Venue 8 Pro Power Problem...Hibernate?

Several days can pass between the times when I use this tablet, and more often than not, the battery will be dead.  (And it won't boot once it's plug in -- must wait until the battery gets some recharge.)

The solution seems simple: set the tablet to hibernate or completely power after some period of being idle.  But I cannot find any setting to do this, only for it to go to sleep -- which continues draining power until it is dead.

Windows settings on my desktop/laptop will set it to sleep for X minutes, and then if un-used for another X minutes, it will power down or hibernate.

How can I do this w/ the Venue 8 Pro?  (And if it can't do one followed by the other, I would prefer it just hibernate or shut down.)

Thanks for any advice or help!