Path: utzoo!utgpu!news-server.csri.toronto.edu!cs.utexas.edu!wuarchive!rex!ames!sgi!rpw3@rigden.wpd.sgi.com From: rpw3@rigden.wpd.sgi.com (Rob Warnock) Newsgroups: sci.electronics Subject: Re: Reply: NiCads in Smoke Detectors Message-ID: <90127@sgi.sgi.com> Date: 10 Mar 91 18:08:17 GMT References: <1991Mar1.145532.7118@lonex.radc.af.mil> <5170116@hplsla.HP.COM> < <88597@sgi.sgi.com>> Sender: guest@sgi.sgi.com Reply-To: rpw3@sgi.com (Rob Warnock) Organization: Silicon Graphics, Inc., Mountain View, CA Lines: 37 In article schumach@convex.com (Richard A. Schumacher) writes: +--------------- | OK, now two folks have opined that lithium batteries will probably | work in a smoke detector, even though one pointed out that the | Li battery has ~16 ohms internal resistance versus ~.8 ohms for | the alkaline. It would seem safer to contact the detector manufacturer | to ask whether it's OK rather than assuming it is, given that they | all do specify using certain batteries. +--------------- As the one who said that lithium batteries have higher internal resistance, let me reassure you that this only makes a difference *during an alarm*. That is, a lithium battery will dissipate a little more of its power internally under *heavy* loads. (I.e., when the alarm is squalling and bouncing you out of bed!) If you are concerned about it, test one in your detector, with a cigarette or some other source of smoke to set off the alarm. Compare the volume with the lithium to that with an alkaline, and make your decision based on that. The increased internal resistance matters not a bit to the service life of the battery, as the standby current of the alarm is in microamps (or less). There, the lithium wins. [While it can't hurt to ask the alarm manufacturer, the difficulty is finding the right person to ask. It's all too easy to find a marketing dweeb who'll tell you anything just to get rid of you. And if that causes you to incorrectly choose a less reliable battery...] -Rob ----- Rob Warnock, MS-1L/515 rpw3@sgi.com rpw3@pei.com Silicon Graphics, Inc. (415)335-1673 Protocol Engines, Inc. 2011 N. Shoreline Blvd. Mountain View, CA 94039-7311