A Galaxy S20 loses its battery quickly for a combination of age and settings. The phone's 4,000 mAh battery has been through hundreds of cycles, and the 120 Hz display, Always On Display and 5G radio all add load. Owners on Samsung's community pages report a step change after the upgrade to Android 12 and One UI 4, which they attribute to background activity and a stale cache, and suggest the same remedies: wipe the cache partition, check Settings, Battery for apps with high background use, and restrict them.
Switching the refresh rate from 120 Hz to 60 Hz saves noticeable power, as do turning off Always On Display, lowering the screen timeout and brightness, and turning off 5G where it is weak. If the phone drains quickly even with these changes, the battery has aged and a service is the answer. To judge the battery honestly, open the Samsung Members app and run the battery diagnostic, which reports the battery's status, and compare it with how the phone behaves on a quiet night: a phone that loses more than a few percent between midnight and morning with nothing running has an app or a battery problem, not just a heavy day.
Differential
Likely causes of “Samsung Galaxy S20 family battery drains too quickly”, and how to tell them apart
- 1
The 120 Hz refresh rate
What separates it The screen is the largest user
How to confirm Settings, Display, Motion smoothness: Standard
- 2
Always On Display
What separates it The screen lights with every notification
How to confirm Settings, Lock screen, Always On Display: off
- 3
A weak 5G signal
What separates it The radio is busy in a poor area
How to confirm Use LTE in weak 5G areas
- 4
Background app activity
What separates it One app tops the usage list
How to confirm Settings, Apps, the app, Battery: Restricted
- 5
An aging battery
What separates it Heavy drain with light use
How to confirm Battery service
Before you touch a setting
Record this first — changing settings destroys the evidence
- The refresh rate and Always On Display settings
- The top apps in the battery list
- Whether drain began after an update
- The battery's age
Try in this order
0 of 9 completedSet the refresh rate to Standard
ReversibleSettings, Display, Motion smoothness, Standard, which runs the screen at 60 Hz.
Turn off Always On Display
ReversibleSettings, Lock screen, Always On Display.
Look at battery use
ReversibleSettings, Battery and device care, Battery.
Restrict a heavy app
ReversibleSettings, Apps, the app, Battery, choose Restricted.
Wipe the cache partition
ReversibleFrom recovery mode, after an update, to clear stale data.
Consider a battery service
ReversibleA new battery restores a full day.
Run Samsung's battery diagnostic
ReversibleOpen the Samsung Members app, Get help, Phone diagnostics, Battery status, which reads the battery's condition and flags a failing one.
Do an overnight test
ReversibleCharge to full, turn Wi-Fi on, put the phone down for the night and read the percentage in the morning; a loss above five percent points at a background process.
Check Sleeping apps
ReversibleSettings, Battery and device care, Battery, Background usage limits, and put rarely used apps to sleep.
Model-specific
What is true of this model and not of its siblings
- Age
- A six-year-old battery has lost much of its capacity.
- The refresh rate
- Dropping to 60 Hz is the biggest single saving.
- After upgrades
- A cache wipe clears leftover files after a big update.
- The 5G radio
- The S20 5G models search for 5G constantly in weak areas, so choosing LTE in a poor area can add hours.
- Always On Display
- The feature lights the screen for each notification, which adds up on a busy phone.
- Dark mode
- On an AMOLED screen, dark mode saves power because black pixels are off.
Stop boundary
When this stops being a self-service repair
- !If drain persists after the settings are changed and the cache is wiped, book a battery service
- !If the battery swells, stop using it
- !If the phone shuts off at 20 to 30 percent, the battery is worn
Evidence ledger
Sources behind this answer
Exact questions
Common questions
How long should an S20 battery last?+
A day when new; an old one needs a top-up.
Does 120 Hz drain the battery?+
Yes, noticeably.
Did Android 12 hurt battery life?+
Owners reported it.
Should I replace the battery?+
If settings do not help.
Does dark mode save battery on the S20?+
Yes, on its AMOLED display.
What is Adaptive power saving?+
A mode that limits performance and background use when the battery is low.