Please save my phone battery

Hello tamim786,

Welcome to Apple Communities, please note that I do not work for Apple, and my answer is based on what I know.

There are multiple ways that you can preserve how long your battery lasts on your iPhone. You can turn on low power mode, disable Bluetooth/WiFi/AirDrop/Cellular Data if you are not using them, or/and disable background app refresh. If the battery is dying too fast, you may have to check your battery's maximum capacity. But before doing any of this, you should check out the attached link.

This link might also be helpful to you:

iPhone Battery and Performance - Apple Support

Is it in danger? The only way to keep your battery health at 100% is to never use the battery.