do you have the connexion? I heard the batteries in the UK version last longer than those in the US version. And it also depends on how much you connect with other tamagotchis. The infrared communication is what makes them die fast. And you'll know when the battery is dead, there will be a battery on the screen with a big x going through it. Also, just 'cuz the battery dies doesn't mean your tama is lost. After you put the new battery in, push the middle button and you will be prompted to either download or restart. If you download you will get the last tama you had in the condition you left it in.