My ideal would be
-- tri-mode (photoelectric + ionization + carbon monoxide) -- interconnected (all sound when one trips) -- operate whether power is on or off -- loud
I realize that I probably can't have it all, so I'm looking for the best compromise. I haven't found any place with really comprehensive listings, especially any which make it easy to determine what models meet which of my criteria. Consumer Reports has good descriptions of the issues but analyzes very few models.
So I'm looking for advice both on what compromises are most reasonable, and on specific models (possibly multiple models in combination) which might implement that compromise. I appreciate resources as well as direct information.
Notes on each of my items:
I probably don't need to explain why I want tri-mode -- anyone not familiar with the types can easily google them. I'm willing to spring for multiple detectors if there are no satisfactory tri-mode detectors available. (I haven't found any tri-mode detectors in a single unit.)
The advantage of interconnection should be obvious. Same for loud.
I'm unsure whether I want AC powered or battery powered. AC powered work without needing to change batteries and have plenty of power for a loud alarm. Battery powered operate when the power is out; I don't know if any of these can be interconnected. I know there are some AC powered with battery backup, but then that's still a battery to monitor and replace.
The big question with respect to AC vs battery is which is more effective overall. Power isn't out very much, but it does go out. In the house it probably averages a few hours a year -- once it was out for 18 hours after a severe thunderstorm, but usually it's not more than an hour or two, and it goes for months with no interruption at all. The mobile home is in a rural area and outages can be longer; it was without power for 3-1/2 days after Hurricane Kate, about 25 years ago. But are there any common factors to fire and power outage? Anything about a power outage that makes fire more likely? (Using candles and kerosene lamps would seem a significant risk. I have battery operated lights instead.) Perhaps an electrical malfunction could start a fire but then trip the breaker powering the detectors before they sound the alarm? On the other side, weak batteries are an obvious risk, albeit one which regular testing ameliorates. So neither is perfect, but what are the probabilities of a multiple failure? That is, power outage plus fire, or battery failure plus fire, or alarm not loud enough plus fire, etc? Are there other common mode failures?
In the house, I can easily run AC wiring and/or interconnection wiring in the attic. In the mobile home, I might be able to run it above the ceiling, or I could gouge a trough in the ceiling tile or just run it along the upper corners -- the place doesn't look good enough for me to worry about the damage.