"Dave D" wrote in message
...

"jw 1111" wrote in message
...
hi, in an old pc i have had second hand for five years or so it says it
the instruction booklet that it has a lithium battery in the system board
can be replaced.

how would i know when this needs to be replaced please? will the whole
p.c. just stop working? thanks


Usually, what happens is that the settings in the system's CMOS (AKA the
settings in the BIOS) will be lost and require reconfiguring. As many
systems just run with the defaults anyway, these days it isn't much of an
issue. I would expect the battery will be getting low. I've known them
last a lot longer than 5 years, but I've also seen them last less than one
year!.

Generally, when you switch the PC on and you get the POST screen (the
first thing you see when you power on, when it does the memory count) it
will notify you if the battery is low with a message similar to 'CMOS
battery low'.

Most modern systems have a system monitor function in the BIOS, where you
can find out things like power supply voltage, CPU temperature and CMOS
battery voltage. To access the BIOS, consult your manual or watch for any
onscreen instructions on power on, usually something like 'press DEL to
enter BIOS'. If yours has a hardware BIOS monitor, check the CMOS battery
voltage is not significantly below 3V, ie 2.9V or 2.8V should be OK.

If your system does not have such a function, and it may not as it's
getting on in years, you can pop the battery out and check it with a
multimeter. Failing that, just replace it, they're cheap!

Dave
I know on older computers when the battery was dead you would get the "non
systems disk, please replace diska nd hit enter" message or messages asking
for date and time.