Phone battery draining fast? Causes and fixes

If your battery used to last all day and now dies by the afternoon, one of five things is usually to blame. Here's how to tell which one.

1. You just updated

After a major system update, phones re-index photos, messages and files in the background. Battery drain for a day or two after an update is normal. Charge it overnight and judge after 48 hours.

2. One app is eating the battery

Open Settings → Battery and look at which apps use the most.

• An app you barely opened near the top of the list is a red flag.
• Update it, restrict its background activity (Android: Settings → Apps → the app → Battery → Restricted), or uninstall it.
• Social, video and navigation apps naturally use more — what matters is whether the numbers match how you use them.

3. Weak signal

When the mobile signal is weak, the phone boosts its radio power to stay connected, which drains the battery fast. If you're in a weak-signal area all day (some offices, basements), switching to Wi-Fi where possible helps a lot.

4. Screen and settings

The screen is the biggest single user of power.

• Turn on auto-brightness and use dark mode on OLED screens.
• Shorten the screen timeout to 30 seconds or 1 minute.
• If your phone has a high refresh rate (90–144 Hz), an "adaptive" or "standard" mode saves power.
• Turn off features you don't use, such as an always-on display.

5. The battery is worn

Lithium-ion batteries lose capacity as they age, mostly with charge cycles, heat and time spent at 100%.

• iPhone: Settings → Battery → Battery Health.
• Android: many phones show health under Settings → Battery, or in the maker's diagnostics app.

Below about 80%, a replacement at an authorised service centre is usually the best-value fix.

Make the new battery (or your current one) last longer

• Avoid heat: don't leave the phone in a hot car or charge it under a pillow.
• Use the built-in charge limit / battery protection option if your phone has one (for example Samsung's battery protection or iPhone's 80% limit on newer models).
• You don't need to drain it to 0% — partial charges are fine for lithium-ion batteries.

Still bad?

If drain stays high after all of the above, back up and factory reset, then set the phone up as new. And if you're wondering whether it's worth keeping, try the Phone Life Check.