What Is Optimal Battery Usage & Lost for iPad? I am using my iPad  Pro about 2.5 years.



If %8 is lost from  iPad Battery in 2.5 years ( March 2016) is this a sign of a bad battery?
According to Apple, you're not bad at all and very much in the healthy range.


https://www.apple.com/batteries/service-and-recycling/



  iPad Owners
  
  
    Your battery is designed to retain up to 80% of its original capacity at 1000 complete charge cycles. The one-year warranty includes service coverage for a defective battery. If it is out of warranty, Apple offers a battery service for $99, plus $6.95 shipping, subject to local tax.