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Not charging ..
Battery indicator displays " not charging" ...but unplug the lightning connector from the port and iPad is definitely charging !? What's that all about ?
Comments
I think it means it is charging but at a lower rate than is optimum....if I connect my iPad to a USB port on my PC at work it says not charging, but it is, albeit very slowly.
Could you have it plugged into an adapter that is putting out less than required? An iPhone charger delivers 5 Watts (5 volts at 1000 mA). A Retina iPad mini charger delivers 10 watts (5.1 volts at 2100 mA)
Check your lightning port for blockages. Tends to affect iPhones because you keep them in your pocket but could be a cause here.
Makes sense .. it isn't the correct charger ..cheers mate.
Yes! As above. Cheers
Almost same issue this week only mine wouldnt charge at all. Was working on a song inside cubasis and plugged it into the adapter with 30% battery left. An hour later suddenly my iPad shuts down with 0%. and it took me an hour before it had enough power to come back online. Think it's an iOS bug.
Edit: Unplugged and reconnected the cable about 10 times before it would charge again.
Since iOS 10 I get the "not charging" message when connected to my computer via USB.
Apple 
If you turn the iPad off, it is slowly charging but if it's in use it will generally not maintain charge level and eventually run out of juice.
Same setup on iOS9 seemed to at least maintain the battery level, so I guess the newer OS requires more power.
More likely your battery is getting old...
Never had any issues before and think it's because of the latest iOS update that I downloaded to be installed at the next reboot. It's working fine again.
My AIR 2 runs like my iPad 3 at this point in some respects due to battery.
If I charge it only lasts 20 mins before dead again
I’ve gotten this too. I assumed it was my cable going bad. (I was also getting “This device is not supported “ occasionally.) Just as an experiment, I swapped out the power adapter, which was the official Apple one that came with the iPad, for a cheap generic one I had. The problem went away.
After about a week, I switched back to the original official Apple adapter (same cable the whole time) and the problem has not returned. (Maybe it happened once in about a week; can’t recall, but before I was getting it several times a day.)
My current theory is that it is something about the power strip (6-socket surge protector) into which I have been plugging the adapters. The Apple adapter was wider, so I switched sockets for the generic adapter. Maybe dust or something or just something better about the next socket?. Try switching to a different outlet source, or just reseating the adapter to make sure you have a solid connection.
so my iPads been on charge since 9.30am (5 volts 1000 am iPhone charger) and it's just hit 57 percent charge.
Definitely suspect, as judgedredd pointed out, the charger.
I have seen this before in both surge protectors and ground fault circuit interrupter (GFCI). Something about the monitoring circuits in some of these devices cause an interference when you have a device that (looks) at its power source and what its connected to.
I also think iOS 11 might be part of it. I never saw this issue before 11. I think maybe it made iPads more persnickety about power sources.
And the win goes to the person that uses persnickety in a post!
Such a fun word, you made my day.
Oh sure, it starts off innocent enough. All the cool kids are using “persnickety.” Before you know it, you move on to the hard stuff—“fastidious,” maybe a even “flibbertigibbet.” Next thing you know you’re out on the street corner looking to use “jiggery pokery” in a sentence. Vocabulary is a slippery slope, my friend.
If I were a fastidious type of person with a jiggery pokery type additude, I might think you may have been a flibbertigibbet at some point in your life.
Just so you know, I came dangerously close to covering my computer with coffee. It don't like coffee that much.
To me it sounds more like that the lightning port may need a bit of cleaning
(I've done that a few times on my iPhone & iPad).