Quick answer: Most fast battery drain comes from four things: the screen (brightness and how long it is on), apps running in the background, a weak cellular signal, and a worn-out battery. Check which apps use the most power in Settings > Battery, lower brightness, limit background activity and update your software. If battery health is around 80% or lower, or the phone drains fast even when you are not using it, the battery needs replacing. Our phone repair shop in Eagan tests batteries for free and replaces most in under an hour.
Key takeaways
- Start with Settings > Battery on any phone. It shows exactly which apps are using the power.
- The screen is the biggest battery user on every phone. Brightness, a 120Hz display and Always On Display all add up.
- A weak signal (basements, rural roads, some office buildings) can drain a phone faster than heavy use.
- Batteries wear out. At about 80% health, or around 500 charge cycles on older iPhones and many Android phones, drain gets noticeably worse.
- Fast drain right after a big software update is common and often settles down within a few days.
In this guide
Step 1: Find Out What Is Using Your Battery
Before changing any settings, look at the battery usage screen. It tells you whether one app is the problem or whether the drain is spread across everything, which usually points to the screen, the signal or the battery itself.
If one app is using far more than the others (a social app, a game, a navigation app or a video app), start there: close it, update it, restrict its background activity or reinstall it. If “Screen” or “Display” is at the top, brightness and screen-on time are the cause. If “Mobile network standby” or “No cell coverage” shows up high on Android, or the phone gets warm in your pocket, the signal is the likely cause.
12 Reasons Your Battery Drains Fast (and the Fix for Each)
| Cause | Why it drains the battery | Fix |
|---|---|---|
| 1. High screen brightness | The display is the single biggest power user | Turn on auto or adaptive brightness and lower it indoors |
| 2. Long screen timeout | The screen stays on after you stop using it | Set the screen to turn off after 30 seconds to 1 minute |
| 3. 120Hz refresh rate | Smoother scrolling uses more power | Samsung: Settings > Display > Motion smoothness > Standard. Pixel: Settings > Display > Smooth Display off |
| 4. Always On Display | The screen never fully turns off | Turn it off or set it to show only when tapped |
| 5. Background app activity | Apps refresh, sync and track location while closed | Restrict background use (iPhone: Background App Refresh; Samsung: Background usage limits; Pixel: App battery usage) |
| 6. Location services | GPS is power-hungry | Set apps to use location only “While using the app” |
| 7. Weak cellular signal | The phone boosts its radio to stay connected | Use Wi-Fi calling indoors; turn on Airplane Mode where there is no signal |
| 8. Push email and notifications | The phone wakes up constantly | Turn off notifications you do not need; fetch email less often |
| 9. Bluetooth, hotspot and NFC left on | Radios searching and staying connected | Turn off hotspot when done; remove Bluetooth devices you no longer use |
| 10. Heat | Hot batteries drain faster and wear out quicker | Keep it out of the sun and take the case off while charging. See why is my phone hot |
| 11. Outdated software or a buggy app | Bugs can keep the processor busy | Update the phone and your apps |
| 12. A worn or damaged battery | Less capacity means shorter battery life | Check battery health; replace it at about 80% |
Battery Drain After a Software Update
It is normal for a phone to drain faster for a day or two after a major iOS or Android update. The phone reindexes photos and files, rebuilds app caches and optimizes apps in the background. Leave it plugged in overnight on Wi-Fi to let that finish. If the drain continues for more than about a week, check battery usage for a misbehaving app, update all your apps, and restart the phone. Samsung users sometimes report heavy drain after One UI updates; Samsung’s own advice is to update apps, use Device care to optimize the phone, and restart.
Samsung Galaxy Battery Fixes
- Settings > Device care > Optimize now. Closes background apps and clears clutter.
- Settings > Battery > Background usage limits. Turn on “Put unused apps to sleep”, and add apps you rarely use to “Deep sleeping apps”.
- Settings > Battery > Power saving. Turn it on when you need the battery to last.
- Settings > Display > Motion smoothness > Standard (60Hz instead of 120Hz), plus Dark mode.
- Settings > Lock screen and AOD. Turn off Always On Display or set it to Tap to show.
- Test in Safe Mode. If the battery lasts much longer in Safe Mode, a downloaded app is the cause.
Galaxy battery replacement at our Eagan shop costs $142 to $147 for the S20 to S25 series. See our Samsung battery replacement cost guide and Samsung repair in Eagan.
Google Pixel Battery Fixes
- Settings > Battery > Battery usage. Find the app using the most.
- Turn on Adaptive Battery (Settings > Battery > Adaptive preferences), which limits apps you rarely use.
- Turn off Smooth Display to drop to 60Hz, and use Dark theme.
- Use Battery Saver or Extreme Battery Saver when you need the phone to last.
- Check Settings > Battery > Battery health on models that show it.
We repair Pixel phones at our Eagan shop; see Google Pixel repair in Eagan.
iPhone Battery Fixes
- Settings > Battery. See which apps use the most over 24 hours and 10 days.
- Low Power Mode (Settings > Battery) reduces background activity and visual effects.
- Background App Refresh (Settings > General > Background App Refresh). Turn it off for apps that do not need it.
- Location Services (Settings > Privacy & Security > Location Services). Set apps to “While Using”.
- Check Battery Health. Here is how to check iPhone battery health.
For every iPhone repair, including same-day batteries, see our iPhone repair in Eagan page.
Is It the Battery Itself?
If you have tried the fixes above and the phone still drains fast, the battery is probably worn. Signs include:
- Battery health at about 80% or lower (iPhone: Settings > Battery > Battery Health; many Samsung and Pixel phones show it in Settings > Battery, and the Samsung Members app can test it).
- The percentage drops in big jumps, for example from 30% to 5%.
- The phone shuts off with charge left, especially in the cold. See why your phone dies in the cold.
- The phone gets hot while charging or during light use.
- The back bulges or the screen lifts from the frame. Stop charging it and bring it in.
A new battery is usually the cheapest way to make a two to four year old phone feel new again.
Battery Replacement Prices in Eagan
| Phone | Battery replacement at Helpertech Eagan |
|---|---|
| Samsung Galaxy S20 and S21 series | $142 |
| Samsung Galaxy S22 to S25 series | $147 |
| iPhone XS, XR, 11 series | $100 |
| iPhone 12 and 13 series | $120 |
| iPhone 14 and 15 series | $130 |
| iPhone 16 series | $150 |
| iPhone 17 series | $175 |
| Google Pixel and other Android phones | Call 651-427-9087 for a quote |
Prices are from our repair pricing page. Every battery replacement includes a free battery test beforehand and a 90-day warranty afterwards, and your data stays on the phone.
Related phone repair guides
Frequently Asked Questions
Why is my phone battery suddenly draining so fast?
The most common causes of sudden drain are a recent software update, an app misbehaving in the background, a weak cellular signal, or heat. Check Settings > Battery to see which app is using the most power, update your apps, and restart the phone. If it continues for more than a week, test the battery.
What drains a phone battery the most?
The screen. High brightness, long screen-on time, 120Hz refresh rates and Always On Display use the most power. After that come background apps, GPS, a weak signal, and hotspot or Bluetooth left on.
Is it normal for my battery to drain after an update?
Yes, for a day or two. After a major update the phone reindexes files and optimizes apps in the background. Leave it on the charger overnight on Wi-Fi. If the drain lasts longer than about a week, look for an app that is using unusual amounts of battery.
How do I know if my phone battery needs replacing?
Replace it if battery health is around 80% or lower, the percentage drops in big jumps, the phone shuts down with charge left, it gets hot during normal use, or the battery is swelling. A repair shop can test the battery for free.
How much does a phone battery replacement cost in Eagan?
At Helpertech in Eagan, Samsung Galaxy S20 to S25 batteries cost $142 to $147, and iPhone batteries cost $100 to $175 depending on the model. Most battery replacements take under an hour and come with a 90-day warranty.
Does dark mode save battery?
Yes, on phones with OLED screens, which includes most Samsung Galaxy, Google Pixel and iPhone models from the last several years. Dark pixels on an OLED screen use less power, so dark mode can noticeably extend battery life.
Battery Still Draining Fast? Get a Free Battery Test in Eagan
Bring your Samsung, Pixel, iPhone or other phone to Helpertech at 2040 Cliff Rd #103, Eagan, MN 55122. We test the battery for free, tell you whether it is the battery or a setting, and most battery replacements take under an hour with a 90-day warranty.
About the author: This guide was written by the Helpertech repair team, the technicians at our Eagan phone repair shop at 2040 Cliff Rd #103. Helpertech has been repairing phones, tablets and computers in the Twin Cities since 1995. Prices were checked against our repair pricing page in September 2026.
