When you use your mobile data instead of a WiFi network, your phone’s battery drains faster. This isn’t an Android specific thing. It also happens on iPhones, and any other portable device that can connect to a mobile network. Most people keep their mobile data off until they have to go outside and know they won’t be connected to a WiFi network. If you keep your mobile data on in case your WiFi isn’t working, your battery drains much faster. Android has a built-in feature that lets you automatically disable mobile data on WiFi.
This feature is kind of hidden. It’s only available if you have Developer options enabled.
Enable Developer Options
You need to first enable developer options. Open the Settings app and go to the About Phone section. On some phones, you might have an About device section. Under this section, you need to find the Build number or the Build Information.
Tap the build number seven times and it will enable Developer options.
Disable mobile data on WiFi
Now that you have developer options enabled, open the Settings app and tap Developer Options. Developer Options might be nested under another set of settings. Once you’re on the Developer options screen, scroll down to the Networking group of settings, and turn the ‘Mobile data always active’ option off.
With this option turned off, your device’s mobile data will be turned off when it’s connected to a WiFi network. When your device loses connectivity to a WiFi network, whether it’s because the router has been turned off, the network isn’t working, or you’ve left a WiFi network’s range, mobile data will be turned back on.
When your phone’s battery is low, and you can’t get to a charging point, turning the mobile data off will help it last longer. The difference it makes can be quite a bit. If you’re looking to extend how much use you get out of a single charge, you can also enable low battery mode but doing so will not turn off mobile data. It’s something you have to manually turn off.
iOS has something similar called WiFi Assist though if you want to disable it, you don’t need to enable any special settings. Remember that it’s ‘similar’, not exact. What the feature on iOS does is that it prevents your device from using your cellular data when the WiFi network signal is weak. It doesn’t turn cellular data off. It can prevent your cellular data from being used unnecessarily but it won’t help your battery last longer.