I’m using a Fairphone 5 with e/OS 3.6 stable. Until now, whenever I didn’t need mobile data, for example, at home where Wi-Fi is active, I would turn off the “Mobile Data” feature.
Now, of course, I can have both mobile data and Wi-Fi enabled. Normally, Wi-Fi is prioritized. But how does this work technically? Is “mobile data” actually active, meaning does the device also communicate with the cellular network at certain intervals, or not?
It feels like the device uses more battery when both are enabled; am I mistaken?
I can give an example rather than explanation. I didn’t realise this part at the time but it seems my home router did not have a perfect connection to the exchange, but it managed OK. Two years later the router was replaced by an engineer as part of a job to fix poor landline function.
Meanwhile my first Android phone, /e/OS, was well connected to the router and using Wi-Fi but was switching to mobile data in a random way and generating Mobile data expenses. Seems mobile data was “filling in” but, inconsistently, Wi-Fi was not always playing the dominant part.
Developer options contains Mobile data always active. Once I switched this off my phone behaved well online. There was no issue that mobile data would not jump in appropriately when there was no Wi-Fi.
Once the router was replaced Mobile data always active was not used.
Apart from this example I believe from my experience Wi-Fi to be prioritised.
What I don’t know, in an environment with excellent mobile 5G would this be preferred over certain Wi-Fi? In an environment with imperfect mobile and / or Wi-Fi does the phone waste energy continually searching for best signal?
It depends on the stability of your wifi data connection. When you have an ordinary wifi environment (not the one from the neighbors in the 3rd floor …) the mobile data connection can consequently be switched off. This saves a lot of energy because keeping the mobile connection alive (over a distance of a km to the next antenna) costs much more energy than to the next wifi router.
With both enabled, the phone normally uses Wi-Fi for internet traffic when a usable Wi-Fi connection is available. Mobile data stays available as a fallback, but that doesn’t mean your apps are constantly sending data over the cellular connection. The modem still has to maintain a connection with the mobile network for calls, SMS and network registration, so turning mobile data off doesn’t completely shut down cellular activity anyway. Any extra battery use from leaving mobile data enabled is usually small, although it can be more noticeable in areas with weak cellular coverage. So at home with good Wi-Fi, just leave mobile data enabled unless you’re specifically trying to save battery or prevent cellular data from being used.
I keep both on, decided to select prioritise mobile network for calls, wi-fi as secondary, but my phone GS6 Pro still chooses to do wi-fi calls as first channel choice regardless…
Perhaps with VOI connection it always uses the best internet channel available.
Thanks for all the replies. I’ve been experimenting a lot with this, too. I’m sticking to my approach: when Wi-Fi is on, turn off mobile data. That saves battery time.
Another thing that works really well is turning on Flight Mode + Wi-Fi. That’s how the battery works the longest.
