CMOS Battery for PC/AT

From: David C. Jenner <djenner_at_halcyon.com>
Date: Mon Mar 23 19:53:06 1998

This is a great idea, but after scrounging around, I got a replacement
for about the cost of this workaround. I found one place that wanted
$20
but finally found a Radio Shack that had one for a lot less. The
battery still cost a lot more than the PC/AT!

Thanks,
Dave

Tony Duell wrote:
>
> >
> > I picked up an original PC/AT that has a dead lithium battery for the
> > CMOS bios parameter storage. The battery says it's 6.8 volts. It's the
> > kind that is a 1/2x1x2 inch pack with a six-inch lead.
> >
> > I've tried several places to find a replacement, but either a store
> > doesn't have it, or, if they have one, the voltage is not exactly 6.8
> > volts.
> >
> > So, what's the acceptable voltage range, especially on the low end? And
> > any good sources?
>
> Well, the voltage is not that critical.
>
> I also have a PC/AT (original type 2 system board), and the battery in
> that was dead when I got it. It claimed to be a 6V battery. I managed to
> find a place to buy a replacement, but it was \pounds 14.00 or something
> equally crazy, so I made a replacement :
>
> 1N4148
> +------->|------+----------( +ve
> | |
> ----- /
> --- \ 100k
> ----- /
> --- \
> ----- |
> --- |
> ----- |
> --- |
> | |
> +---------------+----------( -ve
>
> The battery was 4 AA alkaline cells in a standard holder. The diode/resistor
> were added since 4 fresh cells gave about 6.6V, and I was worried about
> killing my RTC chip. In theory it'll cause the battery to run down a
> little faster, but mine's lasted about 4 years so far. I cut the cable
> off the old battery and used that to connect my kludge to the system board.
>
> And next time it fails, 4 AA cells are a lot cheaper and easier to find
> than the official battery.
>
> >
> > Thanks,
> > Dave
> >
>
> -tony
Received on Mon Mar 23 1998 - 19:53:06 GMT