The reason why the iPad is not charged is mostly because Apple in order to save costs, the ipad is equipped with a 5w charger, charging to 90% of the time, the battery voltage and current have been equivalent to 5w charging flow, so it is no longer charged. In fact, the phenomenon of iPad charging is not often, 90% of the charge can not be used up to 20% and then charged and fully charged. To get a full charge, you need a 12w charger. The ipad charging mechanism must be automatically disconnected from the charge, so with a 12w charger, there will be no problem of charging dissatisfaction. Apple in order to save costs, the ipad with a 5w charger, but I heard that Apple also found 5w charger to charge the ipad has problems, so the new ipad are equipped with 12w charger.