17 R5, battery draining during gaming, plugged in

After playing highly demanding games for a while my Alienware 17 R5's battery starts to drain while it's plugged in. This is with the 240W adapter that came with the laptop. It seems to drain to either 95% or 90% then doesn't drain further. I found a reddit post (https://www.reddit.com/r/Alienware/comments/8j1jj8/battery_draining_while_plugged_in_when_playing/) where people were claiming that although this is intended, it's still really bad for the battery. Is this true? They claimed getting a 330W adapter fixed their problem. Can anyone confirm this? If I should get a new adapter, how do I go about getting Dell or whoever to approve the new charger so I don't void my warranty? Do I even need to do this? This is the charger I'm looking at: https://www.adaptersdepot.com/dell-ac-adapters-c-122_72/original-330w-dell-alienware-17-r5-p31e-p31e002-charger-ac-adapter-p-185936.html Thanks for the help.