Per dave:
Turn off GPS. It will drain your battery fast.

That's what I keep reading, but it does not match my experience with a
Samsung 10" Note.

I rooted the thing and cleaned out everything I could think of and it
holds a charge so well that I hardly ever turn it off.

With GPS on I can leave it with screen black for a day and it will lose
less than 5% of it's charge. OTOH, maybe GPS is not working when the
screen is black..... ??
--
Pete Cresswell