I regularly used my IPad a good 12 hours a day, I normally leave it plugged in as I don't go anywhere bar the desk I sit it, I I'm wheelchair bound and housebound, rather than a lazy git.

But it seems to be going down a good 80 percent in that 12 hours even if I leave it plugged in.

Normally use it for radio, and playing Football Manager Mobile.

Could it be my charging lead, or the adapter I use to charge it with

Try turning off all but essential push notifications, close all open apps and switch off any unnecessary location services.

That said, games eat power these days.

Sounds daft I have a double USB Charger plug, could it be that

Probably a poor charger not putting out enough power - had this with an Android phone when charging in the car when being used as a sat nav. It used to drain the battery despite being charged. A new charger solved it.

So the lead more than the adapter plug then, a shame as the lead I bought only a few months ago from Amazon it's RRP was getting on for 60 pounds and got it for a tenner

For some reason my brightness was on full, even though it was set to auto brightness, maybe I need to reset my ipad

Was it a branded one?

Both the charger and the lightning cable are important. I always recommend Anker as a brand for things like this unless you go for the official Apple products

Yes but chucked the box out so I can't remember.

Yes I Love Anker, I have a glass screen protector, and a Bluetooth Keyboard from them.

Do you still have the lead and adapter that came with the iPad? If so have you tried them to see if it is any better?

I have a mains adapter which also has 2 usb sockets on the top but I rarely use it as it doesn't appear to have anywhere near the same charging ability as the Apple adapter.

You need a 2.4A 12w charger for the iPad Air, like the one that came with it.

have you tried another device's charger in that plug socket? I've just found out I have a dodgy socket in my flat when a friend couldn't charge his phone properly. Moved wall socket and it was fine. Some devices work fine in that socket (??).
Otherwise, might be time to buy a new charger? Have you asked Apple if constantly using the iPad on power hungry games while it's on charge can cause problems?

Get a PC or if you feel its needed another Apple machine, much better for desktop use.

I'm sure op will appreciate your helpful reply