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[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"
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