This kind of issue is often caused because an antivirus product has been uninstalled and not properly uninstalled, leaving files in the System folder. AVG Cleaner Pro scans your device's memory and storage space to remove unused files that clog up your Android system and slow it down, causing your battery to drain faster than usual. Therefore when AVG Cleaner Pro is uninstalled these left-overs are not removed properly by the operating system; this will cause the original issue again (battery life reduced). To resolve this problem you can uninstall AVG Cleaner Pro completely or do a clean install.