My tablet turns off at 40% battery?

[AC Question]

The other day I was watching youtube with my galaxy tablet somewhere around 4-something%. The life was going down at a fair pace, saying this tablet is as old as ****. Then it turned off. When I tried turning it back on, the screen flashed the logo and turned back off. It was acting as if it was out of charge, even though it says it's at 40%
It happened again last night when I was at 50%. I've had problems with this tablet for a long time. I've switched my charger cable before and I just recently updated it.

My tablet is a Samsung Galaxy Tab 4, and I have a software update postponed (if that really means anything) Thank you for helping me if you can!

 

[belodion]

One possibility is a bad battery.

 

[B. Diddy]

Welcome to Android Central! I agree with belodion -- the battery is probably failing. You could try booting into Safe Mode to see if the problem persists: https://support.t-mobile.com/docs/DOC-27814. Also try wiping the cache partition: https://support.t-mobile.com/docs/DOC-27862