Normal lang yan may mga app na working sa background habang naka idle ang cp mo, puede mo itong deactivate by installing wakelock apps.
Abnormal kung mabilis madrain could be leaky na yung battery. By the way ang battery ay nag se self discharge kapag hindi nagagamit ng matagal.
Try this if you want
Use Greenify (Root required)
Hibernate all your apps running on background
Try tweaking your CPU and RAM for maximum battery saving.