How do in room hotel smoke alarms (NOT fire alarms) work and differ from home units of the same brand? How are they maintained and what's the wiring like compared to the home unit if any? Does the smoke alarm trip for THAT UNIT ONLY and the ones in other guest rooms remain silent? To further complicate things: If it's a 2 bedroom room with separate bed would the 2nd bedroom one sound as well tied to the parent alarm that went off?

Example 1: I was at Best Western to escape the Oregon ice storm for example and they use First Alert alarms which is what we have at home though ours are hardwired thru the mains with battery backup if power goes.

Also does independent hotels like Cave On Inn that are older or just renovated may have battery only in the rooms NOT connected to a main panel assuming it doesn't all cave in?