I have an I-Pad Air 2 approx. 11 months old with battery problems. The battery lasts approx. 4 hours. I erased all content and settings and now the battery lasts considerably longer, however once the battery is fully charged and starts to discharge through usage, the "time since last charge showing usage and standby disappears after a couple of hours and is replaced by 2 dashes. Also has the low power mode disappeared after I loaded the latest software IOS 10.1.1 .Its on my I-phone but not the iPad, is this correct. Also how long should the battery last, I don't download films just browsing.