Phone battery draining fast? What to check first

Before anything else, open Settings, then Battery, and look at which apps used the most power since the last full charge. One app running in the background causes most sudden drains.

Then check these, in order:

• A recent system update. Phones often re-index photos and apps for a day or two after one, and the drain settles by itself.
• Screen brightness and refresh rate. High refresh rate and full brightness cost the most battery.
• Weak signal. A phone hunting for network in a basement or lift drains quickly.
• Location and Bluetooth scanning, which keep the phone awake even when Wi-Fi and Bluetooth are off.

If the drain started suddenly and none of this helps, post your phone model, software version and what the battery screen shows, and someone will help narrow it down.