Does low CMOS battery affect the OS

Toshiba Satellite A45-S12
October 21, 2008 at 19:00:49
Specs: Windows XP Home, 1GHz
Hi all,

I have an old Toshiba Satellite laptop (that belongs to a friend who have abandoned this machine for me to fix) that

I'm going to replace the CMOS battery for. Right when I turn the machine on it tells me to press F1 to enter BIOS

because of [I]CMO read error or CMOS checksum error[/I]. I am convinced that once I change the battery this

particular problem will be gone. After all it has been used for many years.

Furthermore I have some suspicions though about the nature of this problem. The reason my friend ditched this

machine is because it would not boot up completely -

At some point while the winxp logo is shown during the startup process, a blue screen appears for about a TENTH of a

second, and the computer just simply resets/restarts itself.

My question is, could this problem have anything to do with the fact that the CMOS battery is low?

Any advice or insight is appreciated.

p.s. - the laptop itself is spyware/virus free.

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October 21, 2008 at 19:15:29
It's not likely that the battery would cause the problem that you described. The battery is just used to keep the bios settings from being lost when power is removed from the PC.

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October 21, 2008 at 19:18:08
XP doesn't need the bios as much as older MS OS's.

It is possible that the cmos could do that. In some systems the cmos is part of a real time clock device. A dead battery drags down the system time. Most laptops do have a real simple battery that one can access if they take apart the system. It still may have a component device with battery installed that you can't easily see.

Batteries cost pretty cheap, dunno how much the laptop is worth.

"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10

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October 21, 2008 at 19:32:35
You could remove the CMOS battery for a few minutes, that should reset the settings to their default value. The Laptop should be operable with the default settings.

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October 21, 2008 at 19:34:08
aegis, I didnt think the cmos battery would affect OS either since its job is to save system configuration and keep the cpu clock running. But after what jefro said I'm not so certain.

Whether it is the battery or not, I presume it's worth a shot to change the battery and see what happens. I'm just worried that it's more hectic than just unscrewing a few screws.

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October 21, 2008 at 19:52:33
Fact you are getting the message you are, it's not a matter of the battery being low. It's dead. Cmos isn't keeping the settings and is defaulting to what was originally burned in as defaults.

ALL OS's listen to what is reported from the bios. EVERY OS, every bios. The bios is what tells the OS what hardware is available and what state it is in.

The system clock needs the bios battery to keep time when the power is turned off. No battery no time. Again you are back to bootup defaults which is usually back to bios original date and time. The OS reads the bios for time so time in the OS would be the date and time of the bios. Only if the clock chip [quartz] was defective would time "drag".

A number of older laptops have soldered in batteries. They are not replacable by lay people. You should go to Toshiba's web site, look up the model and tech specs and see if the battery is replaceable. You would need to take it in for service since laptops are not like pcs.

Your question of OS boot CAN be effected by what the bios is now reporting [defaults] vs when the OS was installed. Things like power management and devices are critical.

But what you describe is more of a file system corruption, OS corruption or spyware infection.

A system repair or complete reinstall will fix the OS issues.

I wish I could say more about some, not all, of the advice you have recieved but in the interest of the site I will refrain.

Best of luck in your endeavors.

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October 21, 2008 at 19:54:47
Of course there's no guarantee, but I would be willing to put a sizeable amount of money on a bet that replacing the battery will not fix the problem. However I have to admit that I have seen stranger things happen.

But I think a 'repair install' would have a chance of doing it, 'if' the Toshiba recovery CD has that option.

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October 22, 2008 at 20:29:30
i wouldnt think that the CMOS batt being dead would cause XP to BSoD, unless as stated above, the BIOS defaults to a config that causes XP to loose its marbles.

on most laptops that i have worked with, the only real Win-related issues with a dead CMOS batt are the Clock control panel is always resetting itself back to 12:00AM @ 1/1/2003 or something. and the other issue is when you log into a web site over a secure connection, it will complain about the security cert not being valid (it really means the clock is not set)...

i think your problem lies within Windows and yeah, i'd try a Windows XP CD for a Repair install.

- Baloo

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October 23, 2008 at 10:08:55
Thanks you for all the advice. I found out that the laptop - Toshiba Satellite A45 series all use the same kind of battery, and I found a replacement part on ebay:

I just have to find out how to take it apart and replace it.

The best part though, is that I've pinpointed the problem with the bsod. i simply ran chkdsk /r, fixmbr and fixboot in recovery console using an xp setup disk. It repaired the boot sequence and file system from being corrupt and I was able to boot into desktop and use it. I will do a complete reinstall once everything has been backed up.

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October 23, 2008 at 12:32:25
cool... glad to hear that...

most laptops have removable CMOS batteries... some are a standard CR2032, some are a smaller watch-type battery, and some are standard pigtails (cr2032 with 2 wires attached that go to a plug) and some are odd looking pigtails (like yours)...

as for installing it, i'd try Toshiba's Web site for a disassembly guide or service manual. they should have something that shows an exploded view followed by a step-by-step howto on dismantling the thing. oh and it'd be a PDF doc.

- Baloo

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October 23, 2008 at 15:27:14
OH my. For some reason I thought you had tried to load an OS on it.

"Best Practices", Event viewer, host file, perfmon, antivirus, anti-spyware, Live CD's, backups, are in my top 10

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November 3, 2008 at 16:15:15
Hello..I'm having the same issue with my Toshiba Satellite a45. Replaced the RTC battery and still can't get in to reset cmos values with the F1 key. Have you had any luck?


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