Re: BIOS backup battery

The message <PMGdDpAiodiEFwrZ@xxxxxxxxxxxxxx>
from thoss <usenet@xxxxxxxxxxxxxx> contains these words:

On Fri, 9 Jun 2006 Mark wrote:

My PC is 7 years old (yep!) and still on the original mobo backup
battery.

I have just bought some CR2032 cells for various uses around the house
- should I replace the PC BIOS backup battery before it fails or when
it fails?

Battery should last 5 years or more.

Anywhere from 18 months (PC Chips MoBos, typically) to 50 years (estimated).

A 5 year figure with a CR2032 (180mAH) would imply a 4 micro amp load
from the RTC circuitry which is within the spread of 0.1 to 10 micro amp
readings I've taken.

The percentage of 'on time' per day will extend the estimate, a 50%
figure doubling the endurance (ignoring the fact that ATX standby power
can extend this to infinity if the mains supply is never disconnected
:-)

Shelf life refers to how long the cell or battery can be stored at a
particular temperature (usually 20 deg C) before it loses 10% of its
specified capacity.

Lithium cells usually have a ten year shelf life figure which implies
they will still have 80% capacity if left for _twenty_ years on the
shelf. Another twenty years of 'Shelf Life'(tm) will drop the capacity
to 60%.

In fact, if you only need half the origional capacity of a lithium cell
or battery over a 50 year period, you've cracked it! :-)

--
Regards, John.

Please remove the "ohggcyht" before replying.
The address has been munged to reject Spam-bots.

.

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