This computer can't tell the time!

[CotswoldCS]

I have an old Pentium 166 computer which is working fine with the exception that it cannot keep the correct time. The date/time just stops when the computer is turned off and continues from where it left off when it is powered up again. It sounds like the CMOS battery is dead, but surely all the BIOS settings would reset if the battery was dead???? I have tried changing the time in the BIOS and from Windows but every time the computer is off it stops.

Is it just a duff battery or could it be something else. I don't have a spare battery to try otherwise I would have done that first.

 

[Ark]

Normally if battery goes bad, clock stops working first, BIOS settings will stay for a while.
If clock stops with power off it is battery, is clock works incorrect with power on it should be oscillator cristal.

 

[CotswoldCS]

Many thanks for your quick response. I think you're right but was grateful to have it confirmed. I didn't want to go and buy a new battery and find that it was something else.

Are all CMOS batteries the same???? This one is a 3v lithium bat.

 

[Ark]

I know about the clock problem, because I have old P-166 computer at work with poor BIOS chip, so battery goes dead every 3-4 months.
The first symptom usually incorrect time after PC was off overnight.
It usually works 3-4 week like that before BIOS setting lost.

So I am sure this is a battery in your case.

Few different batteries available, but most common is 3032.
I think 3016 also will fit, but has less capacity.

 

[CotswoldCS]

Cheers Ark!!!!!!