New Delhi, Oct. 14 -- A smartphone becomes a lifeline when the lights go out, but keeping it charged is only half the problem. Battery-saving settings can stretch the remaining charge while also changing how alerts and emergency features work.

enable a battery-saving mode, switch off unused wireless connections, reduce screen use and filter nonessential notifications.

The useful distinction is between conserving power and cutting off a way to communicate. A working hotspot, an essential Bluetooth accessory or an emergency alert should not be treated like an unnecessary background task.

1. Use battery-saving mode, but check emergency features

On an iPhone, look for Low Power Mode in the Battery settings. Android phones generally offer ...