Racer, I'm sure you meant to write 4.5mAh for the battery capacity. VERY different to a 4.5MAh capacity battery. The latter is 1,000,000,000 more capacity and would not have fitted into the alarm. It may fit into your room! Capitilisation is very important when writing any units down.
As Luop said, it will go in if it fits physically.
Regards
DKit
