Bluetooth and Wifi (not so much standard cell air connections) KILL batteries.
You can also get extended life batteries for most PDA/phone combos these days (except, of course, iPhone, which is hermetically sealed on Funk & Wagnall’s porch).
I used to have a Samsung and that thing died all the time. But I had a very weak signal here, so it might have been just that it was pinging the towers all the time. Thinking back on it, BT might have been on the whole time...