Charging Time for Ipad air 2 , 64 GB

That seems a little long to me. I have an iPad Air 2 and it takes bout 4-5 hours to charge from a very low percentage. That is if I am not using it at the time. Are you using the supplied power adapter/charging block? Is this the one and only time that you have charged the device?

It is not normal for an iPad Air 2 to take 7-11 hours. Mine takes roughly 4-4/12 hours when completely drained. You might want to take your iPad to Apple and have them test the battery.