When this thread came up, my first thought was that I usually get close to a week out of a charge with my mx-880. Knowing that I had given it a full charge on the 10th I figured I would keep track and sure enough, 7 days later its just now ready for a charge ( battery is at 20%)...

I watch a good amount of tv each week, and for me the trick to getting a week out of a charge as opposed to a couple days is to make sure that I don't keep the remote in the chair with me... If the remote is in the chair, the screen/buttons turn on every time I flinch and kill the battery.. Depending on where I am sitting, I make sure to leave it on the floor, the arm of the chair next to me, or a table and it easily doubles the time between charges