Hi [NAME] the m15 series of laptops have Hybrid Power Design, power is drawn from ac adapter and battery during heavy loading. Battery discharge is an expected behavior of hybrid design on the Alienware m15 systems to maintain full system performance under extreme heavy loading conditions.  If you continue to have concerns about battery status, it should be removed for visual inspection. Then decide if laptop should have an internal battery. Seemingly a Desktop would be more agreeable to alleviate your concerns. 
When I use my m15 R5, at the left side of my palmrest, it starts getting hot when I run it on battery. I am starting to get scared. Dell support said to replace fans and heatsink, which I think is the very wrongest thing to do. Is it supposed to get hot? I checked Jarrod's tech's review and it looked normal.
m15 R5, left side palmrest getting hot, is it normal?