Re: End-user Alert Delivery (was Re: NDAA passed: Internet and Online Streaming Services Emergency Alert Study)

[Chris Adams <cma () cmadams net>]

Once upon a time, William Herrin <bill () herrin us> said:
> Ordinary ionization-based smoke detectors use a 10-year lithium
> battery, which is about the same lifespan as the americium-based
> detector circuit as it begins to decay into neptunium.

Also, some detectors are wired to household 120VAC service, so the
battery is a backup, not primary, power source.  I think this is
required in modern residential building codes.  My house was built 30
years ago and has this.  I think larger homes even connect all the
detectors together (so one detector going off can trigger all to alarm).

And for typical 9V replaceable battery models, the "change the battery
twice a year" bit is not based on the actual load, but just trying to
get people to think about it (and maybe then getting it changed once a
year, which is perfectly fine and maybe even still more often than
needed).

-- 
Chris Adams <cma () cmadams net>