Problem solved after updating the BIOS and setting the power configuration as "Custom: starting at 50% and stopping at 80%". Thank you very much!
My Alienware m15 R7, brand new, with just the OEM apps, with no workload, plugged on AC, is charging and discharging a lot. I've read about Hybrid Power, which is used when there is a heavy workload, but this is not the case. As you can see on the battery report below, it switches from battery to AC a lot. As the workload is light (just the OS), shouldn't the battery not be used or at least last longer as AC is being used? [IMAGE]  
m15 R7, battery charge, discharge every 20 seconds on AC no load