ipad charges very slowly

Hello,

My iPad Air has a problem.

Since a week now it won't charge as it normaly does.

Firts:

We had to put the chargers in and out for like 15-20 times before he started to charge and you can see the lightning bolt. After that he charged normal. The time of the batterie before it's empty is normaal. Many hours with not that much use. Nothing special.

Second:

Now it doesn't show the lightning bolt anymore when we plug the chargers in but is charges like 7-10 percent over a night. On this moment it's like 40 percent sinds monday when we pluged it in at 12 percent.

Did a restart, reset, dockconnector is clean, no dust in it. Original cable and plug.

The cable and plug work for my iphone. There is a update waiting but we can't install it because of the low batterie and hes says that is needs to be plug in.

Anybody has some clue?

Thanks.