Ideally, how often should the control panel battery be replaced? I have a Phonewatch control panel. My contract is up soon and I am currently looking at alternatives.
Depends on the quality of the battery used, but 3-5 years would be a typical service life. These are usually sealed lead acid .
Also how often should the others - Pirs and doors/windows batteries be replaced?
Probably ~3-5 years, but will depend on factors such as distance from main panel, how often they are triggered, etc.
I was quoted €5 for each battery change and €20 for the control panel battery by a local service company - one I am considering as a Phonewatch alternative.
The wireless sensors generally use CR123a [broken link removed], most Irish shops will charge €4 plus, but you can get them cheaper online. The panel will report battery low faults for these sensors, and you can replace them yourself without the engineer code if you're OK with the alarm triggering once you open the sensor to replace. A second person ready to input your code at the keypad will lower the nuisance level for your neighbours.