We inherited the optima xm alarm system, but have recently found, during a power cut that it has no back up battery installed. What type of battery do i buy? How do i install it? Are you allowed to install it yourself, or do you need an electrician? Please help as my ears are still ringing.

Karen, May 2008

It's easy to fit the battery - you will need a 2.1Ah if it's a compact panel, or up to 7.0Ah if it's full size. Have a look here http://www.diy-alarms.co.uk/catalog/how_to_10.php for more info

howard, May 2008