I have noticed that the battery seems to run down by itself when I do not use the tablet for several days. After a bit of thought, the solution seems obvious. With a SSD drive, the hibernating the system only takes a few seconds longer than sleeping it.
In sleep mode the system state is stored in RAM and the computer remains powered on (albeit with much lower power consumption). Your battery will gradually drain. If you use and charge the computer every day, you do not notice this power loss.
In Hibernation mode, the system state is written out to the hard drive and the power is turned off. The speed of the Solid State Drive is fast enough that you do not notice the extra time that it takes to write and read this info from the disk.
