A method and an apparatus for system acquisition at a wireless device while maintaining a predetermined battery life span, include determining a level of remaining battery power upon entering an out of service state. A duty cycle, comprising a search time and sleep time, of acquisition attempts is determined such that the level of remaining battery power lasts for the defined battery life span. The duty cycle is determined by adjusting at least one of the search time and the sleep time, depending on how long the remaining battery power is required to last.