Q: Problems after latest update

Hi. This article may be helpful: https://support.apple.com/en-us/HT203800

As to the battery issue I did not notice any changes yet.

Try to follow the instructions on this page in order to  maximize your battery life: https://www.apple.com/batteries/maximizing-performance/

http://www.idigitaltimes.com/ios-82-battery-life-problems-how-fix-quick-drain-is sues-iphone-ipad-and-ipod-422229

Try to reset your device. This won't delete your data stored on the phone.

• Press and hold the Sleep/Wake button
• Press and hold on the Home button
• Keep holding both buttons until the display turns off and back on with Apple logo on it.

You may also try to reset all settings: go to Settings - General - Reset - Reset All Settings

You may also try to follow these steps:

1. Navigate to settings/general/ battery usage. Check the applications. This will show you which app eats up your battery.

2. Turn off iCloud keychain: Navigate to Settings/ iCloud/Keychain / turn it off.

3. Limit  apps activity on the background: Navigate to Settings/ general/ Background App refresh/ turn it off for each application which uses to much power.

4. Disable auto brightness: Navigate to settings/ display and brightness/ auto-brightness. Turn this option off.

If your phone is under warranty you may also take it to the Apple Store for further diagnostics. Good luck.