Quick answer
You check iPhone battery health in `Settings > Battery > Battery Health & Charging`. If maximum capacity is below 80% or it says "Service", the battery has degraded and should be replaced. Otherwise, fast draining is usually caused by apps, settings or an outdated iOS.
How to recognize the problem
- Battery drops below 20% by noon
- Phone gets noticeably warm during use
- Battery percentage jumps suddenly (e.g. from 40% to 15%)
- iPhone shuts down by itself even though it shows charge
- Charging takes longer than before
Most common causes
Worn-out battery
Lithium-ion batteries lose capacity over time. After 500 to 1000 charging cycles, maximum capacity can drop below 80%, so the phone drains faster.
Power-hungry apps
Navigation, social media, games or apps running in the background can significantly drain the battery, especially if they are allowed to update location in the background.
Battery-draining settings
High screen brightness, always-on location services, Bluetooth or background app refresh increase power consumption.
Outdated or faulty iOS
Updates bring power optimizations. If iOS is outdated or the installation was incomplete, the battery may drain faster.
Poor network signal
When signal is weak, iPhone boosts antenna power to maintain connection, which drains the battery further.
Step-by-step fix
- 1
Check battery health
Open
Settings > Battery > Battery Health & Charging. On iPhone models with iOS 11.3 or later, you will see the maximum capacity percentage and a status message. If it says "Service", the battery has degraded and replacement is recommended. - 2
See which apps use the battery
In
Settings > Battery, review the battery usage list by app for the last 24 hours or 10 days. Pay attention to apps at the top that you rarely use. Tap an app to see how much it used in the background. - 3
Limit background app refresh
Go to
Settings > General > Background App Refreshand turn it off for apps that do not need to be always active. You can turn it off completely or leave it on only for apps you use (e.g. Mail, Calendar). - 4
Lower brightness and enable automatic
Open
Settings > Display & Brightnessand turn onAutomatic. Manually lower brightness with the slider. On the same screen, you can turn onDark Mode, which uses slightly less power on models with OLED screens, and inSettings > Accessibility > Display & Text Sizeyou can enable the reduce white point option. - 5
Turn off unnecessary location services
In
Settings > Privacy & Security > Location Services, review which apps use location. For most, chooseNeverorWhile Using the App. AvoidAlwaysexcept for navigation and similar apps. - 6
Update iOS
Check if an update is available in
Settings > General > Software Update. Install the latest iOS version. If the update is already installed, check that it completed. - 7
Calibrate the battery
Once every few months, let the battery drop to a low level (around 10%), then charge it to 100% without interruption. This helps the system show the percentage more accurately, but does not extend battery life. Avoid fully draining until shutdown, because lithium-ion batteries do not like deep discharge.
- 8
Check if the phone is overheating
If the iPhone feels hot, remove the case and stop charging it until it cools down. Overheating speeds up draining and damages the battery. Avoid direct sunlight and leaving it in a car.
If nothing helps
If maximum capacity is below 80% or it says "Service", battery replacement is the most effective solution. Contact an authorized service center or Apple Support. Do not try to replace the battery yourself, as this can damage the device and void the warranty. If capacity is above 80% and the phone still drains fast, check if it is a software issue: make a backup, then try resetting all settings (Settings > General > Transfer or Reset iPhone > Reset > Reset All Settings). This does not erase data, but restores network and other settings to factory defaults, so saved Wi-Fi passwords and cards in Apple Wallet will be removed and you will need to re-enter them. If that does not help either, a hardware fault requiring diagnostics is possible.
How to prevent it
- Avoid fully draining the battery; charge it when it drops to 20-30%.
- Do not leave the phone at high temperatures or in direct sunlight.
- Use original or certified chargers and cables.
- Regularly update iOS and apps.
When to call a professional
If the phone is under warranty or maximum capacity is below 80%, contact an authorized service center or IT support to check if battery replacement is needed and if the fault is hardware-related.
IT infrastructure maintenance · Servers, networks, backup, security and helpdeskFAQ
How often should I check battery health?
Once every few months is enough, or when you notice the battery draining faster. If the maximum capacity percentage is approaching 80%, check more often.
Does battery replacement erase data?
No, battery replacement does not affect data. However, before service, make a backup via iCloud or computer, just in case.
Why does my phone show 100% and then suddenly drop?
This can be a sign that the battery has degraded or that the percentage is not calculated accurately. Let the battery drop to around 10% and charge it to 100% without interruption, then check if the percentage has stabilized.