This happens to me too. I always do a shut down when done using the device because of all I have heard about the sleep problems. I left it shut down in the basement after using about 40% total power and when I went down to get it about a day, day and half later the batteries were at 0%.
I just want to add I have the i5/8GB/Dgpu. This unit is about a week old, and is a replacement of my last unit.
I have done all updates, I have not touched any power settings.
My normal routine is to use it at night, I've used it every night since I bought it, and then in the morning put it on the charger. I have not turned on in the AM to take note of any % drop, but I may now.
Of more interest is that I had to replace my last one due to main battery at 0% and not charging. I think I may have left it off charge for a few days at that time too, but didn't think anything of it.
Both batteries were at 0% this time but after a 2 hours or so last night were almost fully charged.
I will pay more attention to shut down at night levels and morning levels. I'll post my results.
If detaching works better I will try that as over the weekends it's highly likely I don't get it on a charger all the time. I don't want to fear discharging a battery.
I hope the Jan patches fix this.