery once again is always good it won't hurt you know , just give it a try it will give some results for sure . Restoring phone via iTunes as a new one does help aswell !
The actual capacity of a battery decreases as the battery ages through an irreversible fading process. This capacity loss occurs both with active use, correlated with charging cycles, and with inactivity through self-discharge. The device may even come with substandard batteries. However, the amount of loss is linear with time and accelerates with increasing temperature. Smartphones do not typically employ sophisticated techniques for estimating the usable capacity with the basic solution basing on simple charge cycle estimation and then using an offline calibrated lookup table to find the state of charge or battery level given the charge cycle.
Battery level or State of Charge (SOC) estimation in modern smartphones cannot capture the usable capacity of the battery run time, and thus have unreliable SOC estimation. This inaccuracy manifests as sudden jumps in the battery level, and can result in unexpected shutdown of the device.
Therefore, there are two issues; (1) The battery capacity is reduced, and (ii) The device is unable to estimate the capacity loss. The detail about this can be found in the following paper.
Page on acm.org Sudden Drop in the Battery Level? Understanding Smartphone State of Charge Anomaly.
Battery level or State of Charge (SOC) estimation in modern smartphones cannot capture the usable capacity of the battery run time, and thus have unreliable SOC estimation. This inaccuracy manifests as sudden jumps in the battery level, and can result in unexpected shutdown of the device.
Therefore, there are two issues; (1) The battery capacity is reduced, and (ii) The device is unable to estimate the capacity loss. The detail about this can be found in the following paper.
Page on acm.org Sudden Drop in the Battery Level? Understanding Smartphone State of Charge Anomaly.
Another reason why I'm glad I've left my 5 on ios 6.1.4 using it as an ipod, internet radio, watching Dish Network on Dish Anywhere, etc. My iphone 6 is still on 8.4. just got a 6s Plus this week still on 9.0 so far.
I'm a firm believer the ios a phone is born with is the best performing one for it.
I'm a firm believer the ios a phone is born with is the best performing one for it.