10 Mar
2011
10 Mar
'11
7:59 p.m.
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.
Yes, I think you're right. The battery still has enough voltage to keep
the CMOS RAM contents preserved, but not enough to run the oscillator
properly. So the time runs slow (if at all) when the machine is turned off.
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.
I assume the manual says toy can connect an external battery even with
the soldered-in battery in place. It doesn't parallel them or anything
daft does it (if so, the external battery will try to charge the on-board
one with very unpleasant results).
Actually, I'd remove the on-board battery anyway. If it's failing, it may
strt to leak, and then you'll ahve bigger problems. is there any reason
you can't jsut replace this battery with a similar (electricallly) one?
If you do use the extranl battery connector, I would check that the
motherboard doesn't try to charge the battery (attempting to charage a
lithium coin cell is spectacualr, and you don't want to be near it. I
think there's a youtube video of it...). Connect a voltmeter across the
external bettery conenctor pins with the machine tunred on and check you
get no voltage there.
Is it asking for trouble to use a 3v rather than a 3.6v battery? If so,
It won;t do any damage, but you may just see what you are seeingnow. The
CMOS RAM data will be preserved, but the clock may not run.
where are the 3.6v batteries available?
There is a type of lithium cell that's 3.6V. I seem to rememebr that some
Macs used it.
-tony