Does leaving WiFi on drain battery life?

jdxlee

New Member
Sep 26, 2007
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#1
I'm sure this is a stupid question, but does leaving wifi "on" drain the battery life significantly when the iPhone is locked?

Besides bluetooth and auto check for emails, does anything else drain the battery?

I'm trying to figure out if I have a battery issue or not, the battery on my iPhone seems to flux often, some days I would be able to go fro 3 days w/o a charge and others, I would need to charge the very next day...
 

Hawk

Genius
Gold
Aug 2, 2007
6,682
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#2
there are some people on here that say no, but it depends on how you are using it. If you are not connected to a network an actively transmitting over it, then all WiFi does is search for networks.
While browsing and email over WiFi is significantly faster, meaning you spend less time getting your data, leaving it on is a different matter, especially if not connected.
I spoke with an Apple genius this past Saturday about my battery life, and he stated that ANYTHING using an antenna is going to cause significant battery drain.
Leaving BT on connected to a headset or not means that it constistantly sends a handshake signal out to either verify that the device is there, or to find a device. It's the same with WiFi. If not connected, it will seek out any available signal to connect to. And even when connected, if not in use, it still talks to the device transmitting the signal, and that requires a fair amount of power- even if it's only for a few seconds at a time.

Test it yourself. Charge up the phone, clear the statistics, and then leave WiFi on. When it notifies you that you are at 20 %, write down your statistics, clear them, charge up, and then try to duplicate usage with WiFi off and see how long the phone lasts. I'd hazzard to say that you might get between half a day to almost a full extra day more with WiFi off.

Other things to help with battery life are as follows:
When you finishe using the web, close all extra windows, open a new blank window, and then go back and close the one you were browsing on. This prevents any "background" downloading or updating of the page. Another way to do this is hold the home button till it closes, but holding the home button to close any application is like using "end task" in the Task Manager in Windows. Not exactly recommended, but not fully discouraged either.
also try setting your brightness to as low as you can while in very bright areas or out in Sunlight. the lower the better.
 

Maahu

New Member
Bronze
Sep 19, 2007
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0
#3
I'm sure this is a stupid question, but does leaving wifi "on" drain the battery life significantly when the iPhone is locked?

Besides bluetooth and auto check for emails, does anything else drain the battery?

I'm trying to figure out if I have a battery issue or not, the battery on my iPhone seems to flux often, some days I would be able to go fro 3 days w/o a charge and others, I would need to charge the very next day...
I've had this same experience, and from what I've seen, it's not the leaving Wi-Fi on per se, but leaving an open connection active on Safari.

I've had web pages hang while loading; the browser continues to try to load, sending and receiving packets, but never completing the page and closing the connection, resulting in continuous use of the Wi-Fi radio (or EDGE for that matter), and a significant drain on the battery.
 
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jdxlee

New Member
Sep 26, 2007
22
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0
#4
I have actually charged the iPhone fully and will be putting the Wifi to the test, I am starting out w/ Wifi off and will report once results obtained...
 

voldak

New Member
Sep 24, 2007
21
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0
#5
I've done some testing with the wifi as well.

I noticed that on my iPhone (1.1.1) when I have wifi connected and then lock the phone the wifi will only stay connected for about 20 seconds after the lock, before it goes into wifi standby or something. I have a Cisco 1300 AP at my place of work, it has lightup displays on the front. The second something connects to it the LED color changes, this is about as scientific as I got with the testing.

Also, if my phone identifies a wireless network and is connected to it. It uses far less battery than if you leave your wifi on and have it "not connected" or searching the whole time.