iphone 6 plus battery life

Hello there, Radel.

It sounds like you're having issues with unusual battery drain on your iPhone 6s. The following Knowledge Base article offers up some great steps to review to troubleshoot your issue:

About the battery usage on your iPhone, iPad, and iPod touch

Check battery usage

Go to Settings > Battery. To see how long each app has been open and onscreen, and running in the background, tap . Under each app, you might see these usage types: Background Activity means that your battery is used while apps run in the background. Audio means that apps play audio while running in the background. No Cell Coverage and Low Signal means that your device is searching for a signal or being used with a low signal. Backup & Restore indicates that your device has been backing up to iCloud or restoring from an iCloud backup. Location and Background Location means that your battery was used when tracking your device.

Adjust settings to improve battery life

While viewing your battery usage, you might get a suggestion like Enable Auto-Brightness or Adjust Display Brightness. This is because iOS determined that changing these settings could improve your battery life. You can also see the usage times since the last full charge.

Use Low Power Mode

If you want to extend your battery life, turn on low power mode. This reduces power consumption until you turn it off or charge your iPhone to 80%. When low power mode is on, certain settings and features like mail fetch, Hey Siri, Background App Refresh, and some visual effects are reduced or disabled.

Learn more about low power mode.

There are some additional pointer in this article as well:

Batteries - Maximizing Performance - Tips for iPhone, iPad and iPod touch

Thanks for being a part of Apple Support Communities.

Cheers.

My wife and I have two iPhone 6 Plus, almost exactly two years old. The battery of her phone lasts until the afternoon only since some weeks ago. Mine lasts two days still. We visited Apple Store Support twice and they say that the battery is still right, 87% of original capacity, and only suggest changes in application settings, factory reset and reinstall of apps, etc. which hasn't solved the problem. Yesterday we exchanged our phones (fresh install for her and restore from backup for me) to see if apps and habits were culprit and now her phone, which was mine, lasts two days and mine, which was her, lasts until the afternoon only. So, it is a battery or hardware problem, not solvable through settings. I will change the battery in our third visit to the Apple Store in the next days.