Notebook PC loses time when main battery removed

I bought my first portable computer, a Compaq Presario notebook PC, in July 2007. If I use it without the battery in it, i.e. run it off the power cord, and shut it down and let it sit overnight with the battery not in it, it loses time; it loses hours, not just minutes.

I presume this indicates the CMOS battery is weak. Am I correct in thinking this computer should be able to retain the time overnight, just as my deektop/tower PC does?

 

Windows based laptops (as oposed to Macbooks) have a CMOS battery that should retain system settings such as current time. If the CMOS battery was dead/weak, your time should be resetting to the same date such as 1/1/1980 or something like that. Also, if you AC adaptor is plugged in, the laptop should be able to retain CMOS settings even if the battery is dead.

 

Thanks for the reply. If the AC adaptor is left plugged in when the computer is shutdown, it does not lose time. But, if the AC adaptor in not left plugged AND the main battery is not in the computer, then it loses time. I am not absolutely sure but I believe this time loss does not occur if only left off a few hours; it's when it's left off overnight that I've had to reset the time. And, the time loss is not the full length of time that the computer was shutdown; for example, if it's off for 9 hours, it may lose 3 or 4 hours.

 

the timing of the occurrence seems to indicate a bad CMOS battery, but the time should reset back to defaults. Regardless, if the CMOS battery is cheap, you should replace it.

 

I agree with your advice, Senlis. But, I've been looking for some online sources and find that the little rascal isn't cheap. The lowest cost I've found so far is about $40, with shipping. I thought it would cost less. I may hold off awhile and see whether the time loss problem gets worse. I don't see it as a serious problem. I don't have any non-default settings currently set in the CMOS setup screens, so the only problem is the time. So, I may just continue to reset the time as needed.

 

You may change a CMOS setting such as boot sequence and see if it looses that the next time this happens.