A typical wireless burglar alarm battery requires changing every 2-3 years. The main panel is usually hard wired into the mains electricity and has a backup battery in case of power cut. This alarm battery usually will need replacing every 5 years or so.
The wireless sensors such as the door contacts and motion sensors usually take a CR123 battery, the life span of these is determined by how frequent the sensors transmit signal back to the main panel. It is recommended these batteries are replaced every two years. The outside siren batteries usually also get replaced around the two year mark, however this can be a lot less if the siren is always going off constantly.