XPS 17 9720, battery charge strange behavior

Hello,

I have a new XPS 17 9720 which I use mostly on AC adapter.

I tried to configure the battery settings to custom with 50% and 80% thresholds. I noticed using a wattmeter that this mod prevent the laptop to draw more than 100 W. Then I have battery drain under heavy load. Dell can you fix it? It seems the bug is present for a long time now on previous models also.

I tried primarily AC mod which allows the laptop to draw up to 130W. However the battery seems 100% charged. This mod should not do this : https://www.dell.com/support/manuals/fr-fr/dcpm2.1/userguide_dell-v1/battery-settings?guid=guid-0fbbbeff-4928-4def-89af-3d28d0a231ce&lang=en-us

This thread seems to explain the thing but there is no approved answer and the behavior described seems bad (big drop in battery life when hitting 25%. This can't be ok the the user.)

https://www.dell.com/community/XPS/Primarily-AC-use-What-Does-it-Actually-Do/m-p/8264111

I'd like to have a working mod for primarily AC. Any tips?

Thank you,