The battery on my Samsung tablet, SM-T320, has suddenly started fully discharging in about 15min, it also now rapidly charges to 100%.

How old is it? When my S3 went wrong after about 22 months Samsung tested the phone, replaced the battery and updated it under the handsets 2 year warranty. I don't know if there's something similar on tablets.

Funnily enough I switched it on and off and it's behaved OK ~ don't normally switch it off.