Why is the battery percentage dropping while time remaining increases?

[AC Question]

Samsung Galaxy Tab 3 - Battery percentage is dropping 2-3% every minute, but the amount of time on the battery increases. Tablet winds up running at 1% until the battery is finally drained. Screen is dimmed because of battery percentage.

I have already tried removing the microSD card and restoring factory settings.

 

[B. Diddy]

Welcome to Android Central! Time remaining is an estimate. If you're just watching the battery menu, the time remaining will probably increase, since you're not doing anything else. But if you were to use the phone in a normal fashion, the time remaining would probably fall appropriately.

How old is the tablet? Do you routinely let it drop to single digits before recharging? That kind of behavior can shorten the battery's overall lifespan--lithium batteries don't like regular deep discharges.