Why Is My Phone Battery Draining Overnight? The Checks in Order

Short answer: A healthy phone loses 2-5% overnight with wifi on. If yours loses 10% or more, open Settings > Battery and look at what was active while the screen was off. The three usual causes are weak mobile signal, one app syncing in a loop, or a recently updated app misbehaving.

Overnight drain is a clean test because the phone should be doing almost nothing. Nothing on screen, nothing in your hand, and yet the percentage drops. That makes the culprit easier to find than daytime drain, where everything blends together.

The causes, ordered by how often they are to blame

Charging habits matter too, but they change the battery's lifespan rather than overnight drain. If that is your concern, read how to charge a phone for battery health. For a broader slowdown that includes battery symptoms, how to speed up a slow laptop covers the equivalent diagnosis for computers.

The ten-minute fix routine

1. Charge to 100% before bed and leave the phone untouched overnight.
2. In the morning, open the battery usage screen and sort by background activity.
3. If one app dominates, restrict its background activity or reinstall it.
4. If no app dominates and signal is weak, try aeroplane mode overnight once — a big improvement confirms signal hunting.
5. If nothing helps, check battery health; below 80% capacity the battery itself is the problem.