4.0.2 guzzling my battery. Your's too?

Well, talk about fighting for your corner but, after 20 minutes of justifying my problems, I have a replacement phone (#3) although handed over quite unconvincingly. Battery tested as green but the genius guy seemed to think there was nothing wrong with the phone losing 5-10% on standby. When I said I get to 30% at late evening with light use and after a morning's charge it seemed perfectly normal 'compared to his own phone'.

OK, so this device is week 30, factory 83 and was pre-loaded with 4.0.1. Currently it's wall charging (cold handset which is a good sign) from 67% out the black box to 100% + whatever it also gives me. So when it's had time to settle, I will restore the unit as new, update to 4.0.2 and see how we go from there...

I have hopes on this one 🙂

When i tried to update to 4.0.2 the first time, i got that error -1001 i think, or something....

When i went through the restore, it erased everything off of it clean, and then installed the new 4.0.2 - and then later synced up all of your information.

media360degree wrote:
Ladies and Gentlemen,
I updated my iPhone 4 to iOS 4.0.2 on 11th Aug night, and I have experienced a much faster battery drain than before.

Hi, I'm late to the party, but as I've had an iPhone for 3 years and been through a lot of updates I think I can contribute a slightly different perspective.

First, my battery life with 4.0 was much better that with 3.1.3. When I updated to 4.0.1 it dropped significantly, but, applying what I had discovered with previous releases I was able to fix it.

The key point is sudden battery drop is not a defect in the release you just installed, it is caused by the update process itself. It's random, and only affects a few people, but it is a real problem for those it does affect. If you read backwards in time through the forum you will see reports of battery performance problems after EVERY release since the first. And pleas to go back to the previous release to fix it. Those who do go back usually find the problem is not fixed. Thus, the only common factor is the fact that you updated, not what you updated to.

I've never seen a clear explanation of why this happens, but I assume it's because there is information stored in the phone that is corrupted by the update process, which then breaks an app or two after the update. Maybe it's just because code or data has a new location in the phone.

I've also observed, from my own experience, that the most common culprit is the mail app, especially if you have Push email. My fix, which has always worked for me, is to first Reset Network Settings and reboot, then go into Settings and delete the Push email account entirely. Reboot, and add it back.

Other users have reported that they have identified one particular app that causes their problem, usually social networking apps like Facebook.

But the key news is that you should try to fix it in the current release, not try to go back.

Hello!

Although I have a 3GS, I bought this about 3 months ago. When I updated to 4.0.2 my battery life was terrible. In under 3 hours with limited use (checked email once, called my boyfriend and sister once), my battery life decreased from full charge to less than 50%.

I am not a happy camper. I wonder if I could do a reverse update to 4.0.1... I had no issues with that.

Ange

um i believe u just do a restore thru itunes and start the phone as a new phone. then update to 4.0.2

Hello,

I too noticed fast battery drain under 4.0.2, but after restoring as a new phone i now get approx 30hrs on a full charge, That`s with about 4+ hrs use and the rest is standby. But one thing that i have noticed is that the battery % and the actual batter meter do not correspond with each other.

For example the batter % may read 67% but the batter meter will show that you still have a good 70-80% left.


I now find that i get a true battery reading if i turn the % off under settings.

The only reason i noticed this when i gave the phone a full charge was that the % said 100% but that battery was still charging (it took about another 10-15 mins until battery was fully charged).

In fact the battery life may change dramatically depending on whether you are using some multitasking enabled apps.

Indeed, some apps, like VoIP apps or background audio compatible apps, or even IM apps can make the battery to drain faster than expected.

Indeed, VoIP or background audio app are kept active because they are using one of the multitasking background service offered by iOS 4. IM apps are using push notification and so are monitoring the network regularly which can also participate in draining battery faster, even when the phone is in stand-by.

So to get a better battery life, you must take care to quit any app that can use any of the background services or push notifications (really quit using the minus round red icon on the task switching dock (appearing by double tapping the home button)).

I'd love that Apple offer a "quit all button", that would make this a lot easier.

89% 21 hours, 40 mins standby, 3hrs 2 mins usage on one charge is all I have to say 🙂