Thank you for engaging, and for your suggestions. I have owned the machine from new, for a little more than a year. It was manufactured approximately 4 months prior to the date, it came into my possession. The laptop was displaying the problem described, from the outset.

I am in full agreement with your assessment on ageing devices exhibiting the Bathtub Curve, and also your suggestion on undercharging. However, the battery on this device has less than 15 cycles in total. Furthermore, when in Sleep mode, it only loses 2-3% daily from its designed capacity -- which is an acceptable range.

Hence, the reason for my curiosity to determine the precipitous drop in charge, when the machine is in a complete shutdown state. You are correct, there are a lot of features in the latest BIOS for management i.e. CPU, power, network, battery etc. I have disabled most of them or opted for the best possible option, where appropriate.

The point about the battery is moot, as I am more concerned about an undocumented feature which might be causing the high drain. There are more reports of Dell laptops exhibiting this unsolvable behaviour, than any other manufacturers combined ─ which usually relate to Modern Standby and/or Intel Management Engine(IME).