Before posting here, please try the following:
Settings / Look and Feel / Player UI / Chromecast Button - Disable (+ restart Poweramp by dropping it from recents when it's not playing)
This helps with some un-updated/failing Play services libraries being loaded into Poweramp and increasing battery usage.
Settings / Library / Scanner / Auto-scan - Disable
This helps with some apps constantly/frequently sending file system change event causing Poweramp to rescan frequently and increasing battery usage.