Iphone 6 Battery in ios 9.3.3 very bad

Hello Saltymadchicken,

Thanks for using Apple Support Communities.

I see that your iPhone battery is only lasting 2-3 hours. I rely on my iPhone daily, so I know how important it is to make sure that you have a battery that will last a full charge. I'll be more than happy to assist you with this.

Check out the following site for tips to maximize the battery life of your Apple Devices.

Maximizing Battery Life and Lifespan

Additionally, use About the battery usage on your iPhone, iPad, and iPod touch, and learn how to adjust the settings to improve and extend battery life, specifically, these sections:

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.

Best Regards.