Relay-Version: version B 2.10 5/3/83; site utzoo.UUCP Path: utzoo!mnetor!uunet!seismo!husc6!think!ames!sdcsvax!ucbvax!COGSCI.BERKELEY.EDU!bryce From: bryce@COGSCI.BERKELEY.EDU (Bryce Nesbitt) Newsgroups: sci.electronics,comp.sys.amiga Subject: Re: Battery-Backed Clock Goes Back Message-ID: <8709032058.AA01589@hoser.berkeley.edu> Date: Thu, 3-Sep-87 16:58:31 EDT Article-I.D.: hoser.8709032058.AA01589 Posted: Thu Sep 3 16:58:31 1987 Date-Received: Sat, 5-Sep-87 14:15:57 EDT References: <8708300822.AA20905@cogsci.berkeley.edu> <4410010@hpcvcd.HP> Sender: daemon@ucbvax.BERKELEY.EDU Followup-To: sci.electronics Organization: ACME rubber hoser makers, Inc. Lines: 36 Xref: mnetor sci.electronics:1244 comp.sys.amiga:8064 [If you reply, be sure to strip off comp.sys.amiga from the distibution!] > In article <4410010@hpcvcd.HP> charles@hpcvcd.HP (Charles Brown) writes: >> >>...that battery should last somewhere in the range of 10-30 years... >>(="=) bryce@hoser.berkeley.EDU -or- ucbvax!hoser!bryce > >I find this hard to believe. Shelf life for Lithium batterys is about >three years, and those are long life batteries. Ok! There has been widespread disbelief in my statement that this battery could last 10-30 years. I can't argue the technical points, so I will just list my source; the data sheet for the chip. Thomson Components-Mostek claims to have some special longer life batteries. In the data sheet they have a formula for discovering battery life. It depends primarily on temperature. I can't reproduce the charts here, so if you want to see them get data for the MK48T02. Assuming a powered system, with no drain on the battery, wear out is almost exclusively a function of temperature. The chart goes from slightly over 2 years at 75 C to to over 100 years at 5 C. The three year point is at 70 C. When the battery is actually backing up the ram, consumption is a factor. Again the colder it is, the longer things will last. In a simple case with a constant temperature of 25 C and a 65 percent duty cycle the chart shows 10 years. At a zero percent duty cycle (always backing up) the life at 25 C is shown as three years. For more exact figures, see the data sheet. oo bryce@hoser.berkeley.edu -- ucbvax!hoser!bryce if "hoser" does not work, try "cogsci" If this article is mangled, let me know. This rn was finished compiling 10 minutes ago and may not be fully installed yet.