Alarm app on my Ipad runs in the background with the monitor off and uses approx 10% of battery life overnight. More expensive hardware, but substantially more useful than a hand held gps
. In fact, that is exactly why I bought my Ipad. I wanted a backup gps
. I did not want an Ipad at the time and now don't know how I would get along without it. Rented movies
, real time weather radar
(when close enough to shore), wind charts
, email, navigation charts
, pictures, etc, etc.