samsung gallaxy Tab 3 a year and 1/2 old. recently I have had excessive battery drain

[AC Question]

going form 100 pct to drained in under 1 hour not running any applications at all. i do not have an SD card in it. in the settings it shows the Android OS consuming 84% of my battery

 

[Rukbat]

If you normally drain the battery down past 50% before charging it, it's probably at end of life. (Lithium batteries can't take deep discharge.) 18 months of that kind of abuse means that you had a pretty tough battery - I've seen them fail in a few months. Keep it at 40% or above and it'll last for years. (I have one that's a bit over 11 years old, and it's still good. It's a plain old flip phone, but if I pop my SIM card into it, I can get at least a day on the battery with a lot of calls.)

The consumption percentage is of the total amount consumed - so 84% could be 84% of the 5% consumed, which would be extremely light consumption - only 4.2% of the battery power.

Then again, it could be a rogue app. Start in safe mode.

Power the tablet completely off.

Press and hold the “Power” button to turn the Tab 3 back on.

When the Galaxy Tab 3 logo appears on the screen, press and hold the “Volume Up” button.

Continue to hold the “Volume Up” button until the tablet completely starts. You’ll see the words “Safe Mode” in the lower-left corner of the screen.

If it still drains like that, it's probably the battery. If not, run one of the apps you normally run at a time, watching for excess drain.