battery life for door/window sensors?

[magicmiles]

What is the normal life span for the batteries in the door/window wireless sensors?

[Kramer Chins]

I have seen somewhere that says a year. I change mine when we change the clocks... Just like your smoke alarm batteries. Might seem a little much, But I have several of my DS10A's modified to smoke alarms. So changing all batteries at the same time just makes sense.