If your Xiaomi 15 charges only up to 80% or fails to charge fully, it is because the battery protection or smart charging feature is enabled. These features are designed to extend the lifespan of your battery by preventing it from charging to its maximum capacity regularly, which can help reduce wear and tear over time.
To resolve this, you can turn off this feature by the following steps:
1. Go to [Settings];
2. Enter [Battery];
3. Select [Battery protection];
4. Disable the [Smart charging] or [Battery protection] option.
Once disabled, your device will be able to charge to 100%. Please note that this battery protection feature is not a malfunction. It’s implemented to protect and optimize the overall health of your battery in the long run. Feel free to continue using your device with confidence.