I’ve been a happy iPhone user for several months now. Last weekend my battery suddenly started draining much faster than usual. I normally can make it through the day with plenty to spare, and the meter shows the battery depleting at a rate of just a few percent per hour. But for the last week it was draining at more like 20%/hour and I needed to recharge by afternoon. Searching the web, I found that this is not an uncommon problem, but not one with a single cause or a single solution, and there isn’t a lot of good information out there on tracking these problems down. Well, I managed to solve mine through a fairly thorough process of analysis, hypothesis, trial and error, and in the end a bit of good luck. The specific cause of my problem is unlikely to be the same as yours, but still, it may help to see how I worked through this, so I am posting about my experience in hopes that someone will find it useful.
Understand the problem
Some of the first things you will find when you search for information is generic advice like turn off WiFi and Bluetooth when not using them, or turn off the iOS parallax effect. I’m not saying these have no effect on battery life, but I had been using my phone for months, and had never found the need to mess with these before. Admittedly, iOS 7 was newish, but it had been working fine for weeks. Something changed on my phone, and I needed to find out what changed, not get generic battery saving advice.
Avoid jumping to conclusions
I had taken my phone off the charger and been away from my home for just a few hours when I saw my battery down to 20%. Obviously something was wrong. And right next to the battery icon was the VPN icon, which I had never seen before. 1+1=2, and obviously this VPN thing was what was killing my battery, right? I quickly realized the VPN had been set up by an app i had installed earlier that is supposed to reduce data consumption by compressing everything. Since that was the only significant change i had made on my phone that weekend, it sure seemed a natural assumption that this app was somehow killing my battery. So i uninstalled the app, and the profile it had made me install to go with it. No more VPN, but the battery problem persisted. I kept trying to reinstall and uninstall the app and otherwise solve the problem in terms of this app, but it turned out I was barking up the wrong tree. I wasted a lot of time on this wild goose.
Find the variables
After one my attempts the next day to solve the problem by uninstalling the data compression app, I thought for a while I had succeeded. First couple of hours off the charger and i was still in the 90’s. But that was still at home. As soon as I left for work, it started dropping like a rock again. The difference could have been a question of what tower I was closest to, or anything really, but since I was fixated on assuming it had to do with data access, I hypothesized this was a case of being on WiFi versus not. This time I didn’t just assume, though, When I got home I tested this theory by turning WiFi on and off and checking battery drain rates. I was right: on Wifi drain was 3-4%/hour, off WiFi it was 20%/hour. I also double checked by turning data off completely – no WiFi, no cell data. drain was back to normal. So clearly, the issue had to do with data access. Had this turned out not to be the case, I would have done more experimentation to get a handle on what was triggering the drain (or perhaps I might have found nothing prevented it, which also would have been good information).
There is goong to be a lot of trial and error in this process. And unfortunately, it takes time to perform each trial. For example, if I want to see the effect of turning off cellular data, that means turning it off, noting the battery level, then waiting at least a half hour to check again to be sure you aren’t seeing random fluctuations. A 2% drop in 10 minutes can happen even with your battery behaving normally, or it might mean things are bad – you won’t know until you let it run longer. So realize you may only get to run a handful of tests per day. Get through the rest of the day by turning off data or whatever your variable turns out to be.
Try the standard suggestions
You’re reading this, so obviosuly you are looking for suggestions. So was I, but because i was fixated on the idea that the issue had to do with one particular app that wasn’t even installed any more, I rejected a bunch of suggestions I should have tried. In hindsight, I should not have been so dismissive. One suggestion in particular would have led me to a solution sooner: try turning off iCloud. I’m not saying this will turn out to be your problem too, but the standard suggestions exist for a reason.
One suggestion I did try, with some trepidation but believing it would help rid my system of whatever evil this data compression app had left behind, was a complete backup, complete factory reset (restore) of my phone, and restore from backup. I was concerned that I might not get everything back, but I was wrong about that – my phone was pretty much exactly back to where it had been (just a couple of apps needed me to logback in or whatever). I was also concerned that the problem would get backed up too, and restoring from backup would reatore the problem. Unfortunately, I was right about this.
Be willing to try extreme measures
Once I realized I could completely restore my phone from backup, but that this brought the problem back, I hadn’t taken the step of verifying that a factory reset without a restore from backup would have worked. I was sure it would – nothing any app did to my phone could possibly survive a factory reset – but I knew this would be something I should verify anyhow. Plus I made a genius bar appointment at this point and figured they might want me to try this.
So I did the factory reset (restore) of my phone, and instead of restoring it from backup, I chose to set it up as a new phone, confident i could reset again and restore from backup later. After setting it up as a new phone I did two things and two thongs only to make the phone usable: I set up my Google account from mail/contacts/calendars, and I set up iCloud. I was confident the battery problem would have gone away, and that I could conceivably not restore from backup and instead simply reinstall all my apps and have a working phone again. Most of my data was stored in the cloud anyhow, so I wasn’t worried about that. I was totally prepared to go that route.
However, I was shocked to discover the problem had not gone away. Had it really been anything to do with any third party app, there is no way the problem could still exist. So it had to be either a hardware problem – but not the battery itself, since all continued to work fine on WiFi – or else some form of data access problem that was occurring despite not having installed any third party apps at all. In hindsight, it should have become obvious to me the issue must either be in my Google sync or else iCloud, since that was all that I had set up.
Know your limitations
Some of the online suggestions I found involved checking diagnostic & usage logs. I tried that. Needless to say if you’ve tried this, they were Greek to me. I wasted only a little time looking for clues there before realizing I had no concept of what good logs would look like, so my chances of identifying bad logs was basically nil. So even though this might have yielded an answer to somene who understands these logs, it was not looking like a productive option for me.
Be receptive to clues
Anything that is killing your battery is probably having other bad effects, some of which might provide clues. Battery is generally killed by excessive CPU use. This will generlly also result in the phone getting unusually warm. if it does not get warm, then maybe it isn’t CPU but something else. In my case, phone was definitely warm a lot, so no surprise. But one surprise was when I got a warnng from my service provider that i was nearing my data limit for the month. Odd, in that i was only half way there just a couple of days before. So obviously, whatever was using my CPU was also using data. I tried to get information about which apps were using CPU, and which were using data, but wasn’t finding what I needed to find. Apple does not make it possible to get per process CPU info, it seems. Data use, yes, in settings. And had it literally been a single app using all that data, I could have found that via phone settings, but in my case, it wasn’t showing that way. I did see that my phone itself was reporting much less data usage than my service provider was (I reset my usage statistics every month to make it easier to check on this), so I could see that it wasn’t “normal” data usage. I guess that much was obvious anyhow, but in hindsight that too was a clue.
At this point, had it not been for a stroke of luck, I probably would have turned off my Google account sync to see if it solved the problem (it wouldn’t have in my case), and then tried the same with iCloud (which would have solved it for me). Then I could have broken it down further – setting up my Google account sync with mail only but not contacts or calendars, then add contacts, then calendars. And similarly with iCloud, gradually adding back individual aspects of iCloud. Through process of elimination, I think I would have found the problem eventually.
However, I got lucky at this point. During this same week (!), I was noticing another apparently unrelated problem: the Internet Explorer bookmarks on my PC were misbehaving as were the Safari bookmarks on my iPad. Around the time all this had started, I had gone through and done some bookmark cleanup – IE was showing some duplicates, plus i had inadvertently placed on bookmark directly on my bookmarks bar rather than in a folder. In doing so, I had also installed the new iCloud bookmarks syncing facility for Chrome on my PC. Everything appeared to be working correctly, excerpt for one detail: in one of my bookmark folders, every time i tried rearranging the order of the bookmarks, they kept reverting to their former position. This was a minor nuisance but nothing more.
However, after watching these bookmarks rearrange themselves in front of my eyes for about the fifteenth time that week, it finally dawned on me: even though I rarely use my phone for web browsing, it too syncs bookmarks with my other devices. And if bookmarks were magically rearranging themselves on my PC and on my iPad, then they were surely doing so on my phone too. And it could for all be know be doing that constantly. I started to wonder if my phone and other devices were getting into some sort of bookmark syncing war, and if this was what was using up my data and running ,y CPU constantly. This was easy enough to test: I turned off Safari in my iCloud options.
Bingo! Instantly my battery returned to normal. That is, after turning off Safari sync, I turned off WiFi, checked the battery meter, waited half an hour, and when I checked the meter again it hadn’t moved. I then disabled the iCloud bookmark sync with Chrome on my PC, re-enabled iCloud sync with Safari on my phone, and again verified the problem remained fixed.
I spent a week with a phone that could only last a few hours off charger. It was enormously frustrating to me, and I have to assume it is to you to. I am posting this in hopes of helping you. Pay it forward and help others too if you discover anything you think could be useful.
Also, a but of common courtesy: if you’ve contacted anyone’s customer support looking for help, followup up and tell them you’ve figured it out. In my case, I had contacted the company behind the data compression app I incorrectly blamed for the problem at first, and I had also set up a Genius Bar appointment at the local Apple store. I followed up with both to let them know I had solved the problem on my own, and I also apologized to the app developers for assuming the problem was their fault.
I suppose at this point I should try reinstalling the data compression app to see if it really does work. But I don’t normally use more than my allotment anyhow. I should probably also see if I can figure out what went wrong in the first place – if the iCloud bookmark sync extension for Chrome was really to blame or if that too was just a coincidence. I tried turning it back on but couldn’t get it to work at all. That’s OK; I don’t use Chrome for anything but Google Docs anyhow. And right now I’m happy to have a working phone again and am not ready to rock the boat :-).