My iPad Air 2 is just over two years old. I do use it a lot and would charge it every night. It's now needing a charge earlier in the day. Is there possibly anything running in the background that needs to be shut down? Is there anything like Control Alt Delete to end tasks?
As to 'quitting' an active app, use the
Multi-tasking Screen by double pressing the HOME button - suspended apps (and there will be MANY) are displayed; by pressing and flicking up, the app is closed.
Apple has plenty of KB articles discussing lithium ion battery technology - just one
HERE - some of the suggestions may help; also, Apple recommends that about once a month, the battery should be near completely discharged (< 10%, BUT NOT ALL THE WAY!), then charged overnight - this will recalibrate the battery monitoring technology, and hopefully improved its endurance.
Finally (depending on whether you have a computer), download
Coconut Battery - plug in your iPad, run the app, and select the 'iOS Device' tab - see attachment below of my wife's Mini - the 'battery health' is 90% (simply the current capacity, i.e. 4521 mAh, divided by the manufactured capacity, i.e. 5018 mAh); another important number is the 'Loadcycles', now @ 401 - in general, at 500 or so cycles, the battery should maintained about 90% of its original capacity - SO, if you can post a similar pic or provide the numbers mentioned. Dave
.