fully charged ipad mini, then it drains completely without use
the first time it happened, i took it to the Apple Store and they ran a diagnostic, everything seemed fine and i was sent on my way. it happened several times after and twice in this past week. before i took my ipad off the charger this morning, i saw that it was fully charged. time to use it later in the day, the ipad had shut down completely and prompted me to charge it. what gives?
ps. my firmware is up-to-date and i usually charge when it's 20-30%.