Seven Things to Consider When Choosing a PDA by Jason Kohrs
... Manufacturers may provide a figure on the normal life between charges, but this is most likely based on occasional use, where it is idling for a majority of the time. This figure may indicate battery life of up to several days on one charge, but under more intensive operation, the battery life could be cut significantly. Watching a movie, listening to audio files, or playing games may drop the life on one charge from a few days down to a few hours.