[OtinG]

Well you could probably build a Faraday cage to block the electromagnetic waves. BT uses radio waves which are electromagnetic waves. Sounds complicated, but it is a very simply thing. Place the AP1 inside a small metal container and the metal will block most, if not all, of the BT radio wave signals from entering/leaving that container, therefore the AP1 and iPad will think they have lost contact with one another and eventually they will stop trying to re-establish contact. A large metal cigar tube would work. A small box lined with aluminum foil or aluminum tape would work. A small cookie tin made of metal would work.

In theory I've heard that the AP1 is supposed to stop attempting to contact the AP1 after it loses BT connection. If it really does stop wasting energy trying to reconnect, then blocking the BT signals should cause it to stop wasting that energy and give up trying to reconnect. I have no clue if Apple actually built in that function, but if so then blocking the BT signals should save energy and not cause you to go through turning the BT on/off on the iPad. In other words, you could leave BT turned on all the time. So when you get ready to reconnect the AP1, you would only need to plug it into the iPad's lightning port for a few seconds until the iPad reconnected, then unplug and use it.

The easiest way to try this would be to loosely roll the AP1 up inside a sheet of aluminum foil.

On the other hand, a better solution might be to simply buy a dedicated charger for the AP1 and place it in the charger when not in use. That is what I do.