So I have got my Dell Vostro 5490 for a while and recently found out it is possible to change battery charging options. So I download Dell Power Manager and try tweaking. I changed battery settings to Custom 50%-80% and hit restart. And use my laptop normally until I realized it charged to 90%. I was confused and check Power Manager again to find it changed to ExpressCharge instead. I tried changing BIOS also and many times, it just revert to ExpressCharge even though I made sure to apply and save settings. Am I doing anything wrong? Or is there anything wrong with my machine?