The battery in my iPad (Air 2, I believe, and perhaps three to four years old) has been giving me fits lately. It has gone from 100% to 71% in a few minutes, but it has also held steady at 94% for a long time. In short, it varies, with no pattern that I can recognize. Twice, the iPad has shut itself off, with the battery indicator in the 90s once. The battery charge percentage has declined while it was connected to a charger and the charging indicator was green! Also, I have shut down the iPad and promptly restarted it (without a power connection) and seen the battery charge jump from 71% to something in the 90s. (Why should 71% show up twice in this paragraph and more times that I haven’t mentioned? What is special about 71%?)
My current working hypothesis is that Apple tests for something (probably voltage) that is a proxy for battery condition, and that proxy is not a good indicator of actual battery condition. (I’m running iOS 11.2.6 and, as far as I know, do not have access to any battery condition indication other than the percentage shown at the top of the screen.)
I assume it is the battery and plan to get it replaced if no one argues against it. Giving someone the chance to argue against is the main reason for this post, since I have little to contribute.
But there is one observation I will make, in case anyone can confirm or refute its significance. The problems started fairly abruptly during a trip overseas, when I used the slick Saunorch International Travel Power Adapter mentioned in Adam’s article on travel to the UK. Could the power adapter have damaged the battery? The other notable incident on the trip was using the iPad until the battery got down to under 30% (and perhaps down to 10%, I don’t recall), which was the lowest it had been in its life. Maybe the battery was just old and that stress pushed it over the edge.
Thanks for any advice and you’re welcome if this triggers a thought about what ails someone else’s battery.