Should I actively turn data off when wifi is on?

[robooneus]

A quick question:

I have always actively gone in to settings to turn cellular data to "off" when I turn wifi on (and actually have a connection). Likewise, I always leave wifi off when I am not specifically connected or about to connect. This I have done in order to save battery.

I have, however, noticed in WP8.1 that when you connect to wifi, the indicator for cellular connectivity no longer shows up. This has made me wonder whether actively turning the cellular data to "off" when I am connected to wifi is even necessary. Is it? Or does connecting to wifi mean that the phone stops looking for/connecting to the cellular data entirely, thus not requiring any extra battery to have the data "on"?

This seems like an obvious thing that the OS should take care of, but things don't always behave in a logical, obvious manner.

Thanks!

 

[wpfan1995]

Yeah I also had same question!
But I don't think that OS turns mobile data(connection) off while wifi is ON as i was downloading an app from store.
Store shows that app is downloading from mobile data rather than on wifi :\
I think Nokia Should look after this Bug in next update(Lumia Cyan)

 

[Kaushik Banerjee]

First preference for internet is alwys WiFi...so if your WiFi is on and connected the mobile data connection wont show up so you don't have to manually turn off data connection. Although you may face issues regarding phone using data even when WiFi is on WP8.1 is preview and the official version will come with fixes.

 

[David P2]

Pulling down the notification centre shows you the what the current mobile data speed is. I'm guessing that in 8.1 it now only shows the current one it's using for a given situation, whereas in 8.0 you had both but if you weren't connected to wifi it just showed the icon as dim.

 

[a5cent]

I have always actively gone in to settings to turn cellular data to "off" when I turn wifi on (and actually have a connection). Likewise, I always leave wifi off when I am not specifically connected or about to connect. This I have done in order to save battery.

Actually, all of that micro management is at best a complete waste of time, and at worst counterproductive. Even under WP8.0 you should always leave both on at all times. WP8.1 didn't change anything about how these work, it's only changed how the current communication state is displayed to you on the screen.

Caveat: that is the theory. I'm not going to claim that this always works perfectly. My point is, the only time you should ever need to do any of that is when a particular device isn't working as it should, be that due to hardware issues, OS malfunctions or poorly programmed apps.

Why?

If you aren't using your device, it's not really active. It's just listening for incoming signals which occurs pretty much for free in terms of power usage. Many people believe they are increasing batter life by turning WiFi off, and on some faulty handsets it actually can, but if everything works as it should, doing so achieves nothing.

Actually, turning WiFi off, while you'd have WiFi access, actually reduces battery life. A few people have gone to great lengths to test this. They all reached the same conclusion. Connecting to the internet is something every WP device does quite frequently, even when it is not in use. Forcing the device to connect over cellular when a WiFi connection is available uses more power! Leave WiFi on and you will use less.

Turning off cellular data saves you absolutely nothing. The radios go into a sleep state and can be remotely woken up from a cell tower. The difference between sleeping radios and turned off radios are, in terms of power draw, completely irrelevant. On the down side, turning radios off will often cause you to receive notifications late, or not at all. A lot of users complain about not receiving notifications on WP in a timely manner, not realizing that they themselves cause this by turning cellular data off.

I'll leave it at that for now.

 

[busyman96]

I don't agree with a5cent. Keeping mobile data on will make the device actively search for a signal. I can confirm that my own device's battery goes down faster with it on, even if I'm not actually downloading anything. Can't speak about Wi-Fi as I always keep that on.

 

[Flavio Lopes]

so tell me when do I have wifi on I get a 9% drain , while when its of it goes to 3~2 !

 

[binnyandrews]

L1520 - WP8.1DP - With 2G data always on, i get a battery of 1.5 days.(36hours) - normal browsing with whatsapp and WPcentral, news reading along with to 1.5 to 2 hours of talk time - battery dries 3.6 - 4% per hour.

With WIFI always on i get 13 hours of battery with the above usage. So far happy with the results.
Note - I have disabled the STORE background in Battery Sense.

 

[a5cent]

I don't agree with a5cent. Keeping mobile data on will make the device actively search for a signal. I can confirm that my own device's battery goes down faster with it on, even if I'm not actually downloading anything. Can't speak about Wi-Fi as I always keep that on.

You might want to reread my post. I did mention a few caveats. You might also want to take a look at the 802.11 standard. It mentions both active and passive AP scans. If you are not using your device, it shouldn't be actively searching for a signal like you claim. Of course I can't guarantee that it isn't, but it shouldn't.

The three devices I have at home all last longer when WiFi is on, so both our claims are anecdotal. As always, any hardware / software revision combination may behave differently, so your mileage may vary. Finally, the standard also mentions some regional differences, in the sense that some regions don't allow WiFi clients to scan actively. I don't know much about that aspect of the standard, but it sounds like it could also result in people making different observations.

The biggest issue one can have is a background process constantly connecting to the internet. This is harder to track with WP8.1 than it is with WP8.0. If you've got something like that your battery life will be dismal.

 

[binnyandrews]

The biggest issue one can have is a background process constantly connecting to the internet. This is harder to track with WP8.1 than it is with WP8.0. If you've got something like that your battery life will be dismal.

This is what i have noticed. The STORE background process consumes more battery. It need to search the store for the data in the background and since the data is huge, it takes longer to update/refresh the Store articles which in turn eat the battery..

 

[gkrew]

I turn data off to ensure that only WiFi is used for app downloads and other connectivity. The only drawback is MMS messages need data to be on to get the media in the messages.

 

[binnyandrews]

Wifi consumes much more battery power than 2G/3G

 

[a5cent]

This is what i have noticed. The STORE background process consumes more battery. It need to search the store for the data in the background and since the data is huge, it takes longer to update/refresh the Store articles which in turn eat the battery..

Yeah. I suspect there is even more stuff like that going on with your device. The reduction of battery life by almost 2/3'rds due to WiFi being turned on is certainly what you are observing, but WiFi itself can't be the cause of that difference. Like I said, my devices actually last longer with WiFi turned on, which just wouldn't work if enabling the technology by itself could noticeably contributed to power draw.

I'm not really ontop of WP8.1 in this regard yet. Based on the fact that WiFi is a hardware feature that involves drivers, I don't think it's worth investing time in any WP8.1 WiFi analysis. I think any such results are pretty much meaningless until we get the entire software package from OEMs, including updated drivers for WP8.1. Based on all the issues people have had with WP8.1 so far, I wouldn't be surprised if there is some funky behaviour in this area as well.

 

[a5cent]

I turn data off to ensure that only WiFi is used for app downloads and other connectivity. The only drawback is MMS messages need data to be on to get the media in the messages.

Completely unnecessary. If WiFi is available it will always be prioritized over cellular for any type of data transfer.

 

[a5cent]

Wifi consumes much more battery power than 2G/3G

Practically every technical document I've read on that issue claims otherwise:



source

 

[herbertsnow]

Completely unnecessary. If WiFi is available it will always be prioritized over cellular for any type of data transfer.

Not always true. I've had a few beta apps that still used cellular even though I had wifi on. Safer to keep it off since I'm on a prepay plan that charges me 10 cents a mb.

 

[MrWhiteman]

No because I always forget to turn it back on after I leave WiFi range and I don't get emails or notifications etc battery loss and data usage will be negligible.

 

[a5cent]

Not always true. I've had a few beta apps that still used cellular even though I had wifi on. Safer to keep it off since I'm on a prepay plan that charges me 10 cents a mb.

EDIT:
Apparently the API would allow for that to occur.

IMHO this is one of those caveats I already mentioned (apps not working as they should). I think carrier apps that access confidential subscriber and network information are the only ones with a valid excuse to prefer a cellular connection. For any other app I'd say such behaviour constitutes a bug. More importantly, if that wasn't a carrier app, I'd say the developer is screwing around with things he/she shouldn't. That seems fishy enough that I'd strongly consider deleting the app. I'd consider the developer completely untrustworthy.

Even if it's just an innocent mistake though, I'd prefer to delete the app than have to micromanage my phone like that.

 

[Blacklac]

Practically every technical document I've read on that issue claims otherwise:

View attachment 66949

source

This. Especially if you have a strong Wifi signal.

 

[AndyCalling]

It is not as simple as always using WiFi when connected. The OS will continue to use 3/4G for some ongoing tasks if it connects to WiFi after the task was initiated, such as if it is in the middle of downloading a file from a server. Also, and this seems new to 8.1, if your WiFi gets confused and drops to 'limited access' (ie. connected to the lan but no internet is getting through, often a trick of public/work/public transport WiFi) the WiFi indicator on the start screen shows no change, and the OS merrily shunts everything over 3G/4G without telling you. Until you check your notification centre you won't be aware that the WiFi isn't working properly and you could rack up quite a bill if you decided to stream something. Still, these are specific situations. Anyone know of any other times this happens?