10 Mar
2011
10 Mar
'11
1:10 p.m.
On 2011 Mar 10, at 12:25 PM, Dave McGuire wrote:
On 3/9/11 10:37 PM, Hollandia at ccountry.net wrote:
On occasion I have dealt with this by installing a 2 or 3 cell AA or
AAA battery holder somewhere in the machine, well away from the
electronics to avoid corrosion from leaking or off-gassing (behind the
false front on some machines can be nice, or even on the back panel
exterior).
I then use junk alkaline AA or AAA cells which have been exhausted in
use for things like flashlights and remote controls, as they can still
have enough energy to run an RTC for a very long time. Alkaline cells
have a very long shelf life, making them good for very-low-current
requirements such as RTC and config-RAM maintentance.
As others have said, a blocking diode may need to be installed to
prevent 'charging' of the alkaline cells, but the 0.7V drop of the
diode can be accounted for in the number of cells used. Typically for
alkaline cells: 3 cells * 1.5V - 0.7V = 3.8V, with lots of room for
droop from an old/used cell.
One of my computers is a 486SX. The soldered-in
battery is apparently
failing; after a period of power-off, the time is badly off at
re-start. The
date and BIOS are so far unaffected.
The motherboard has provision for an off-board battery. I am thinking
of
using a socketed CR2032 battery which I believe is rated at 3 volts.
The
manual for the computer describes the off-board battery as 3.6 volts.
Is it asking for trouble to use a 3v rather than a 3.6v battery? If
so,
where are the 3.6v batteries available?
3.6 is 3*1.2V, and 1.2V is the intrinsic cell voltage for several
battery technologies, such as NiCd and NiMH.
3.6V is the intrinsic cell voltage for LiIon cells.
Is the motherboard expecting to charge the battery?