Generally when doing an operating system upgrade, I've had much better luck doing a factory reset.
Clearing the cache can sometimes help with odd stuff after an upgrade (power down, press and hold (POWER - HOME - VOLUME-UP), release when the phone shows "recovery starting", press VOUME-UP when you see the Android with the spinning thing in his belly, select [CLEAR CACHE] a couple of times, and then select RESTART)
Barring either of those, simply using the phone should allow the new OS and the battery to "get to know" each other, and it should clear up in a few battery cycles.
02-10-2016 10:51 AM