why does my ipad go dead?

Hi,

I have iPad 3 with os before 8.4 which I am now dowlnloading.

Twice now over tyhe last 2/3 months I have come to my iPad in the morning afternit charging all night to find it 'dead' or so it turns out, 'faking death'.

The first time I plugged it into the computer and itunes and it was good, then today after trying about 10 times with no effect, the apple came up after holding down the Home and Power kets for 20 or 30 secs.

When it comes alive it shows ar 95% bor battery so it is not the battery charge.

What couldbe casuing this? Is there an error log file somewhere that may tell me what is gouing on?

I am now paranoid one day itb will not come up and I rely on this thing for public speaking etc so couldn't have it die on me.

I have also noticed that sometimes the power lead does not connect properly until I mess with it and then other times it says it may not be supported., ??

Any ideas please?

Thanks

oz