7 Jun
2008
7 Jun
'08
10:40 a.m.
On Saturday 07 June 2008, Chuck Guzis wrote:
A diode in series with the battery pack should disable
the charging
circuit and drop the pack's voltage to near-optimal. (3x1.2 NiCD =
3.6v; 3x1.5 primary = 4.5v - 0.7v for the series diode = 3.8v; pretty
close). If the battery's function is to keep the clock and some RAM
alive, 3 "D" cells will probably last a year or two. Make them
Lithium-iron cells and you'll probably get 10 years of service.
Another option that I've used before (especially if you don't intend to
leave the machine powered off for a long time) is to use one of the
0.1F or greater 5V electrolytic caps that are meant for a "memory
backup" application.
Pat
--
Purdue University Research Computing --- http://www.rcac.purdue.edu/
The Computer Refuge --- http://computer-refuge.org