I have a Nexus 10 whose battery-level estimation seems to be inaccurate: when the battery meter gets to around 10% to 15% remaining, the tablet will abruptly shut itself down the way it's supposed to when it's about to run out of power. Yesterday it happened just a few seconds after I got the 15% warning (asking if I'd like to turn on battery saver); at other times, I get no forewarning at all.
When I plug the tablet in and turn it on again, the battery history graph shows an abrupt drop to 0%. I'm assuming this is a calibration problem: the battery really was close to 0%, but the software thought it was at 15% for some reason. I've read that draining and recharging the battery should recalibrate it and resolve the problem, but this has been happening for nearly a year, and the battery has been drained and recharged many times, yet the problem persists.
The tablet is currently running stock Android 5.1.1, though I think the problem started back when it was running 4.4. It's rooted, but I haven't used root to change any settings that might relate to power management. (I basically just use it for Titanium Backup.)
Is there a way to reset the battery calibration so that the meter is accurate again? Or is it likely to be a hardware problem, caused by something like a sudden voltage drop in the battery itself?
It's worth mentioning that I used to keep the tablet plugged in nearly all the time, before I learned that keeping a Li-ion battery constantly at full charge is bad for it. I've also accidentally drained it completely a few times (not many) even before this problem started. Plus, it's more than 2.5 years old. So the battery is probably not in peak condition. (Its capacity still seems decent overall, though: I'd been watching streaming video for several hours before it shut down at 15% yesterday.)
