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iOS 8.1.2 Battery Bug: How to Fix

About a week ago I updated my iPhone 6 and iPhone 5S to iOS 8.1.2 and guess what? My battery on iPhone 5S was draining like crazy! It went from 100 to 17 percent in just 4 hours. The battery meter was also acting weird. It was jumping around and dropped from 100 percent to 92 and so on. I had to always carry a backup battery with me all the time.

Battery Life iPhone 5S

I looked up web and tried every solution about iOS 8.1.2 Battery Bug that I found. I erased my iPhones and did a complete factory reset. I restored my iPhone and set it up as a new phone too but that didn’t helped either. My iPhone was not warming up and the standby and usage counter displayed correct readings too.

Resolving the battery Draining issue on iOS 8.1.2:

Calibrating Battery:

I tried to calibrate my battery by completely draining it to 0 percent and then charging it to 100 percent but that was a kind of fail for me because my iPhone turned off at 7 percent or sometimes at 12 percent too and when I plug it to charge, it turned on immediately showing that I have 20 percent battery left. It was a fail too.

Third-party Lightning Cables:

I was using a third-party lightning cable and I thought that it has damaged my iPhone’s battery. I googled about this and found that using third-party lightning cables will damage the U2 IC that is responsible for charging the iPhone, sleep/wake button and some USB functions. Once the battery is 100 percent discharged, it will not charge it up again but will continue to charge if you have some charge left in your battery. This was not my problem either.

Replacing Battery:

Some people even suggested me that I should get my battery replaced because my battery’s current charge capacity was about 80 percent as compared to designed capacity. I contacted Apple for a battery replacement because I knew I will not find genuine replacement battery from elsewhere.

I came across few people who told me that they are still experiencing same battery problem even after replacement. I changed my mind about replacing my battery and kept it as my last option for when nothing works out for me.

What was the problem?

On 18th December, it was pretty cold outside. I took my iPhone out and it dropped 3 percent after just unlocking the device, and when I put it back in my pocket and looked it up again, it was back up by 2 percent. This thing seemed somehow weird to me and did a quick google search about lithium-ion batteries and cold temperature.

iPhone 5S Battery Bug Fix

I found that using lithium-ion batteries in cold climate can decrease the efficiency of battery. Using it in room (or slightly warm) temperature will increase the flow of electrons in battery and it will increase its performance. While cold weather increases the internal resistance and hence reduces its capacity. This indicated that the battery issue was also (or completely) due to the cold weather around here.


I decided to discharge my iPhone’s battery completely. It turned off around 6 percent battery while I was on face-time call. I tried to turn it on but it didn’t come on. I then covered it in blanket and left it there for about 10 minutes, I then tried to turn it on and it came back on. This time the battery was on 11 percent. I used my iPhone and it turned off at 2 percent battery this time.

I then again repeated the process and it turned on again. This time the battery was on 8 percent. I used my iPhone again to completely discharge it. This time my iPhone lasted for quiet a while and stayed on 1 percent battery for almost an hour and them turned off. I then again tried to warm it up in blanket again but this time it won’t come on meaning that battery has discharged 100 percent.

I left my iPhone in blanket for the night and plugged it in for charging next morning. I left it plugged in for 5 hours and then restarted my iPhone. I started using my iPhone and found that the battery was acting normal this time. It gave me about 7 hours of usage and 19 hours of standby before battery went bellow 20 percent.

iPhone 5S Battery Bug

I then plugged it in when it was at 18 percent and charged to 100 percent again. After this, my iPhone is back to its normal battery life. I am very happy now with my trusty iPhone 5S.


I actually calibrated my iPhone’s battery by completely discharging it and charging it to 100 percent. I did a complete factory restore from iTunes and set it up as a new iPhone before calibrating battery. To restore iPhone via iTunes connect your iPhone to your Mac or PC and turn Find My iPhone off. Then press home and sleep/wake button together and release sleep/wake button after 10 seconds while still holding home button. Your iPhone will enter in recovery or DFU mode and iTunes will ask you to restore it.

iOS 8.1.2 Battery Bug

Even though my battery is working fine but when I restart my iPhone after a full charge, the battery usage and standby counter forgets usage and standby time. This is a bug in iOS 8.1.2 regarding battery performance which we hope Apple will fix soon in their upcoming updates.

If you found this article useful then share it with your friends if they are experiencing same problem. If you have any question or suggestion related to this bug or battery draining issue then leave it in comments bellow.

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