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From: ijk@cbnewsh.att.com (ihor.j.kinal)
Newsgroups: sci.electronics
Subject: Re: Reply:  NiCads in Smoke Detectors
Summary: other 9V batteries in smoke detectors
Message-ID: <1991Mar7.202552.26671@cbnewsh.att.com>
Date: 7 Mar 91 20:25:52 GMT
References: <1991Mar1.145532.7118@lonex.radc.af.mil> <5170116@hplsla.HP.COM> <88597@sgi.sgi.com>
Distribution: na
Organization: AT&T Bell Laboratories
Lines: 24


Most brands of smoke detectors I've purchased recently SPECIFICALLY
state to use only the REGULAR type of 9V - thereby excluding alkaline
or lithium [or ni-cad] cells.

Since these regular 9volts typically come in a 2 pack, which costs
almost as much as an inexpensive alkaline, and since the storage
life of these regular batteries is minimal, the second battery
usually goes to waste [or could I freeze it to extend the storage
life??].

The question I really have, is assuming that the smoke detector
people know what they're talking about, is why???  Are the
internal resistances that different, that it makes a difference???

[I remember that power transfer is greatest when the internal
resistance is equal to the external, but a smoke detector is
not a car starter equivalent, is it???]

Just curious [hey I'm basically a software person] and
include standard disclaimers:
	from
Ihor Kinal
att!cbnewsh!ijk