Originally Posted by Cafe.Racer
Back on topic - if you have more than one detector, change the batteries in the other ones NOW!
We have three - one on each floor, and when on battery goes, the others start bleeping soon afterwards (usually at some ungodly hour).
If I could remember exactly what I did (other than a bit of brute force) to get the battery drawer out I would but I am just going to leave well enough alone for now!!