Your Xiaomi 15's battery is a powerhouse, but like any lithium-ion cell, it slowly loses capacity over time. Checking its health helps you understand its current state and plan your charging habits to get the most life out of it.
Find Battery Health in HyperOS Settings
Xiaomi's HyperOS 2 includes a built-in battery health checker. Open Settings and tap on Battery. Scroll down and look for the Battery health section. Here, you'll see your battery's current maximum capacity displayed as a percentage compared to its original design capacity.
This menu also shows the estimated battery life based on your current usage patterns. If you're not seeing the health percentage, make sure your phone is updated to the latest version of HyperOS, as this feature was refined in later updates.
Monitor App Battery Drain
To see what's actually using your power, go to Settings > Battery > Battery usage. This screen breaks down consumption by app since your last full charge. Tap on any app to see a detailed split between foreground and background activity.
This is especially useful on the Xiaomi 15, as the powerful Snapdragon 8 Elite chip can sometimes let background processes run a bit hot. If you see a system app or game using an unusual amount of power here, you can manage its permissions directly from this screen.
Use AccuBattery for Detailed Metrics
For a deeper, long-term analysis, I'd recommend installing AccuBattery from the Google Play Store. This app runs in the background and tracks every charge cycle. After a few days, it provides a very accurate estimate of your actual battery capacity in milliamp-hours (mAh).
It also shows your charging speed, so you can verify you're getting the full 90W from your HyperCharge adapter. The health percentage it provides often aligns closely with the system reading, giving you a good second opinion.
Check for Hidden Diagnostic Info
Android has a hidden testing menu you can sometimes access. Open your Phone app and dial *#*#4636#*#*. If it works on your Xiaomi 15, it will open a menu. Select Battery information from the list.
This screen shows technical data like battery voltage, temperature, and health status. It's a bit more raw than the user-friendly settings page, but it can confirm the basic health reading you see elsewhere.
Optimize Battery with HyperOS Features
Head back to Settings > Battery. Look for the Battery saver and Performance modes. For daily use, the balanced mode is fine. Enabling Game Turbo from the Game Center can actually improve efficiency during gaming by optimizing system resources, preventing the chip from overheating and wasting power.
Also, dive into Settings > Apps > Manage apps to restrict background activity for apps that don't need to constantly update. This is a more manual but effective way to stop unnecessary drain.
Enable Smart Charging Protection
Xiaomi includes a feature to help preserve long-term battery health. In Settings > Battery, look for an option called Smart charging protection or Optimized charging. Turn this on.
When enabled, your phone learns your sleep schedule and will slow down charging past 80% overnight, only topping up to 100% right before you typically wake up. This reduces the time the battery spends at full voltage, which is the single best thing you can do to slow degradation.
Recognize When a Replacement is Needed
If your Battery Health percentage drops below 80%, you'll likely notice it not lasting a full day anymore. Other clear signs include the phone shutting down unexpectedly with 20% or more charge left, taking an excessively long time to charge even with the 90W brick, or in rare cases, the back casing feeling warm or bulging when the phone is idle.
At that point, the battery has significantly degraded. You should contact Xiaomi support or an authorized service center for a replacement, as the Xiaomi 15 uses a sealed battery that requires professional tools to change safely.
Daily Habits to Extend Battery Life
Heat is the biggest enemy. Try not to use your phone for intensive tasks like gaming while it's fast charging, as this combines two heat-generating activities. If you're using the 50W wireless charger, I'd recommend taking the case off to improve heat dissipation.
Using the official 90W HyperCharge adapter or a certified high-wattage USB-C PD charger is best. Cheap, uncertified chargers can cause inconsistent power delivery that stresses the battery. Also, consider disabling system ads by going to Settings > Passwords & Security > Privacy > Special permissions > Show on lock screen and toggling off recommendations, as these background fetches use small amounts of power constantly.