Fixing the iOS 5 battery drain problem

I’m sure you are already upgraded to iOS 5 by now if your iPhone, iPad or iPod touch supports it. Well, even if you aren’t yet, it’s probably just because you didn’t have the time yet.

It’s only been a week since I’ve updated my iPhone 3Gs and I’ve to say that it’s the best OS that’s landed on the iPhone 3Gs. The performance is great and it also feels much faster than iOS 4.x. Overall, I’m a happy camper that my 3Gs has received a new lease of life.

However, there was one issue that bugged the heck out of me. And that’s the initial battery drain problem. Just do a google search and you’d see a lot others also face the problem. If you’re not one of them, such as my wife’s iPhone 4 which didn’t suffer any battery drain issues at all, that’s great! But if you do, then here’s a tip how you can make sure you get to make a phone call when you need to.

What’s the root cause of the problem? I’m really not too sure. Without jail breaking the iPhone and gaining access to the OS commands to see what’s the process or application that’s utilizing all the CPU in the background, I really can’t tell. All I know is that somethings running in the background and loading up the CPU utilization. As you can see from the screenshot on the left, the phone is not idle at all.

There are many theories what’s causing iOS 5 to drain the battery. Some faulted it at the location services features, especially the Weather app’s notification widget that is able to provide you with weather reports based on your current location. Some instead faulted it at the iCloud sync. But even after shutting down all these features, my phone was still losing its charge really fast. Also, I wouldn’t want to get a ‘dumbed’ down phone too by shutting down all these features, would I.

So, the problem is obviously not location services or background syncing of iCloud.

Then I noticed something when i was playing around with the settings. It seems that when I shut down WiFi and Cellular data and thus, isolating the iPhone from any network connection, the phone cooled down. And sure enough, when I check the CPU utilization of the phone, it has dropped significantly as you can noticed in the screenshot on the right.

After that, even turning both WiFi and Cellular data back on, the CPU continued to be idle and thus, relieving my iPhone from stressing itself out and draining the battery at the same time.

It wasn’t till the next day when I noticed that my phone was again draining it’s battery. I did the same again and turned off both WiFi and Cellular data. Sure enough, it stopped the phone from stressing the CPU and almost full load.

There you go, the solution to this problem is to disconnect your iOS 5 device from the network!

My suspect on what’s happening? Perhaps it’s trying to re-index the filesystem, or doing a full scan of the phone. Perhaps to establish a full catalogue of the filesystem on iCloud for backup sync comparisons. Who knows? If you do, perhaps you can shed some light here. But whatever it was doing, it seems that it stops after a couple of days. My iPhone 3Gs no longer randomly goes into full CPU utilization anymore and I didn’t even turn off any features.