# can bad cmos battery prevent laptop posting?



## HermitJohn (May 10, 2002)

I had messed with one of my old laptops when I had memory problems with my desktop. It worked. Desktop now working fine. 

But today for heck of it tried booting up the other two old laptops. Hadnt used them in years. Neither would even turn on with laptop battery in or out. One when I plugged in power supply, the charging light would come on, but then go out within couple minutes. Both worked fine last time they were used.


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## Nevada (Sep 9, 2004)

HermitJohn said:


> I had messed with one of my old laptops when I had memory problems with my desktop. It worked. Desktop now working fine.
> 
> But today for heck of it tried booting up the other two old laptops. Hadnt used them in years. Neither would even turn on with laptop battery in or out. One when I plugged in power supply, the charging light would come on, but then go out within couple minutes. Both worked fine last time they were used.


If the CMOS battery goes dead you can expect two things; 1) the BIOS settings will revert to factory default, and 2) the real-time clock will revert to the base time (usually 1/1/1980 or 1/1/2000). The effect of the BIOS reverting to factory default is that it will take longer to boot because the BIOS has to scan for installed hardware. The effect of the real-time clock being set wrong is that you'll get messages that the security certificate is out of date for any web page that uses https.

Sometimes you have to help the BIOS out by going into the CMOS setup while booting. See if it will go into the CMOS for you.


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## HermitJohn (May 10, 2002)

Neither laptop even try to post. Nothing, nada. NOt with laptop battery in, not with laptop battery out. Both worked last time used "years" ago. As I say the charging light comes on for brief period on the one laptop, then goes off without battery being charged. NOthing happens with the other one, nothing, no lights, nothing. And these fold say bad cmos battery can cause this symptom: http://www.johndscomputers.com/2011...mputer-wont-boot-might-be-a-bad-cmos-battery/ I dont know, my experience is as you state, clock settings arent saved, but computer posts and boots. Maybe an error about bios settings or some such. But nothing that makes the computer not even try to post. But what else could cause this just from laptops setting unused in an old file cabinet for very extended period of time. The third laptop that I used worked without problem and was stored in same file cabinet drawer with the other two. Its the newest of the three, thus reason I used it.


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## Nevada (Sep 9, 2004)

HermitJohn said:


> But what else could cause this just from laptops setting unused in an old file cabinet for very extended period of time.


I'm not sure. Is anything else working when you try to power it up? Do any lights come on, or does the processor fan start?

A memory fault can keep a laptop from starting. Try removing and reinserting the memory modules. Also make sure there's nothing in the optical drives.


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## HermitJohn (May 10, 2002)

As I say, the battery charge light comes on for a brief time (if laptop battery is installed), but goes out soon after with no charging taking place. I just tried after removing the dvd-rom completely. No difference. Nothing happens with the other laptop, no lights, no nothing. It is a Toughbook C50 and used to be dead on reliable. Looks like only one stick on the Asus and I need screwdriver to get to it... It maybe built into the motherboard so not removable. Most of these have two slots you can get to without screwdriver. Only one empty slot with cover removed.


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## HermitJohn (May 10, 2002)

And if there is enough memory problem that it cant post, shouldnt it beep a warning or dont they do that anymore? How does anything but the cmos battery deteriorate just setting unused in a dry drawer? And two laptops having same problem???


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## Nevada (Sep 9, 2004)

HermitJohn said:


> And if there is enough memory problem that it cant post, shouldnt it beep a warning or dont they do that anymore? How does anything but the cmos battery deteriorate just setting unused in a dry drawer? And two laptops having same problem???


Yes, motherboards usually send a beep code when no memory is detected.

I wish I could help, but reseating the RAM is the only thing that readily comes to mind.


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## HermitJohn (May 10, 2002)

Ok, found another power supply and got the Toughbook to flash its lights, but no fan, no post. Screen remains black. I plugged in external monitor, same results. I did reseat memory stick and hard drive. It is trying to charge the battery. So leave it do its thing overnight. This was neat old laptop. But maybe too old. One sticker on it says designed for XP, but another sticker says it originally came from factory with win2000. If I remember it was a single core pentium M processor 1.6ghz. If it worked, its ok for Puppy Linux or a slimmed down version of XP. But its days are numbered as everything wants more and more memory.


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## HermitJohn (May 10, 2002)

Okay, Toughbook booting now. I had reseated memory stick that I could easily get to couple times. But hadnt tried just removing it entirely and powering up. Bad memory stick. Apparently the other 256mb stick is buried under the keyboard. It was enough by itself to boot Puppy. The Asus just has the hidden stick so imagine I need to remove keyboard and replace it if I want to ever use that laptop again. Cool having the old Toughbook working though. They are pretty hard to kill short of a ball peen hammer. Most likely have to max out the memory to full 2GB to make it truly useful. Hmm, think it can go up to 2GB....


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## Nevada (Sep 9, 2004)

HermitJohn said:


> Okay, Toughbook booting now. I had reseated memory stick that I could easily get to couple times. But hadnt tried just removing it entirely and powering up. Bad memory stick. Apparently the other 256mb stick is buried under the keyboard. It was enough by itself to boot Puppy. The Asus just has the hidden stick so imagine I need to remove keyboard and replace it if I want to ever use that laptop again. Cool having the old Toughbook working though. They are pretty hard to kill short of a ball peen hammer. Most likely have to max out the memory to full 2GB to make it truly useful. Hmm, think it can go up to 2GB....


Good!


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## Harry Chickpea (Dec 19, 2008)

Remove the old laptop battery (not the CMOS battery) completely. Odds are, all it will do at this point is lug down the power from the power brick and heat up.


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## WhyNot (Jun 21, 2011)

Another idea if you don't solve the mystery: There are some laptops that will not function even on a/c power if the regular battery is either not in, will no longer hold a charge or is discharged. Typically the lights flash and nothing happens. A friend of mine had an old Asus and toward the end of its life he would have to take out the battery, unplug the a/c and hold the power button in for a minute and then put it back together and the battery would charge. This doesn't really make any sense that I know of...but he swore by it. :shrug:


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## HermitJohn (May 10, 2002)

Huh, hadnt heard before that some laptops require a good battery to be able to boot and wont just boot off AC adapter. As I mentioned the Toughbook is working. I even ordered a $4 stick of 1GB ram to replace the bad one. Will bring it up to its whopping max memory capacity of 1GB plus 256MB. The 256MB is built into the motherboard and not replaceable. The ASUS, I removed the keyboard and took out the ram stick hidden there. ASUS still wouldnt post, but pretty sure its laptop battery was dead when I got it and that it would at that time boot off the AC adapter only. I really dont need it functional with two other laptops functioning now, so not going to order extra ram stick to try and get it going. It uses close to same memory stick (200 pin) as the Toughbook so when I get that one will try it on ASUS.


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## WhyNot (Jun 21, 2011)

John-
It wasn't that the battery had to be good...just in. I had a Compaq and a Dell from the 90's that it didn't matter if the battery was dead or not, the laptops wouldn't work on A/C if the battery wasn't in.

In the early and mid 2000's I had an Acer and an Asus that did the same.

The last budget Acer I bought in 2012 was also like that. Now...there may be another cause....and maybe I just am buying laptops with defects or something. It was just a consideration to throw out there.


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