Possible Wi-fi Battery Saving Method - Needs Confirmation From Other Users


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  1. ziggy682

    ziggy682 Member This Topic's Starter

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    I stumbled upon a new wi-fi setting yesterday that is fairly hidden and not mentioned in the manual at all, so I though I'd share it here.

    First, a little background and explanation, then I will share my new findings with you all. It has been confirmed in other threads that the wi-fi radio uses considerably less power than the EV-DO 3G radio in the Hero. When you think about it, it's actually pretty simple because the signal only has to travel 100 or so feet for wi-fi, vs. several miles for the 3G radio. Whenever I'm at home or anywhere else with wi-fi, I always switch the wi-fi radio on, and have found that the battery lasts much longer. Whenever the phone is awake, and you're actively connected to a wi-fi network, it seems to shut the EV-DO radio down completely and rely solely on the wi-fi data for data. This has been confirmed as true, because there are some programs out there (i.e. Sprint TV) where you have to turn wi-fi off, because they will only access with the EV-DO radio. You obviously want to turn the wi-fi off whenever there are no networks around, because it will actively search for networks whenever it is on, and will run the battery down.

    So, I noticed every time I would wake my phone up after I hadn't used it for a while, it would be using the EV-DO radio, and would take a few seconds to re-connect to my wi-fi network. I couldn't quite figure out why the phone would revert back to EV-DO when sleeping, then connect back to wi-fi only after waking the phone back up. Yesterday, I stumbled upon a new menu I hadn't seen before where you can change this behavior. Check this out.

    Menu->Settings->Wireless Controls->Wi-Fi Settings->Press Menu Again->Advanced->Wi-Fi Sleep Policy

    The description for this menu reads "Specify when to switch from Wi-Fi to mobile data."

    Within this menu, there are three options.

    "When screen turns off."
    "Never when plugged in."
    "Never."

    The default setting is "When screen turns off." So, even with wi-fi enabled, whenever the screen turns off, your phone automatically reverts back to the EV-DO radio. As we all know, your phone is still transmitting data a good portion of the time, even when you're not using it. So, even with wi-fi turned on, the phone is still using the 3G radio to communicate while the screen is off.

    I switched this menu setting to "Never" as of last night. This forces the phone to always use wi-fi whenever it is turned on, and you are connected to a network. Since then, whenever I wake up my phone it is still showing the wi-fi icon, and I haven't seen the EV-DO icon at all like I used to see for the first several seconds.

    I was at home most of the day today, connected to my wi-fi network. I left the house twice for probably about 2 hours total, and I switched off wi-fi both times I left the house. I used the phone fairly lightly today, since we had a family day, but that still consisted of a good bit of browsing, some email usage, light texting, reading twitter updates every two hours, and half an hour playing a video game. Also, I always leave my GPS switched on as it never activates unless I open a program that requires it, and it always switches back off after I'm done. I took the phone off the charger at 9:30 this morning, and it is now 11:50 pm as I'm typing this. So, we're looking at over 14 hours today. The phone hasn't touched a charger since this morning, and I am sitting at 52% battery life, and I'm about to plug the phone in and go to bed.

    I have never seen anywhere near this kind of battery life at the end of the day. I am usually below 15% after this kind of usage. I'm not sure if this was just a freak day, or what, but I really believe changing this one setting had a profound affect (effect?) on my battery life.

    If anyone else is around wi-fi most of the time, please try this out and keep this thread active with your findings. If other people have the same results as me, we might just have a new battery saver to work with.
     

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  2. meangreengdub

    meangreengdub Well-Known Member

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    I'll give it a try. Good find. Makes me curious to hit menu in every new screen that opens haha!
     
  3. Archon810

    Archon810 Well-Known Member

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    I'd say it's a good idea IF you're correct about WiFi vs 3G. I think that assuming that it takes more power to receive the 3G signal vs WiFi just because of distance is incorrect (it may take more power to transmit it but receiving depends on other factors).

    Curious to see everyone else's findings though.
     
  4. ziggy682

    ziggy682 Member This Topic's Starter

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    Yeah, after I found that one, I went through hitting menu on every screen in the settings, and that was the only one I've found.

    You know what else has surprised me several times? Long pressing on things in various programs nearly always pops up with some kind of useful, context-sensitive menu.
     
  5. g0tr00t

    g0tr00t Well-Known Member

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    *smacks forehead* - I really need to read that user manual. Thanks, I changed to never, we'll see what happens.

    Thanks! :D

    +1
     
  6. beejreit

    beejreit Member

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    I'll be giving it a try and reporting my results
     
  7. mamiamjo

    mamiamjo Well-Known Member

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    So, by switching to "Never" and while running on WiFi, what else will "not work" (besides Sprint TV)?
     
  8. imb951

    imb951 Well-Known Member

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    Thanks, I will try this out.
     
  9. deviouskoopa

    deviouskoopa Active Member

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    MMS (pic/video) messages also won't work, as far as I've seen on my phone. Mine just shows a link to download them but that results in an error, and I realized you have to enable 3G to receive/download the MMS.
     
  10. cephraim

    cephraim Well-Known Member

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    Does SMS work over Wifi?
    Or, I should say, does it work when Mobile Data is disabled?
     
  11. scottmbolt

    scottmbolt Well-Known Member

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    Does Visual Voicemail work over WiFi?
     
  12. joshpdavis80

    joshpdavis80 Active Member

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    I learned about this several months ago. I believe it was when I had a samsung moment. The battery was not as good as the hero's. Leaving Wifi on never sleep definitely helps battery life. If you leave your house and are away from a wifi signal for a while, your phone will disable the wifi, I think. The icon at least disappears an will come back on when you get home.
     
  13. Pyr0

    Pyr0 Member

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    to save your battery, Make sure you have good range of Evdo or good range of WIFI. If your range of Evdo is weak, then it will search more towers that give good coverage/strength, that what makes eat battery much. If your WIFI is weak, then it will eat your battery too.
    I use this way all the time. If I see my evdo strength is weak, then I would turn WIFI on to save my battery of course, make sure my wifi strength full. If Evdo strength is full, then don't use or need WIFI, that's best way to save battery.
     
  14. TheBiles

    TheBiles Well-Known Member

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    Thank you SO MUCH! I have a horrible data connection in my apartment, and my university's wireless system requires authentication if you go a while without using it. This way I can save battery AND stay connected to the wireless. :D
     
  15. stinky

    stinky Well-Known Member

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    Tested this out starting this morning, its now time for bed and Im at 40% still, normally Im at 10-20.
     
  16. ignatz

    ignatz Member

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    After a day of testing, this seems to be working for me too. Would not have thought it! Nice tip.
     
  17. cooolone2

    cooolone2 Well-Known Member

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    So the question would be then... what happens to data when outside the WiFi range? If it doesn't switch back to EvDO, You won't have access to data functions? Will it (switch back) if you use a widget or goto settings and turn WiFi off manually?

    I will play with this setting too, sounds interesting.

    Cool find!

    :cool:
     
  18. bilkay

    bilkay Member

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    Thanks for the tip. Just changed the setting.
     

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