Well, given one of the Family Shield alarms was going off when I simply re-inserted the battery this would indicate a failure of either the "10 year" battery (that was two years old) or the unit itself, versus its placement or specifics of its location in our house. That said, the other one would go off only at night, which makes me wonder it was related to the drop in voltage in the cold (old house with high stud, and it can get cold at night). But would that make the alarm emit a warning chirp or actually set it off proper? In our case it's the full-on alarm that goes!

As these cheaper Family Shield and Warrior alarms prove, one doesn't have to pay $50 for each alarm to avoid annual battery changes, as both of these are "10 year" units; it's just that both seem like they're prone to false alarms (so to speak!), hence my question as to whether the Cavius alarms are at all prone to the same problem. Still no idea on this yet!

I think I'll get Bunnings to do the beat by 15% thing on a couple of Cavius alarms, as $42.50 an alarm sounds ok. But still not sure regarding the value/importance of having the "thermal" model in the kitchen/dining, so would love some advice on this too...