WiFi is the cause (of at least my) battery drain problem

[Avenger]

After going crazy on figuring out why my iphone 4 was draining a few percentage points per hour, I figured out that it was because I had WiFi on along with the regular phone being in standby. When I turned the WiFi off, the battery didn't even drain 1% over night.

Before you ask, yes I had the "Ask to join networks" options turned to off. Someone in another thread is theorizing that the WiFi connection on the new iPhones/iOS 4 is persistant even when in standby which is why the battery drains. I'm not sure about this but I know what I've seen related to battery drain.

For those people with battery drain problems in standby, please turn WiFi off and let me know if this solves your problem. I'm curious if it is global or just specific to my hardware (ie wireless router setup).

 

[xxjonoxx]

I am thinking you are correct, as I turned my WiFi off and it's been 30 minutes and I haven't lost a single % yet with it in standby. Before I would have been down probably 2% in that time.

 

[spinstorm]

Another bug?!

Call apple and complain as this is definitely a software issue and I have it too...

It's easily fixable.

 

[Avenger]

Thanks for the confirmations. I wonder if running WiFi in 802.11g instead of 802.11n would make a difference. I'm running 802.11n. Does anyone with an 802.11g only router have this WiFi standby drainage problem?

 

[Gav2k]

It's not a bug it's part of ios4.

In 3.1 the wifi was only on when requested by the user or software.

In ios4 it is always on.

 

[Avenger]

It's not a bug it's part of ios4.

In 3.1 the wifi was only on when requested by the user or software.

In ios4 it is always on.

Is 3G access always on as well even if the phone is in standby mode? If so then why doesn't it drain the battery more since I have always read 3G consumes more power than WiFi. If this is a feature, I guess it was needed for some reason but it really hurts the battery life.

 

[ryuuzaki]

It's not a bug. Every cell phone suffers from losing a lot more juice over wifi than over 3G.

Read this article from MIT's Technology Review:

http://www.technologyreview.com/communications/25651/?a=f

 

[Jumpie]

It's not a bug it's part of ios4.

In 3.1 the wifi was only on when requested by the user or software.

In ios4 it is always on.

well, that explains the battery drain so quickly. I wondered cuz when I had it off and used just 3G, battery life was pretty durn good.

 

[Puma559]

I'm going to have to try that. I went to sleep with 29% battery and woke up with my phoned turned off because the battery had drained.

 

[telarmago]

I too have noticed a ~2% drain/hour that seemed too high. I will test this out.