random battery drain nvidia shield tablet

[marsh1399]

I am new to android but i am finding it a very good learning experience. I have been experiencing a problem with the battery though and i have no clue what to do. Brief summary; i'll unplug it at 100 percent at night time, and use it in the morning while i am making breakfast watching youtube etc. after a day of school i come home to find it off and have to hold the power button down for an excessively long amount of time and once it's on i have found the battery has drained drastically.

i've included pictures but if they cannot be seen i will describe them:

There is gaps between time used, time that it has been shutoff unexpectedly, and the time i turn it on. gaps appear between the first and second time i turn on while the battery has been drained for no reason. 

 

Please help thank you very much