Power management (original Airpad 7)

[dd-b]

So I've read that power gets used doing "phone" stuff even on these devices that don't have any phone content.  I looked in settings on my Airpad 7 (not 7p) and I see that mobile networks are enabled in settings.  So I've tried turning that off. 

People also talk about using various apps to help with power management, or setting airplane mode and then turning wifi back on.  Does that do more than  just turning off mobile networks in settings?

My Airpad 7 doesn't manage to sleep overnight with a full battery; *something* is eating power pretty badly.  (That's normal, right?  Other comments in various threads seem to confirm that.)