Major battery drain on Android 8.1

[Beebock]

Hi,

Noticed a considerable battery drain on my android 8.1. (Nexus 6p).

It takes around 2 hours to tank the battery (80%--> 20%). I have reset etc... to no avail. I'm 6 days away from the end of my trial and don't want to pay for something that I can only use when tethered to the plug, might as well use my sound system as it's sitting right there!

Any advice / feedback would be greatly appreciated

thanks

Richard