Neighbours Windows computer started losing some Cmos defaults and would not boot up Windows.


The Cmos date and time was ok so I didn't think the battery was a problem.


Reseting the default parameters fixed the problem for a few days.


Eventually I removed the battery and a test showed 1.8v - well down from the usual 3v.


A repacement battery fixed the bootup problem.


With the low battery I was surprised that the default settings dropped out and yet the Cmos clock remained ok.