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  1. Thread Author  Thread Author    #1  

    Smile Unbelievable battery life with WIFI off -- why?

    Ever since acquiring my S3 on ATT, I've complained about the battery life not being stellar. I've made it to 15 hours before, but have also experienced 6-8 hour drain times. I tried various ROMs and settled on AOKP as my favorite, including a slightly better battery life than the default Touchwiz interface.

    Today, for the first time since buying the phone, I found myself away from WIFI all day, and I turned the WIFI off. The battery life was immensely improved; I am now at 12.5 hours on battery and at 74% battery life, with auto sync turned on, and moderate usage all day. Nothing else has changed, so I have to assume that the WIFI option is affecting the battery life drastically.

    I'm thrilled, but want to know why. I've read on many forums that keeping WIFI turned on should help battery life, since when one is connected to WIFI the phone stops using the radio for data access. Is this incorrect? Is there a way to achieve this long battery life when using WIFI?

    Thanks,
    Jonathan
    SGH-I747, Android 4.2.2, AOKP build 6, Kernel 3.4.37
  2. #2  

    Default Re: Unbelievable battery life with WIFI off -- why?

    Signal strength is at least as important as the connection type. The weaker the signal, the more power your phone pumps into the radio / antenna to try to maintain the connection. If your normal WiFi signal is very weak, but your 3G / 4G signal strong, you may well get better battery life without WiFi. And even when you have WiFi turned on for data, the cellular radio is still on, and still pinging the tower(s) periodically, so if your cellular connection is normally very weak, but much stronger where you were without WiFi, that might have some impact, too.

    If neither of those things are true, I'm at a loss.
    PLEASE, when asking for help provide as much information as possible. We can't help unless we know what the symptoms are and what you did before they began.
  3. #3  

    Default Re: Unbelievable battery life with WIFI off -- why?

    Depends on the signal the better the signal the better the battery life. I can imagine what would happen if you shut off both data and wifi. 35 hours I suppose.
    T.
    Ambassador @ iMore

    "With great power, comes great responsibility." - Uncle Ben
  4. #4  

    Default Re: Unbelievable battery life with WIFI off -- why?

    Well having wifi off ur turning a radio off therefore ull use less batter. No matter what even when ur on wifi you phone is still connected to a mobile network. Lte will use battery more cause the signal is a higher frequency but either way ur phone needs to connect to the network to receive calls and such. Even when not on wifi your phone will still be using both wifi if its on and mobile network. Wether ur signal is weak or strong it wont change. itll use the same amount of power. The signal strength is determind by strength of the incoming network or wifi signal. If u turn off ur mobile data so u cant browse the web just call and text ur battery life will improve drastically because its using a less powerful frequency. Turning it on only when u need it.

    Sent from my SAMSUNG-SGH-I747 using Android Central Forums
  5. #5  

    Default Re: Unbelievable battery life with WIFI off -- why?

    While the above post is almost unintelligible, and also contains numerous errors, it does raise one important point.

    I think we all assumed that when you turned WiFi off you were connected to 3G or 4G data. Is that accurate? If not, and you had cellular data turned off as well as WiFi, that explains it. Having no data turned on will certainly use even less battery than using WiFi, which uses less battery than 3g/4g.
    PLEASE, when asking for help provide as much information as possible. We can't help unless we know what the symptoms are and what you did before they began.
  6. #6  

    Default Re: Unbelievable battery life with WIFI off -- why?

    Sorry it was typed on my phone so there is spelling mistakes. Please fill me in on my errors. If I said something thats not right please show me what is wrong.

    Sent from my SAMSUNG-SGH-I747 using Android Central Forums
  7. #7  

    Default Re: Unbelievable battery life with WIFI off -- why?

    Whether your signal is weak or strong...it'll still use the same amount of power.
    Completely wrong. On both WiFi and Cellular data and voice, with a strong signal the phone will provide the minimum amount of power to the radios possible. As the signal weakens, the phone amps up power to the radios (increases gain in technical terms) to maintain the connection. That uses more battery. A lot more if the signal is very weak.

    Even when not on wifi your phone will still be using both wifi if its on and mobile network
    Not exactly. If you leave the WiFi radio on when there's no WiFi signal, you're phone won't be "using" WiFi. What it will do is poll, looking for a WiFi signal to connect to. Which does use battery power. In fact, since it doesn't detect a WiFi signal at all, the device will increase gain on the WiFi radio to max, using even more power than when you're connected to WiFi.

    Well having wifi off ur turning a radio off therefore ull use less batter.
    Less battery than what? If you have a strong WiFi signal, and turn WiFi on, you'll use less battery than if you turn WiFi off and use cellular data. So if you're using data, turning WiFi off generally causes your phone to use more battery, not less.

    No matter what even when ur on wifi you phone is still connected to a mobile network.
    But not for data. If WiFi is on and connected, the phone uses that for data, and does not connect to the 3G / 4G network, only 1xRTT for voice.
    PLEASE, when asking for help provide as much information as possible. We can't help unless we know what the symptoms are and what you did before they began.
  8. #8  

    Default Re: Unbelievable battery life with WIFI off -- why?

    Quote Originally Posted by meyerweb View Post
    Completely wrong. On both WiFi and Cellular data and voice, with a strong signal the phone will provide the minimum amount of power to the radios possible. As the signal weakens, the phone amps up power to the radios (increases gain in technical terms) to maintain the connection. That uses more battery. A lot more if the signal is very weak.

    Please provide me with technical articles so if I am wrong I know what it is.


    Not exactly. If you leave the WiFi radio on when there's no WiFi signal, you're phone won't be "using" WiFi. What it will do is poll, looking for a WiFi signal to connect to. Which does use battery power. In fact, since it doesn't detect a WiFi signal at all, the device will increase gain on the WiFi radio to max, using even more power than when you're connected to WiFi.

    The radio will still be powerd on and trying to find a wifi network to connect to therefore it still uses battery power compared to it being off.

    Less battery than what? If you have a strong WiFi signal, and turn WiFi on, you'll use less battery than if you turn WiFi off and use cellular data. So if you're using data, turning WiFi off generally causes your phone to use more battery, not less.

    If mobile data is turned off it will use less batter. Same goes for wifi as long as either are not being used turning them iff will save battery consumption.

    But not for data. If WiFi is on and connected, the phone uses that for data, and does not connect to the 3G / 4G network, only 1xRTT for voice.

    Yes true. But in order to get puc messeges it requires mobile data on, but unless you go into the settings and turn off all voice and data radios it will still use the stanard voice radio for talk and text. Turning off data will turn off a higher frequency radio which can save battery leaving the basic radio on. The higher frequency of a radio will use more power.

    If I got anything wrong please provide me with technical articles so I can correct myself from saying wrong information.


    Sent from my SAMSUNG-SGH-I747 using Android Central Forums
  9. #9  

    Default Re: Unbelievable battery life with WIFI off -- why?

    Is it also true that if you have wifi turned on, and you are not in a wifi zone, that the wifi is constantly searching for a waypoint to connect to, and drains your battery? I always get prompts that there are open wifi networks.

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