I have this clock now 7 years and have never had to be changed the battery. For the price very good. I had this clock several times while diving deeper than 40m underwater and remained completely dry. Really very good for the price. The operation is at the beginning a bit difficult, especially if you want to be storing numbers, but that's more of a gimmick and nothing you need. The display I well read and the clock is to use as an alarm clock.